1997 Mercedes-Benz C230 Kompressor – Specifications

1997 Mercedes-Benz C230 Kompressor – Specifications

Engine: Mercedes-Benz M111 2.3-litre DOHC 16V, JE FSR forged pistons, shot-peened rods, balanced, ported/polished head, 4-inch intake, 4-inch Pipercross filter, custom intake plenum, Skunk2 68mm throttle body, custom alloy intercooler piping, Garrett GT28RS turbocharger, Trust intercooler, GReddy blow-off valve, Tial 38mm wastegate, custom exhaust manifold, custom fuel rail, Aeroquip fittings, Sard fuel pressure regulator, Siemens 550cc injectors, 3-inch mandrel-bent stainless exhaust, V-band exhaust clamps, Magnaflow mufflers, MoTeC M400 ECU, custom wiring loom

Driveline: Factory 5-speed manual gearbox, factory flywheel/clutch

Suspension: Koni adjustable shocks, Eibach Pro springs, Eibach sway bars, Nolathane bushes

Brakes: Stoptech front 332mm 2-piece rotors, 4-pot Stoptech front callipers, custom slotted rear rotors, braided lines

Wheels/Tyres: Work Meister 19×8.5-inch front rims, 19×9.5-inch rear rims, Goodyear Eagle F1 tyres

Exterior: Lumma Tuning front bumper, AMG side skirts

Interior: Factory two-tone leather interior, Defi display unit, Pioneer head unit, Rockford Fosgate P4004 amplifier, 4x Rockford Fosgate 6.5-inch Power component speakers

Performance: Dyno Power — 300hp @ wheels

ตารางคำนวนแรงม้า

แรงม้า <——————————————————–นํ้าหนักรถ รวมผู้ขับ (กิโลกรัม)——————————————————–>
750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500
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150 110 117 125 132 139 147 154 161 169 176 183 191 198 205 213 220
155 121 130 138 146 154 162 170 178 186 194 202 210 219 227 235 243
160 134 142 151 160 169 178 187 196 205 214 223 232 240 249 258 267
165 146 156 166 176 186 195 205 215 225 234 244 254 264 273 283 293
170 160 171 182 192 203 214 224 235 246 256 267 278 288 299 310 320
175 175 186 198 210 221 233 245 256 268 280 291 303 315 326 338 350
180 190 203 216 228 241 254 266 279 292 304 317 330 342 355 368 380
185 206 220 234 248 262 275 289 303 317 330 344 358 372 385 399 413
190 224 239 253 268 283 298 313 328 343 358 373 388 403 418 432 447
195 242 258 274 290 306 322 339 355 371 387 403 419 435 451 467 484
200 261 278 296 313 330 348 365 383 400 417 435 452 470 487 504 522
205 281 300 318 337 356 375 393 412 431 449 468 487 506 524 543 562
210 302 322 342 362 383 403 423 443 463 483 503 523 544 564 584 604
215 324 346 367 389 410 432 454 475 497 519 540 562 583 605 327 648
220 347 370 394 417 440 463 486 509 532 556 579 602 625 648 671 694
225 371 396 421 446 470 495 520 545 570 594 619 644 669 693 718 743
230 397 423 450 476 503 529 555 582 608 635 661 688 714 741 767 794
235 423 451 480 508 536 564 592 621 649 677 705 734 762 790 818 846
240 451 481 511 541 571 601 631 661 691 721 751 781 811 841 872 902
245 480 512 543 575 607 639 671 703 735 767 799 831 863 895 927 959
250 510 543 577 611 645 679 713 747 781 815 849 883 917 951 985 1019
เงื่อนไขความแม่นยำ 98 เปอร์เซนต์
1. กดคันเร่ง 100 เปอร์เซนต์ทุกเกียร์ตลอดระยะทาง
2. อัตราทดเฟืองท้ายลงตัวสำหรับสุดเกียร์ 4 หรือเกียร์ 5
3. สัมประสิทธิ์อากาศพลศาสตร์ประมาณ 0.35
4. ความเร็วไม่เกิน 250 กิโลเมตรต่อชั่วโมง


ข้อมูลจาก อาจารย์ ศิริบูรณ์ เนาวถิ่นสุข
MOTORSPORTS TECHNOLOGY siriboon@excite.com 0-1940-7144

The R170 SLK

The R170 SLK

 

 

The Mercedes-Benz R170 SLK arrived in January, 1997 as one of the industry’s most anticipated sports cars. That year, journalists named it North American Car of Year. The SLK was so successful that Mercedes-Benz had to double production to meet demand.

This is a thoroughly modern vehicle. The SLK’s wedge shape is a timeless design, that’s unmistakably a Mercedes-Benz. It has a folding metal roof and was introduced at a time when competing convertibles had cloth tops. To lower the top, a console-mounted button is pressed. No latches, no handles, and no wrestling with dirty canvas. Just a tap of the button and in 25 seconds, the SLK transforms from a coupe to an open air roadster.

The SLK received a facelift for the 2001 model year. Among the visual changes were new front and rear aprons, sculpted rocker panels, turn signal repeaters in side mirrors, body-color door handles, and two-color taillight glass (red/clear). All V6-powered SLK320 models received a then-new 5-spoke wheel design (7×16-inches in front, 8×16-inches in the rear), a unique air dam, metal plate door sills, power seats, telescoping steering column, wood interior trim with a combination leather/wood steering wheel and shift knob. Underneath, they received a new rear stabilizer bar, a larger fuel tank and a new trunk lid opening mechanism.

The interiors were upgraded as well. The seats were more ergonomically-designed, there was a new steering wheel, machined aluminum trim was used (in place of carbon fiber on SLK230), a Touch Shift gear indicator was added to the instrument panel, a new shift lever was used, a newly designed overhead console was added, the door panels were redesigned and had a more SL-like appearance, and a chromed hand brake button was used.

Three engines are available in the R170 SLK model line. The SLK230 has a supercharged and intercooled, 2.3-liter DOHC four. The four cylinder delivers an impressive 192 hp and 200 lbs.-ft. of torque. What’s even more remarkable is how it’s 200 lbs-ft of torque is available from 2,500 to 4,800 rpm. The second power plant is the 3.2-liter, 215 horsepower V6 of the SLK320. The standard transmission for both of these models was a close-ratio, six-speed manual. A five-speed automatic was also available.

At the top of the R170 food chain is the SLK32 AMG. This model is stuffed with a supercharged, intercooled V-6 that produces three-hundred and forty-nine horsepower. That much power in the SLK results in four point eight second zero-to-sixty sprints, and a top speed that has to be electronically limited to one hundred and fifty-five miles per hour. Backing this engine is an AMG SpeedShift equipped five-speed automatic. The SLK32 suspension has AMG specific spring rates, shock valving and stabilizer bars. This model also comes with the more powerful AMG braking package. Inside, the SLK32 is furnished with sport seats finished in two-tone Nappa leather upholstery. These seats feature integrated headrests and aggressive side bolsters. The SLK32 interior has matching two-tone leather trim on the door panels, steering wheel and gear lever. They have AMG specific instrumentation and dark bird’s eye maple wood trim.

All the equipment expected of a Mercedes-Benz is available in each of the three models; the ESP Stability Program, Tele Aid telematics, Touch Shift, heated power seats, telescoping steering column, Xenons with headlight washers, ASR traction control, Brake Assist, rain sensing wipers, etc.



Technical Data

 

Model SLK230 Kompressor SLK320 SLK32 AMG
Vehicle type Two-seat coupe/roadster with powered-operated retractable hardtop
Engine In-line four-cylinder, Roots-type intercooled supercharger 90-degree V6 90-degree V6, screw-type intercooled supercharger
Engine material 90-degree iron block/aluminum head aluminum
Valvetrain Chain-driven double overhead camshafts, four valves per cylinder, electronically controlled variable intake valve timing control Chain-driven single overhead camshaft per cylinder bank, two intake valves and one exhaust valve per cylinder
Valve arrangement 4-valves per cylinder 3-valve technology with two intake and one exhaust valve per cylinder
Displacement (cu. in./cc) 140 / 2,295 195 / 3,199
Bore (in./mm) 3.58 / 90.9 3.54 / 89.9
Stroke (in./mm) 3.48 / 88.4 3.31 / 84.0
Compression ratio 9.0:1 10.0:1 9.0:1
Horsepower @ rpm 192 / 5,500 215 @ 5,700 349 @ 6,10 0
Torque (lb-ft.) @ rpm 200 @ 2,500-4,800 221 @ 3,000-4,600 332 @ 3,000-4,600
Intake system Roots-type supercharger with intercooler Electronic throttle control, two-stage resonance intake manifold Screw-type supercharger with intercooler, electronic throttle control, two-stage resonance intake manifold
Engine management SIM 4 sequential fuel injection ME 2.8 engine control with phase-shifted twin spark ignition, two coils and spark plugs per cylinder, integrated sequential multi-point fuel injection
Max. engine speed (rpm) 6,200 6,000
Transmission Six-speed manual 
(std. on SLK230 and SLK320)
Five-speed electronically controlled automatic with driver-adaptive shift logic, Touch Shift selectable manual control (optional on SLK230 and SLK320) AMG SpeedShift five-speed electronically controlled automatic with driver-adaptive shift logic, Touch Shift manual control, actrive braking downshift, optimum gear function performance modes
Gear ratios







R2 “winter” mode
4.46:1 
2.62:1 
1.72:1 
1.25:1 
1.00:1 
0.84:1 
4.06:1 
3.95:1 
2.42:1 
1.50:1 
1.00:1 
0.83:1 

3.15:1 
1.90:1

3.59:1 
2.19:1 
1.41:1 
1.00:1 
0.83:1 

3.15:1 
1.90:1

Final drive 3.27:1 3.07:1
Stability control Electronic Stability Programming (ESP) integrating single brake application and throttle intervention for yaw control, plus ignition and throttle intervention for wheelspin control
Suspension Four-wheel independent
Front Double wishbone (upper and lower control arms), coil springs, gas-charged shocks, stabilizer bar
Rear Five-link, coil springs, gas-charged shocks, stabilizer bar, anti-lift and anti-squat geometry
Steering Recirculating ball, hydraulic power assist
Overall ratio 15.53:1
Turns, lock-to-lock 3.1
Turning circle 32.9 feet / 10.03 meters
Front Wheels 7.0×16-in.,7-spoke 
(7.5×17-in. AMG 5-spoke w/Sport Pkg.)
7.0×16-in., 5-spoke 
(7.5×17-in. AMG 5-spoke w/Sport Pkg.)
7.5×17-in., 10-spoke
Rear wheels ( 8.0×16-in., 7-spoke 
(8.5×17-in. AMG 5-spoke w/Sport Pkg.)
8.0×16-in., 5-spoke 
(8.5×17-in. AMG 5-spoke w/Sport Pkg.)
8.5×17-in., 10-spoke
Front tires 205/55R16 V 
(225/45ZR17 w/Sport Pkg.)
205/55R16 V 
(225/45ZR17 w/Sport Pkg.)
225/45ZR17
Rear tires 225/50R16 V 
(245/40ZR17 w/Sport Pkg.)
225/50R16 V 
(245/40ZR17 w/Sport Pkg.)
245/40ZR17
Brakes Hydraulic power assisted 4-wheel discs with 4-channel ABS anti-lock; Brake Assist System
Front disc diameter (in./mm; type) 11.3 / 287; vented 11.8 / 300; vented 13.0 / 332; vented
Rear disc diameter (in./mm; type) 10.9 / 278; solid 10.9 / 278; solid 11.8 / 300; vented
Front disc thickness (in./mm) 0.98 / 25 1.1 / 28 1.26 / 32
Rear disc thickness (in./mm) 0.35 / 9 0.35 / 9 0.87 / 22
Exterior dimensions (in./mm)
Wheelbase 94.5 / 2,400
Length 157.9 / 4,010
Width (without mirrors) 67.5 / 1,715
Height 50.4 / 1,279
Front track 58.6 / 1,488
Rear track 58.5 / 1,485
Curb weight 3,055 (man.), 3,110 (auto.) 3,099 (man.), 3,154 (auto.) 3,220
Aerodynamic drag (Cd) 0.35 with the top up
Interior dimensions (in./mm)
Head room 37.4 / 950
Leg room 42.7 / 1,084
Shoulder room 51.7 / 1,313
Capacities
Cabin volume (cu. ft.) 43.8
Fuel tank (gallons) 15.9
Performance
0-60 (seconds) 
manual 
automatic
6.9 
7.0
6.6 
6.6
– 
4.8
Top Speed MPH 130 – electronically limited 155 – electronically limited
Fuel economy (city/hwy) 
manual 
automatic
20/29 
23/30
18/27 
21/27
– 
18/24

TURBO CAMSHAFTS

TURBO CAMSHAFTS

Pressure Differential

Unlike a supercharger that is driven directly form the crankshaft, a turbo is driven by exhaust gas velocity. Turbochargers are an exhaust restriction (which raises the exhaust gas pressure), but since they use energy that would otherwise be wasted, they are much more efficient than a belt driven supercharger. Normally when the exhaust valve opens, there is still useable pressure in the cylinder that needs to be dumped so it will not resist the piston trying to go back up the bore. That pressure makes high exhaust gas velocity. With a turbocharged engine, this is the energy that is used to spin the turbine.

With a well matched turbo / engine combo, boost pressure should be higher than exhaust gas pressure at the low side of the power band (near peak torque). As the engine nears peak hp, the pressure differential will get nearer 1:1. At some point the pressures in the intake and exhaust will be equal then crossover making the exhaust a higher pressure than the intake. At peak hp there will usually be more exhaust gas pressure than boost pressure. The ultimate goal is to have as little exhaust backpressure possible for the desired boost.

If the turbocharger is matched well to the engine combination, the camshaft selection will not need to be much different than that of a supercharged engine. The problem is that most factory turbo engines have turbo’s that are sized too small and will usually have more back pressure than boost pressure over much of the useable power band. Car manufactures do this in an attempt to reduce turbo lag. When a turbocharger is too small, it will be a bigger restriction in the exhaust, causing more back pressure. A big mistake of turbo owners is to crank the boost up as high as they can thinking they are going faster, but in reality, chances are that they are just killing the efficiency of the turbo and most gains are lost. If you want to run higher boost levels and back pressure is a problem, cam timing can be altered to give respectable power increases for much cheaper than a new turbocharger. Before you go increasing boost and changing cams, remember that the oxygen content into the engine will increase power, not boost pressure. A good flowing head with a good intercooler can make a lot of power without high boost. You may not need more boost to get the power you want.

Valve Overlap

If you’re one of many factory turbo car owners with a turbo sized too small, there will be higher exhaust pressure than intake.  You should see that if both valves are open at the same time, the flow would reverse. Any valve overlap is a no-no if you’re looking for higher boost with a restrictive turbine housing. The exhaust valve will usually close very close to TDC, but there is will still be more pressure on the cylinder than in the intake. You must allow the piston to travel down the bore until the pressure is equalized. If the cylinder pressure is lower than the intake manifold pressure, no reverse flow will take place. This means that the intake valve needs to open 20-35° ATDC, depending on the amount of boost you’re using. Most street turbo’s will work well when the valve opens close to 20° ATDC, only when boost gets near 30 psi will you need to delay it as much as 35° ATDC. In low boost applications (under 15 psi or so), opening the valve closer to TDC and maybe keeping the exhaust valve open a little after TDC is a compromise for better throttle response before the boost comes on. As you increase boost, you will need to delay the opening of the intake valve to avoid reversion. You want the intake valve to open as soon as possible, in an ideal situation, the intake valve should open when the pressure in the cylinder is equal to boost pressure. This can cause a little confusion with cam overlap. If the exhaust valve closes before the intake opens, the overlap will be considered negative. If the exhaust valve closed at TDC and the intake opened at 20° ATDC there would be -20° of overlap. In this type situation, pumping losses are quite large, although the turbo will still use less power than a crank driven supercharger.

If you have a well matched turbo for the engine and application, it is a different deal altogether. A well matched turbine housing on the turbo will usually work well with cams with a lobe separation in the 112-114° area. If there is more pressure in the intake than in the exhaust, a camshaft suited for superchargers or nitrous will usually works well. When the exhaust backpressure is lower than the intake, reversion is not a problem, actually just the opposite is a problem. More pressure in the intake can blow fresh intake charge right out the exhaust valve. This can be a serious problem with a turbo motor since the charge will burn in the exhaust raising temperatures of the exhaust valves and turbo. This is also a problem with superchargers, which is why supercharger cam profiles usually work well with turbo’s. In this type situation, the power required to turn the turbine is nearly 100% recovered energy that would have normally been dumped out the tailpipe, basically free power. Many will argue that nothing is free and you need pressure to spin the turbine and this must make pumping losses. They are wrong because a turbo is not getting anything for free at all, it is just making the engine more efficient. It is true that there are pumping losses, but on the other hand there are pumping gains as well. If the exhaust back pressure is lower than the intake, the intake pressure makes more force on the intake stroke to help push the piston down. At the same time another piston is on it’s exhaust stroke. So the intake pressure is more than canceling out the exhaust pressure. Not free, just more efficient.

Valve Lift

By delaying the opening of the intake, the duration of the cam will be much shorter. A short duration intake works well with a turbo, but the problem is that sufficient lift is hard to get from such a short duration. This is where high ratio rockers can really pay off. A cam for a turbo engine can delay the intake opening by over 40° compared to an cam for a normally aspirated engine. This makes for much less valve lift when the piston is at peak velocity (somewhere near 75° ATDC), any help to get the valve open faster will make large improvements.

Roller Camshafts

Turbo motors place a large flow demand at low valve lifts, and roller cams cannot accelerate the valve opening as fast as a flat tappet. They do catch up and pass a flat tappet after about 20° or so, but up until that point the favor goes toward the flat tappet cam. The area where rollers really help in turbo motors (and supercharged) is cutting frictional losses. Any forced induction engine will need more spring force on the intakes. If you run a lot of boost, you’ll need quite a bit more spring force to control the valves. As spring forces gets higher, the life of the cam gets reduced. A roller tappet can withstand more than twice the spring pressure as a flat tappet with no problems. On the exhaust side, it’s not the springs that put the loads on the cam lobes. The problem there is that there is still so much cylinder pressure trying to hold that valve closed. This puts tremendous pressure on the exhaust lobes. So when high boost levels are used, consider a roller cam. I would definitely consider a roller cam on engines making more than 20 lbs. of boost.

 

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Frequently Asked Questions form turbo

  • With the turbo located in the rear of the vehicle, is there turbo lag?
    No, due to extensive engineering and proper sizing of the turbos and piping, the turbochargers operate very well at this remote location. All of our systems will produce full boost below 3000 rpm. If you were to take a front-mount turbo system and place it at the rear, you would have lag issues, and similarly, our turbo system wouldn’t work properly if front-mounted. Also, our intake tubing volume is about the same as most conventional turbo setups that are running a front-mounted intercooler, and is less than many of them that run large intercoolers. Our system is not like a small compressor filling up a large air tank, it is like a huge compressor filling up a very small volume. Our systems compress the intake tubing in about .05 seconds. If our patented and innovative rear-mounted technolgy had problems with turbo lag, we would not have the large number of happy customers that we have today. Please visit our Testimonials page for more insight.
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  • Does water get into your engine due to the filter location?
    No, every kit includes either a snorkel kit (which locates the air filter high in the rear quarter panel) or an air filter shield. We also include an Outerwears Dry Charger which is proven to protect the filter under very dusty or wet conditions. 
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  • Without a muffler, how does the vehicle sound?
    The turbo does an amazing job of muffling sound. Most people think it sounds like a performance muffler. You can still add a high flow muffler to the system, but most of our customers like the performance sound with just the turbo.
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  • How long does it take to install your system?
    Average install times are about 12 hours for first timers. Our install techs usually spend about 8 hours on a typical install.
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  • How is the turbo lubricated?
    Our system uses the engine’s pressurized oiling system to supply the turbocharger. This pressurized oil travels approximately 12 feet through tubing which dissipates heat out of the oil just like an oil cooler to provide cool oil to the turbocharger. The oil is then scavenged from the turbocharger via an electric oil pump which returns the oil to the engines valve cover through another long length of tubing which again cools down the turbo-heated oil before entering the engine.
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  • Does installing a STS turbo system void my vehicle’s warranty?
    No, it is illegal for a dealership to void your warranty simply because you have modified your vehicle. It is the dealership’s responsibility to prove that a modification was the reason for a failure. With that said, some dealerships are more performance oriented and are more willing to work with customers. We suggest consulting with your local dealership regarding their warranty specifics. For additional questions, see the Magnuson Moss Warranty at http://www.enjoythedrive.com/content/?id=8124 
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  • How much boost can I run with this turbocharger?
    The basic kits run 5-6 psi boost. The turbocharger on our basic kits is capable of producing higher boost of 15+ psi. However, in most cases a larger turbocharger would be more efficient at higher boost levels. There is more to running higher boost than just turning the boost up. You must also be able to meet the fuel demands of higher boost as well as set up the engine to handle the extra power so that you don’t cause mechanical failures with the engine.

    Higher boost will also raise the “boosted” compression ratio of the engine that will require higher octane fuel to prevent detonation. Bottom line – Don’t crank up the boost unless you have done your homework and made the necessary modifications to handle the boost.

    We handle high boost applications on an individual basis to ensure that you are getting the right turbocharger setup for your specific needs.
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  • What happens if something goes wrong with the oil pump?
    In the event of an oil pump failure, the system is equipped with an alarm which will sound inside the vehicle to warn you that you are experiencing an oil system problem so that you can prevent any damage to the turbo or engine. This alarm is designed to warn you of any problems with the oil pump well before a complete shutdown of the pump.
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  • If water hits the hot turbo, will it crack?
    Seems like it might when you first think about it, however, when I asked the Garrett engineers this questions they just laughed. There is a big difference in water splashing on a hot turbo and submerging it in enough water and fast enough to really cool it down fast. Both the new turbocharged Vette systems and the new Porsche systems sit the turbo down low and exposed to water and anything else that goes under a car.

    Plus, our turbos just don’t get that hot and when weather conditions are such that there is a lot of water around, you can’t push enough boost to get the turbo hot anyway because you’d just spin the tires.
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  • What type of tuning is needed with this setup?
    We recommend tuning with any forced induction. There are a variety of options available from custom dyno tuning, to mail order tunes to FMUs. STS Turbo offers tuning packages with almost all bolt-on turbo systems. These complete systems come with fuel system upgrade components and an appropriate tuning device with STS Base Tune included. Most tuning solutions offer user adjustments so that the base tune can be dialed in for each individual vehicle and conditions. Custom dyno tuning is also available at selected STS Turbo Distributors. For more information see Tuning on the Products page. For high boost and custom applications, upgrade tuning solutions and fuel system upgrades are available through STS Turbo or through STS Turbo distributors.
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  • Is a turbo timer or pre-lube device necessary with your system?
    No, the turbocharger temperatures on our systems are approximately 500F cooler than turbo temps on conventional systems so the oil doesn’t get hot enough to carbonize in the turbocharger bearings. With the turbocharger located where it is exposed to ambient air rather than trapped under the hood, the turbocharger quickly cools down as well so cool down times after runs don’t need to be 5 to 10 minutes. As far as pre-lubrication, our system incorporates our “Wet Start” system which keeps oil at the turbo inlet at all times so that the turbocharger has an instant oil supply at start up.
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  • Do I need to put headers on to optimize the turbo system?
    No, the extra expense and work to install aftermarket headers isn’t necessary. Headers are designed to eliminate backpressure in the exhaust system and facilitate exhaust scavenging and flow on normally aspirated engines. Turbocharged engines work on slightly different principles. Namely, there is exhaust “Pressure” between the cylinder heads and the turbocharger because the turbocharger is the smallest diameter orifice in the exhaust system. The turbine housing gets smaller in diameter to increase the velocity of the exhaust gasses before they hit the turbine wheel. This is how you get 100,000 rpm wheel speeds.

    Turbocharged exhaust gas pressures can see as high as 30+ psi on high boost applications. So spending money on higher flowing exhaust components designed to lower exhaust backpressure is usually a waste of money. This money would be better spent on an upgraded turbocharger which would produce more efficient boost with less backpressure or just spending the money on upgrading the engine and fuel system to handle more boost.
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  • Doesn’t heat create the velocity in the exhaust gasses to spool the turbo?
    No, heat doesn’t create velocity. Heat creates volume. If you look at any of the physics laws for gasses, you will find that pressure and volume and heat are related. PV=NRT is a popular one, The V isn’t for velocity, it is for Volume.

    The turbine housing is what creates the velocity. The scrolling design that reduces the volume of the exhaust chamber as it scrolls around causes the gasses to have to increase in velocity and pressure to maintain the same flow rate.

    Hotter gasses have more volume, thus requiring a higher A/R which in effect means that it starts at say 3″ and scrolls down to approximately 1″. Lower temperature gasses are denser and have less volume, so they require a lower A/R housing which would start at the same 3″ volume, as the turbine housings use standard flanges, and scroll down to say 3/4″.

    Now if you were to reverse the housings in application, the conventional turbo would spool up extremely quick, at say around 1500 rpm but would cause too much backpressure at higher rpms because the higher volume of gas couldn’t squeeze through the 3/4″ hole without requiring a lot of pressure to force it through. On the reverse side, the remote mounted turbo with its cooler denser gasses, wouldn’t spool up till say around 4000 rpms but once spooled up would make efficient power because it doesn’t require hardly any backpressure to push the lower volume of gas through the larger 1″ hole.
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  • How efficient is the intercooling from your tubing?
    At 5 to 6 psi we typically get at least 50% intercooler efficiency numbers from our systems and some of the truck systems which have better exposure to cold air are even better. Combine this with a pressure drop of only about 1/4 to 3/4 psi and it makes for very good numbers.

    Testing on our LS1 produced the following results:

    Turbo outlet temps at 5 psi boost were 175F and intake temps were 115F which is about 52% efficient.

    Turbo outlet temps at 8 psi boost were 225F. This is a 50F increase with only 3 psi added to turbocharger boost.

    For those wanting to run more boost we recommend a front mounted intercooler. We sell bolt-on solutions for the Hemi and the GTO. We will be coming out with more applications soon.
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  • Isn’t there a huge pressure drop with such long intake tubes?
    No, if the pipes were 100′ long there would be but we are only talking a few extra feet and we size the charge air tubing so that it will flow without a large pressure drop. We typically will get about 1/4 to 3/4 lb difference between the turbo compressor and the intake manifold, which is nothing compared to the pressure drop across an intercooler. With high boost applications, these numbers will increase slightly.
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  • Don’t turbos have to be really hot to work properly?
    Putting a torch to your turbo and getting it hot doesn’t produce boost. What produces boost is airflow across the turbine which causes the turbine to spin. If turbochargers required very high temperatures to produce boost, Diesel trucks and Methanol Race cars wouldn’t be able to run turbos. However, each of these “Low Exhaust Temperature” vehicles work very well with turbochargers when, like any turbo application, the turbocharger is sized correctly.

    In a conventional, exhaust manifold mounted turbocharger system, the extra heat causes the air molecules to separate and the gas becomes “thinner” because of the extra space between the molecules. This extra space increases the volume of air but doesn’t increase the mass of the air. Because the volume is higher, the velocity of the gas has to be higher to get it out in the same amount of time.

    By mounting the turbo further downstream, the gasses do lose heat energy and velocity, however, there is just as much mass (the amount of air) coming out of the tailpipe as there is coming out of the heads. So you are driving the turbine with a “denser” gas charge. The same number of molecules per second are striking the turbine and flowing across the turbine at 1200F as there is at 1700F.

    Front mounted turbos typically run an A/R ratio turbine housing about 2 sizes larger because the velocity is already in the gasses and the volume is so big that the turbine housing must be larger to not cause a major restriction in the exhaust system which would cause more backpressure. With the remote mounted turbo, the gasses have condensed and the volume is less, so a smaller A/R ratio turbine housing can be used which increases the velocity of the gasses while not causing any extra backpressure because the gas volume is smaller and denser.

    Sizing is everything with turbos. There is more to sizing a turbo for an application than cubic inches, Volumetric Efficiency, and RPM ranges. A turbo must also be sized for the exhaust temperatures. A turbine housing sized for 1700F gasses would have lag if the gasses were 1200F. This is why turbo cars have lag when they are cold and not warmed up yet. Both systems work well if sized correctly.
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  • How much octane do I need to run a turbocharger?
    We recommend running Premium gasoline on vehicles that are running 5 to 12 psi.
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  • What about ground clearance with the turbo down low on Camaro?
    Ground clearance hasn’t been a problem as all of the kit sits higher than the stock equipment. The lowest areas are near the wheels which give it added clearance going over bumps. 
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  • What is the difference between a Supercharger and a Turbocharger?
    First of all, there are a couple different types of superchargers (positive displacement and centrifugal). The most popular these days seems to be the centrifugal supercharger which is basically the same design compressor as a turbocharger compressor. These compressors both increase in airflow and efficiency with impeller RPM’s. (Which basically means that doubling the impeller RPM doesn’t double the airflow, it increases the air flow exponentially.) So in the case of the supercharger, where it is directly run from a belt and pulley attached to the crankshaft which ties impeller RPM in a direct ratio to crankshaft RPM, the boost increases linearly with engine RPM.

    Example: If you want to run maximum boost of 8 psi, you would gear the drive pulleys to produce 8 psi at maximum engine RPM. Lower RPM’s would produce less boost linearly. I.E. 8 psi @ 6000rpm, 5 psi @ 4500rpm, 3 psi @ 3000rpm, and 2 psi @ 2500rpm.) Thus, maximum boost is only attained at maximum engine RPM which only lasts for a fraction of a second then when the engine shifts to the next gear and the RPM’s drop back down, so does the boost which then builds up again with increasing engine RPM’s.

    Supercharged engines produce good “maximum rpm” dyno numbers. Don’t be fooled by maximum dyno numbers. Unless you have a “Snowmobile Clutch” in your vehicle which allows your engine to stay at peak RPM all the way down the track, what you need is “Usable Power” which comes from sustained boost levels across the entire RPM range. This is where the Turbocharger outperforms the Supercharger.

    By using exhaust gasses to drive the turbocharger you gain two benefits: First is that you don’t pull Horsepower off of your crankshaft to drive the compressor (Just like you wouldn’t replace your electric fan with a large “belt driven” fan or run your A/C down the track because these devices take Horsepower to run as does a Supercharger compressor capable of pumping 50 pounds of air per minute @ 8 psi). Secondly, since the turbocharger is driven by exhaust gasses, the more air the turbocharger puts into the engine, the more exhaust gasses the engine produces, which in turn produces more turbocharger RPM’s and air discharge or “Boost”. So, to sum it all up, the turbocharger can go from literally “No Boost” to “Full Boost” in a fraction of a second because of the compounding effects of the Compressor Efficiency increasing with impeller RPM’s and the compounding effects of the Exhaust Gas increasing exponentially with increasing Boost.

    So if you are only concerned with Peak Dyno Numbers the supercharger does produce good “Peak” numbers, but if you want “Full Boost” across a broader RPM range along with those high “Peak” Dyno numbers. The Turbocharger is a better solution.
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  • Is their any way I could upgrade once I build a shortblock to handle more boost or will I have to buy an entire kit again?
    That is the beauty of the turbocharger. If the engine is built to handle it, power can be gained by simply turning up the boost. The turbo kit does not need to be upgraded. However, there are several turbocharger upgrade options which will be more efficient at higher boost levels. The stock turbo is capable of 15 psi boost with some loss in efficiency. We recommend putting on the turbo that best suits your end result goals from the start of your project. This will remove the need for a turbo upgrade later. Then when you are ready for higher boost, just flip the switch on our dual stage boost controller to “HI” and your upgrade is that easy.
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  • If I want to run higher boost will I need a bigger wastegate?
    Running higher boost doesn’t require a larger wastegate, in fact in most situations running lower boost requires a larger wastegate than high boost applications. The wastegate flows exhaust out to lower the boost level. The lower the boost requirements, the more exhaust has to flow through the wastegate valve. Running higher boost will require a stiffer wastegate spring or the use of a boost controller. Our Electronic Dual Stage Boost Controller works very well and gives you the option of Hi or Low boost at the flip of a switch.
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  • How does your dual stage boost controller work?
    The electronic dual stage boost controller lets your wastegate operate normally on the “low” setting on the switch. When you flip the switch to “high” the system adds pressure to the other side of the wastegate diaphragm. You can choose how much pressure is added, 0-5 psi or 0-15 psi. The “high” setting is adjustable and once set at your predetermined amount, will give you that much more boost above the “low” setting. If your wastegate is 5 psi, you’ll run 5 psi on the low setting. If you set your controller to 3 psi, when you flip the switch to “high” you will have 8 psi boost.

    This system can also be used to “arm” the methanol injection or water injection system so that it only runs on “high” when you need it and doesn’t run out of fluid driving around town. System can also be set up so that when the methanol system isn’t working (if it runs out of fluid) the boost can be defaulted back to “low” boost as to not damage the engine. 
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  • Will a bigger cam make more power with a turbo?
    Cam choice in turbo applications is critical. In many cases, a stock cam will work better than a typical “race cam” that would work well with an aspirated engine. What you want to avoid is the “intake and exhaust valve overlap”. This is the time that the exhaust and intake valves are open at the same time. In aspirated engines, this theory facilitates the scavenging of all burnt exhaust gasses from the cylinder after the power stroke so that an “uncontaminated” and 100% burnable charge fills the cylinder on the next cycle which produces maximum power. Some of this condition can be tolerated with supercharged applications as it merely blows some of the boost out with the exhaust. However, on turbocharged applications (many people believe that the boost also is just blown out with the exhaust) however, the opposite is truer to the case. With exhaust pressures sometimes exceeding boost pressures, the exhaust can flow into the cylinder and into the intake manifold during this overlap time which contaminates the intake charge, decreases HP, and can cause pre-ignition as well. Also, most cam applications begin flow at .050″ of valve lift. On forced induction systems, there can be substantial flow below this amount of lift because of the higher pressures behind the valves.

    So, if in doubt go smaller on your cam rather than larger. Go wider on lobe separation angles (114 degrees is usually safe) Smaller on durations (stick around 220) and check with the cam manufacturer to make sure that it is a good “turbo” cam and not just a generic supercharger/turbo cam. A good option is to install a set of higher ratio roller rockers on your stock cam. Better pushrods and stiffer valve springs will help as well because boost and cylinder pressures will be way higher than stock. Stiffer springs will help close the valves against the pressure of incoming air and stronger pushrods will help open the exhaust valve against the increased cylinder pressures.
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  • What type of coating is on the pipes?
    All of the intake pipes are HPC coated. HPC coating is the leader in thermal coatings. They look great and they don’t rust. For more information visit – http://www.hpcoatings.com/
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  • Aren’t the stock manifolds and exhaust system restrictive?
    For certain normally aspirated or supercharged systems, stock exhaust is somewhat restrictive and can cause backpressure in the system and rob HP. However, with turbocharged applications, the turbocharger is the biggest restriction in the exhaust system. All of the exhaust gasses (except the ones that are vented out the wastegate) pass through the turbine housing. The inlet hole in the turbine housing is about 2″x3″, however, as it scrolls around the housing it gets smaller and smaller causing the exhaust gasses to increase in velocity. At the smallest point where the gasses exit and hit the turbine wheel, the hole is no bigger than about 1″ in diameter. This tiny hole will create backpressure in the entire exhaust system prior to the turbo and clear back to the exhaust valves.

    So sticking larger diameter pipes and high flowing headers doesn’t make lots of sense when you have a 1″ tailpipe hole. These additions probably won’t hurt, but the money would be far better spent elsewhere. Our Turbo Camaro put down 522 RWHP and 620 RWTQ through the same restrictive exhaust manifolds and I-pipe that came stock on the car. Turbocharging is very different than Supercharging or Normally aspirated. That is good news because you don’t have to spend the extra money on the exhaust system!
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  • Will your methanol injection setup work with any turbocharged car?
    Yes, our Methanol System is designed to work with any turbocharged, supercharged, or even Normally Aspirated engines. We typically will see 100F intake temperature drops with this system. The Octane requirements are lowered, the cylinder temperatures are lowered, and the exhaust temperatures are lowered. It’s all good! We installed our Methanol System on a Supercharged Viper. We lowered his intake temperatures from 220F down to 100F. The extra fuel allowed him to lean out his injector map and the water cooled the cylinder temps down enough to add 4 degrees of ignition timing. He lowered his ET from a 10.8 down to a 10.6. He raised his MPH from 134 to 140 MPH!
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  • How does your methanol system work?
    Unlike many methanol or water injection systems on the market. Ours doesn’t just turn on at a predetermined boost level and dump fluid in, causing flooding at lower rpms and part throttle positions and leaning out at high rpms and WOT.

    With our Sequential Methanol System, you inject your extra fuel and/or water mixture at the same rate as your stock fuel injectors do. The more throttle you give it, the more fluid goes in. The higher the rpms go, the more fluid goes in. The system is adjustable as to when it kicks on, and also adjustable as to the gallons/minute flow rate, as well as tunable with the Methanol/Water ratio. It is simple to install and easy to adjust and tune for optimum performance. Combine this with our Electronic Dual Stage Boost Controller and set it up to only run on High Boost. You can also set it up so that if the Injection shuts off for any reason, such as it runs out of fluid, the boost controller will default back to low boost. It is a definite “Must Have” for any turbocharged or supercharged vehicle.
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  • How much cooling is provided by the Methanol system?
    The amount of intercooling provided by the Methanol Injection System is somewhat varied by how much methanol you are injecting. Here are results of testing we did on the LS1 Camaro:

    At 5 psi without methanol, the turbo outlet temps were 175F and intake temps were 115F which is about 50% efficient.

    At 8 psi with the Methanol Injection System running, turbo outlet temps were 225F and intake temps were 70F. This is 94% intercooling efficiency. All this without the cost and installation problems that go along with trying to put a large intercooler into the front of your vehicle.
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  • Where do you mount the Methanol Injection tank?
    The tank can mount just about anywhere. We usually stick it in the rear and mount the pump there also just for better weight transfer. FWD’s would probably want it up front though. You don’t want it to be exposed to a lot of heat though as the Methanol boils at about 150F. We also have several tank sizes to better accommodate individual needs.
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  • What intake air temps do you get?
    IATs on vehicles with our intercoolers run about 10-20 degrees above ambient under boost. If you are running 5 psi without an intercooler you should see IATs 50 to 70 degrees above ambient under boost.
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  • Will this system work with my modified stroker and high stall converter?
    Yes, the system will work with different engine sizes and converter options. However, we handle these modified cars on an individual basis so that the proper size of turbocharger can be installed with the kit. We have several turbocharger options that we can tailor to suit individual needs without adding extra costs to the kit. We also offer upgraded turbochargers for those who want to get maximum efficiency and HP.
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Supercharger tuning through cam selection and cam timing

Supercharger tuning through cam selection and cam timing

April 27, 2009

By 

Camshaft tuning is an essencial part of supercharger tuning. Camshafts orchestrate the valve opening and closing events in the engine and decide whether what comes out of our motor is beautiful high power music, or a mess of dysphonics.

The use of the proper supercharger optimized cam shaft can go a long way towards supercharger tuning and give considerable power gains for the money invested.

 

To understand camshaft timing and camshaft selection we have to understand first:

 

Relativity:

 

Changing when the valves open or close (intake or exhaust) changes the the valve timing with respect to:

  • The piston position inside the cylinder. Depending on where the pistons is in the stroke, and where we are in the combustion cycle, then opening the valves will exploit the pressure difference between the cylinder and the intake and exhaust manifolds.For example it would make sense that the ideal time to open the intake valve is when there is peak vacuum inside the cylinder so that when the valve opens, the maximum amount of fresh air can be ingested. Similarly, it makes sense not to open the exhaust valve until peak cylinder pressures have been achieved inside the combustion chamber and the combustion is complete and all the power is extracted.
  •  

  • The high and low pressure pulses created by the design and runner lengths of the intake and exhaust manifolds.It would make sense to open the intake valve just as the reflected pressure waves in the intakemanifold reach the intake valve as a high pressure portion of the wave, thus opening the valve at this high pressure point gives a ‘ram air’ effect through volumetric effeciency resonance tuning increasing air ingestion which increases power.Similarly on the exhaust side, it makes sense to open the exhaust valve, just as the reflected low pressure (vacuum) portion of the exhaust wave (reflected back from the collector) reaches the back of the exhuast valve. At this point in time there is both peak pressure inside the cylinder, and vacuum in the exhaust which creates a higher pressure differencial and a faster evacuating exhaust gas.
  •  

  • With respect to the ignition timing event, for example a shorter duration or advanced exhaust cam, opens the exhaust valve sooner with respect to when the mixture was originally ignited, this means that although by advancing the exhaust cam we may have matched our header design and opened the valve with the lowest possible exhaust back pressure for best effeciency, at the same time, we have reduced the amount of time that the mixture is combusted and possibly opened the valve before reaching our peak cylinder pressures and thrown away some horsepower.
  •  

  • The intake valves with respect to the exhaust valves: and this is usually described in terms of lobe seperation angles (the offset in degrees between the center of the exhaust cam and between the center of the intake cam), or in terms of how many degrees of overlap (the number of degrees that both intake and exhaust valves are open at the same time).

Since the combustion inside the cylinder occurs at a much higher pressure than atmospheric pressure, and since exhaust valves are usually smaller than intake valves (for this same high pressure reason) then exhaust gas velocity is much higher than intake gas velocity. So, in some engines it is beneficial to open the intake valve earlier than usual during the last part of the exhaust stroke, this is called overlap. During overlap – at the very end of the exhaust stroke – the amount of pressure left in the cylinder is low so it is possible to breathe in new air under atmospheric pressure, at the same time, the high velocity of the exhaust gasses exiting help draw in even more fresh air from the intake side in an effect much like ‘syphoning’ where the fluid (in our case air) flows as a continuous stream drawing in new intake air after the old exhaust gas leaves.

The other part of phenomenon that relates to timing intake vavles with respect to exhaust valves is the duration of time where both valves are absolutely closed, which is your power stroke. This is the part of the combustion cycle where the mixture can be compressed and combusted. If either (or both) intake or exhaust valves are open you will not be able to neither compress nor combust the mixture, and the absolute duration of time (in degrees of rotation) that your mixture is combusted and allowed to reach peak cylinder pressures is affected by camshaft selection and cam timing. One thing to note is that the valve angle has alot to do with exhaust scavanging, obviously you will get maximum scavanging if the exhaust and intake valves had ‘line of sight’ i.e. if the valves were seperated  by an angle of 180*. If so, the exhaust air can directly pull in new air. Conversely, you would have the least possible scavanging if you had valves that were at a narrow angle (zero degrees at the extreme) between each other, so that the air would essencially have to make a U turn to come in through the intake and get pulled out the exhaust.

So different motors respond differently to overlap depending on the exhaust back pressure and the valve angle.

 

Duration:

Cam duration is the number of degrees of the entire 360* rotation that the intake or exhaust valve is open. The longer the duration, the more air you can get into the motor, the more overlap you have (which helps more with higher rpm power performance), the shorter your power stroke is (which reduces your combustion duration and your peak cylinder pressures reducing low rpm fuel effeciencly and clean idle….etc

Increased duration (with it’s increased overlap and scavanging) also gives the opportunity for exhaust gasses to get to the intake, or intake gasses to leak to the exhaust, and so are more sensitive to proper timing events otherwise we can get some negative effects from being ‘overcammed’

Lift:

Lift is how far or how deep the valve opens into the cylinder. The more lift you have, the less the valve is a restriction to incoming air because it is farther away from the direct path of entering or exiting air. Adding lift in general adds power to all rpms, depending on how well the camshaft (and valve train) can accelerate the valve to a higher lift number in a short duration. It’s like a ramp, the shorter the duration and higher the lift, the steeper the ramp. So what happens here is that if your valve train isn’t light enough and well controlled (Through proper valve springs or hydraulic lifting and damping) to operate that rapidly then lift will give you improved performance at lower rpms (where there is alot of time to move the valve to peak lift) but reduced performance at higher rpms, where there are more rounds per minute and so less time per round, and thus less time to go up the steep ramp and push the valve out to full extension.

Lift is good, but usually people don’t try to radically increase lift on their aftermarket cams because of a few considerations:

  1. Make sure that at this new lift, that there is still enough clearance between the valve (at full extension) and the cylinder (at top dead center) to prevent any catastrophic mechanical failure.
  2. Upgrade to lighter valve train, with stiffer springs or dual valve springs to have more control over the valve with this steeper cam profile.
  3. It does add power but it doesn’t shift the power curve up or down as radically as chaning cam duration does, and so in most aftermarket applications we really want a cam to give us peak power at a certain rpm range and so we care much more about the best duration (and some added lift).

 

I know this is a somewhat complex topic, but I need to make sure we’re speaking the same language before we go into how this relates to superchargers. Before you decide which camshaft to use (or how to adjust the timing on your stock cams) you have to look at one very important thing:

 

Your exhaust system and exhaust back pressure:

If you have a stock log type exhaust manifold, with a close coupled cat, with a dual cat exhaust system, small exhaust tubing, and a couple of restrictive mufflers on your car then it is possible at peak power to have upto 10psi of back pressure.

If this is the case, my first recommendation would be to upgrade to a high flow, low pressure exhaust system because of the potential power gains; however, I do know that some of our readers have cars that they are setting up for their parents or for dual use where their partner or the laws in their location …etc are really strict when it comes to any added exhaust noise or any aftermarket exhaust. In this case, where exhaust upgrades are not an option, then you must select your camshafts, and tune your cam timing to where you have ABSOLUTLEY the minimum possible amount of overlap. If you have significant overlap, then the more you rise above about 4500 rpms the more your supercharger will suffer and the more power you will waste. If the supercharger is geared to 7psi of boost for example, then during overlap, the cylinder sees 7psi of boost on the intake side, and 10psi of back pressure on the exhaust side, the net result is that air will flow from the high pressure zone (the exhaust) to the lower pressure zone (the intake) and so your cylinder will start to fill with exhaust gases. As the rotation continues, the exhaust valve will close and overlap will end, and the intake valve will stay open for the remainder of the intake stroke (for the rest of the duration of your intake cam), and the rest of the cylinder will fill with fresh air.

What happens here is that we get a cylinder that filled for 30* of overlap with exhaust air, and then filled for another 210* (of the original 240* of duration for a typical street cam) with fresh air. The result is a cylinder that is only 85% filled with fresh air or an engine that is literally 15% smaller in displacement! On the other hand, if our supercharger is geared for 18psi for example, then during overlap we will have 18psi on the intake side and our exhaust back pressure of 10psi on the exhaust side, the net result of this overlap is that our supercharger is effectively only producing 8psi worth of differencial pressure between the intake and the cylinder and so we are only going to get a power boost of 8psi during overlap. So, during those 30* of overlap the supercharger is only effectively porducing 8psi of boost, and after that once the exhaust valve closes, the supercharger will be able to go back to operating at full boost for the other 210*. The net result is something like 16psi of boost so 2psi (or about 12%) of our power was wasted.

 

Illustration of the 4 strokes , cam duration, and cam timing

Illustration of the 4 strokes , cam duration, and cam timing

 

 

 

 

Supercharger tuning through cam selection and cam timing

Intake cam:

Because of the negative effects of overlap on a supercharger car’s performance, and especially in the case of high exhaust back pressure as is the case with most factory supercharged cars, we find that the optimal cam duration for the intake cam is typically 30-40* of duration less than a normally aspirated camshaft for the same peak power RPM. The decision to reduce the intake cam duration rather than split the duration reduction between the intake and exhaust cams, is that the intake cam will flow air under pressurized conditions (due to the addition of the supercharger and the increase in intake manifold pressure) and so at a reduced intake cam duration the engine will still be able to get it’s full share of intake air. At the same time, the high rpm effeciency improvement from the reduction of overlap will also boost power production with a more conservative cam. Finally, if we would like to get more flow from the intake cam, there is still the option of using a higher lift camshaft (with a steeper profile due to the decreased duration) with supporting valvetrain modifications to make sure valve float doesn’t occur at higher rpms.

 

Intake cam timing:

The cam timing for the intake cam would ideally be retarded which would move the intake cam opening event farther away from the exhaust valve closing event so as to reduce or eliminate overlap, and as a side effect the power stroke duration will increase by retarding the intake cam which can also compensate for the lost power from the duration reduction.

 

Exhaust cam:

The exhaust cam duration and lift for a supercharged version of the motor should be similar to a nitrous camshaft, in the sense that the exhaust cams on nitrous specific builds have:

1- Very healthy cam duration & very healthy cam lift to allow a severely elevated amount of exhaust gases to be able to effeciently exit the motor when the nitrous is activated and the horsepower (and thus the exhaust gasses) have both doubled in quantity.

2- As little or no overlap if possible, as any overlap would mean that nitrous would be sprayed from the intake side and out the exhaust, which is wasteful of our limited supply of nitrous. Similarly the more overlap we have, the harder the supercharger will have to work because of what we explained earlier about either exhaust reversion into the intake, or the supercharger pressurizing the exhaust.

 

Exhaust cam timing:

Advancing the exhaust cam both opens and closes the exhaust valves sooner. Opening the exhaust valve sooner slightly reduces the power stroke, but at the same time it reduces overlap and makes better use of our supercharger. Typically an an advanced exhaust cam combined with retarded intake cam will provide the best results on a supercharged car, especially with a restrictive exhaust.

If we had a high flow exhaust system installed, then it may not be beneficial to advance the exhaust cam, a high flow exaust system that is optimized for our engine’s power requirements can clear the combustion chamber of all it’s gasses very effeciently. Having a high duration exhaust cam, a low back pressure exhaust system and a no overlap what so ever camshaft means that we are giving the exhaust gas plenty of time to exit they cylinder, the intake valve still hasn’t opened (because the we have decide to retard it, or use a conservative cam with less duration) and so the supercharger is not pushing any new fresh air in yet, now the cylinder is void and so some of the exhaust gas can revert back into the cylinder, then the exhaust valve will close, and then the intake valve will open only to find the cylinder already partially filled with exhaust gases.

This isn’t a problem with a restrictive exhaust because a restrictive exhaust will take some time to clear the cylinder at a lower velocity, however with a higher flow exhaust system we must be careful not to dial out ALL of the overlap in the cam timing, or to overcam the exhaust cam (using too much duration).

So exhaust cam timing can be advanced or retarded, depending on the exhaust modifications and the intake cam selection and thus must be dynotuned.

 

It’s important to note that with all of these changes in cam selection , overlap, power stroke duration, and cam timing, that the power stroke duration is effected and if it is effectively shortened then we may need to retune the car’s timing advance on the dyno (for increased advance) to regain losses in duration of the power stroke (again this against popular thinking of never to advance timing on forced induction cars, if we have a shortened power stroke, or an application with signficant overlap then it may be necessary to do so).

So we see here that the end result here a lop-sided camshaft with a conservative duration, high lift cam on the intake side, and a normal duration, high lift cam on the exhaust with minimal lobe seperation angle and minimal (but not necessarily no) overlap.

 

The exception to the rule:

Sometimes people take a car that starts off with a 9000 rpm redline, has an 11.5:1 compression ratio, and a 280* duration camshaft, and an aggressive naturally aspirated-esque timing curve and decide to supercharge it for more power. One suck example is kleemann’s kompressor for the SLK55 AMG (which already makes 400 hp in normally aspirated form from an 11:1 compression ratio motor). In this type of application, if you use a more conservative cam, and dial out all the overlap, and increase the power stroke, in combination with an already high 11:1 compression ratio and a healthy amount of boost pressure (7psi or above) you will end up with a motor that produces extremely high peak cylinder pressures and those intense pressures and heat may easily start off a chain reaction of pre-ignition and detonation and you will find that no matter how much you retard the timing that the setup will end up both powerless and still not that safe.

In this case, I would consider RPM and compression my primary power adder, and my supercharger as my secondary power adder (that is unless I decided to change that and went ahead and lowered the compression ratio of the motor). In this case it is ok to sacrifice some supercahrger high rpm effeciency for preventing high-load & low-rpm detonation. Furthermore, to overcome the overlap inherent in this kind of high rpm normally aspirated powerplant it would be very advisable to use a centrifugal supercahrger that is capable of producing more boost and flow with increased rpm rather than a  roots type charger that will easily run out of boost and flow capacity (CFM) when facing an aggressive camshaft ‘leaking’ boost away.

 

Here is a great example of how cam tuning can affect supercharged power:

The car is a 1.8 liter honda motor equipped with:

  • Supercharger optimized big pirmaries and short runners Kamakazi header
  • A greddy 2.5″ SP2 catback exhaust system.
  • An LHT ported “S” supercharger inlet tube
  • An LHT ported intake manifold ( Non intercooled)
  • A Carbon fibre intake
  • A Jackson racing eaton M62 supercharger geared for 7.5-8 psi.

 

B18c5 with JRSC tuned

B18c5 with JRSC tuned

 

 

 

 

The black line is the baseline run with all of these modifications before tuning.

The blue line is the power acheived after a full tine (camshaft timing redone for reduced overlap, ignition timing re-optimized, and air fuel ratio optimized for peak power).

The red line is the same as previous but running open-header with no exhaust system. Obviously this last run shows that the 2.5″ exhaust is more than adequate for the 250hp power figure.

You can see on this graph that by reducing overlap and properly tuning the car the power peak not only increased by 25 horsepower, but more importantly shifted up by 1000 RPM’s due to increased supercharger high rpm effeciency from reduced overlap.

The Horsepower Calculator – Video 2 – Camshafts

The Horsepower Calculator – Video 2 – Camshafts

May 29, 2009

By 

We are excited to release the second in our series of How-To videos on using the horsepower calculator.

In this edition:

Taking a 1.8 litre Mercedes C200 Kompressor engine to 320 horsepower.

First scenario: With camshafts for a power peak at 6200 rpms.

Second scneario: With stock camshafts, keeping peak power at 5500 rpms.

 

Tuning your timing and timing trends

Tuning your timing and timing trends

October 15, 2009

By 

Transcript:

Hi , it’s Haitham again and this is another one of our.. how-to videos around the Power calculator on Supercharger Performance .com

What I’m going to talk about today…
is timing advance and tuning your ignition curve.

First we’re going to talk about some of the underlying concepts of ignition timing and timing advance

Then we’re going to look at some simulated timing curves

Then we’re going to summarize with some insights on how you can use this information to increase your horsepower by advancing or retarding timing, in the right places to gain more power.

First of all, let’s look at a 4 stroke engine animation …

This is top dead center… when the piston is all the way up the bore
This is bottom dead center … when the piston is all way down the bore.

Usually when when we talk about timing advance, we talk about ‘B.. T.. D.. C.. ‘ or before top dead center.

Usually the spark plug ignites the mixture before the piston reaches top dead center in the compression stroke.

Now the reason why we fire the plug ‘early’…
is that the mixture of air and fuel (and possibly watermethanol, or nitrous) takes some time burn…
and so the flame front takes some time to travel outwards and consume all of the air inside this top volume (comprised of the cylinder head volume, and the piston surface volume if the piston is dished)…

once the flame has consumed a large portion of the air fuel mixture… this flame, trapped between the piston and the cylinder head, creates ‘peak cylinder pressure’ and it is this cylinder pressure and expanding flame that pushes down on the piston making it rotate.

Now the trick here is that you have to synchronize the piston rotation, with the flame front burn rate so that you can hit the piston with peak cylinder pressure just after it cross top dead center and thus deliver ALL the force of the combustion into the rotation of the engine.

If you advance timing too much, you catch the piston on it’s way up and slow down it’s movement losing power
If you retard the timing too much, the piston outruns the flame front and very little power is transfered from the combustion into rotation

So there is a ‘perfect’ timing setting based on these two things:

piston speed: which is affected by rpm, and by Rod/Stroke ratio
flame front travel speed: which is affected by factors like mixture density, fuel to alcohol ratio, compression ratio…etc

Now let’s talk a little bit about the two main factors affecting timing advance:

The first is RPM. As RPM increases, the piston speed increases.

The thing is that the piston speed increases linearly with RPM … but the flame front travel speed only increases slightly with RPM due to more turbulance in the cylinder and a better mixture of air and fuel which allows the ‘fractal’ moving flame front to travel faster.

So going from 700 rpms to 7000 rpms, the piston increases it’s speed by a factor of 10, but the flame front only increases it’s speed by about a factor of 3.

So in a sense the piston is OUTrunning the flame front, and to re-synchronize the mixture so that we can catch the piston at top dead center we need to further advance the ignition timing.

To make up for this effect, the timing advance at 7000 rpms needs to be about 3 times the timing advance at idle and that’s how ‘mechanical timing’ came to be starting with a base timing of something like 10 degrees BTDC and growing out to 32 BTDC near redline if we’re talking for example about a large bore engine).

The second factor is mixture density. Which is typically measured by the car’s ECU with RPM, Flow and temperature sensors… But for this example we’re going to measure it in terms of volumetric efficiency since we can calculate that figure.

As the mixture increases in density, then so does the number of air and fuel molecules available for the flame front to expand outwards. This denser mixture allows the flame front to travel faster, as is typically the case with forced induction engines such as turbocharged and supercharged vehicles that cram more air and fuel into the cylinder.

If we leave this mixture alone at stock timing, then the air fuel mixture will out-accelerate the piston and catch it BEFORE top dead center which slows the engine rotation and exerts power rather than making it.

So as mixture density increases we retard timing to catch the piston once again just as it crosses top dead center. As the mixture density decreases, we advance timing to prevent the piston from outrunning the now slower moving… & less-dense mixture.

Of course there are other things that affect flame front travel speed besides mixture density…

such as:
octane rating (higher octane fuels burn slower)
the presence of burn accelerators such as nitrous oxide and oxygenated alcoholic fuels like ethanol and methanol,
or the presence of flame retardants such as water injection and high humidity.

Now that we have a basic understanding of timing curves, let me show you some simulated timing curves based on the 5.7 liter LS1 engine.

Now let’s talk about the advantages of knowing this information…

Dyno time
Different VE curves for modified cars
Not leaving any power on the table (nitrous or superchargers)

____________________________________________

Apexi sitcThe Apexi S-ITC is an older generation piggy back controller. The S-ITC stands for Super Ignition Timing Controller, and had a +/-15 degree advance/retard setting adjustable at 5 RPM points between idle and 7000 rpms.

At the time when this box was released, most timing controllers were either basic boost based retards such as the MSD BTM (boost timing master) or a fixed single externally triggered retard box for nitrous activation…etc

So, at the time, this product was much more advanced than the cruder forms of ignition tuning available by competitors. However, this product sold very poorly and was quickly discontinued.

The primary reason for the product’s failure was not the product itself, but rather lack of information in the general community about proper ignition tuning and the power potential that was being left on the table with un-tuned cars.

I hope that this how-to video here gives you a better idea about ignition tuning (since very few people actually discuss this aspect of supercharger performance and engine tuning in general). Even though the tools have changed over the years (and now we have full 16 X 16 timing maps that are 100% tunable to your desired timing), the basic theory remains the same, and the thirst in this community for this information is still there.

Introduction to piston design for forced induction engines

Introduction to piston design for forced induction engines

June 28, 2010

By 

There are many great articles online on general piston design, piston ring design, and how the design of OEM and aftermarket pistons has changed over the last decade.

 

What we will focus on today is the choice of a proper aftermarket piston for your street engine running a significant amount of forced induction using supercharged, turbocharged, nitrous injected or a combination of these power adders.

So what we have in mind today is a daily driven motor, running in the rpm range up to about 8000 rpms with up to 18psi of boost pressure, and experience all the typical operating conditions of a daily driven motor including cold starts, short warm up durations, conventional oiling systems …etc

Before we start talking about piston design I want to first spend a minute talking about the different sections of the piston that are of interest:

The Crown: Is the top most surface of the piston which creates the moving bottom barrier in the combustion chamber. This part of the piston is in contact with incoming airflow, burnt exhaust gasses, and is part of the combustion chamber shape.

The Ring lands: Are the reliefs cut into the side profile of the piston where the piston rings sit. The ring lands are typically taller than the ring thickness which allows the rings to move and rotate in the bore. It also allows combustion pressure to contact the entire piston ring top face inside the ringland pressing it down (and out in some designs) improving ring seal.

The Skirt: The piston skirt is the extension of the side profile of piston which controls the piston movement in the bore preventing it from wobbling around and controlling the angular forces present on the piston walls from the angular rotation of the crankshaft.

The Underside: This part of the piston is exposed to the crank case and houses the wrist pin (connecting the piston to the rod) and exposed to the engine oil in 3 ways:

  • Oil collected by the oil retention ring (the bottom most piston ring) is routed through holes in the side of the piston to the underside to drain back into the crank case.
  • Oil sloshing around in the crankcase due to the crankshaft counterweights dipping in and out of the oil sump as well as oil forced up through the connecting rod up to lubricate the wrist pin (on forced oil pins).
  • On engines equipped with oil squirters under the piston, where oil is squirted on the underside to help cool the piston mass for longevity or racing applications, which in some situations may also allow for an overall thinner crown without sacrificing the strength of the piston and while reducing the overall weight of the package.

When it comes to choosing the right pistons for your street car on boost there are five aspects to look into:

1- Construction
2- Design
3- Coatings
4- Other considerations

1- Piston Construction:

For a street driven application, you’re looking for primarily a forged piston with a high silicone content in the range of 12% to 16%. The high silicone content in the piston improves thermal management in the piston and reduces the overall expansion of the piston in the bore when heated due to boost and power.

This reduced expansion means that you will not need to use undersized pistons (that will grow to fill the bore as they heat up) and engine will not have large tolerances causing piston slap at cold starts and long warm ups in cold weather, which is ideal for street applications.

Furthermore, most modern engines come with high volumetric efficiency from the factory (for example the new mustang 5.0 engine in 2011 will come with 412hp stock compared to a much lower 165 to 205hp -depending on the actual model year for the older 1980s ford 5.0).

Having engines now producing roughly double the power that they were producing just 15 years ago, and having the potential of further doubling that power figure with nitrous injection or 15psi of supercharged boost, then care must be taken to making sure the piston ring lands are anodized for reduced micro-welding between the piston and its rings under the increased heat and pressures from forced induction.

2- Piston Design:

As mentioned earlier, the top of the piston (the crown) is both exposed to the incoming airflow, as well as constitutes the bottom of the combustion chamber.

The piston crown during the intake stroke :To take swirl one step further, certain piston manufacturers have equipped their pistons with swirl enhancing crown faces either equipped with circular grooves or dimpled impressions on the piston crown. These groves and dimples are designed to promote increased swirl in street engines and have been shown to further improve torque delivery by another 4 to 5% over stock figures. Similarly, high compression pistons that gain compression through a very sharp protrusion in the center of the piston will reduce disrupt swirl in the chamber and lower combustion efficiency, although the increase in compression (at 3 to 4% per added point of compression) can negate this loss.

 

high swirl engines continue to tumble the air inside the bore

high swirl engines continue to tumble the air inside the bore

 

dimpled top pistons

Dimpled top pistons and groove top pistons improve airflow swirl and tumbling

 

 

Custom made dimpled top pistons for similar effect

Custom machined dimpled top pistons for similar effect

piston squish

 

 

Not all cylinder heads are hemi(spherical) heads. In this application for example a piston with a kidney shaped dish and a raised outer edge will give better results than a flat or symmetrical hemi-style piston

Not all cylinder heads are hemi(spherical) heads. In this application for example a piston with a kidney shaped dish and a raised outer edge will give better results than a flat or symmetrical hemi-style piston

Asymmetrical piston for a hemi head, notice the lip that goes around the entire out rim of the piston to squish air towards the central spark plug

Asymmetrical piston for a hemi head, notice the lip that goes around the entire out rim of the piston to squish air towards the central spark plug

 

combustion profile

Combustion profile showing the irregular distance between the spark plug and the edges of the boundaries combustion chamber on a typical flat top piston

 

piston cutaway showing the distance between the valve relief and the first ring land which should be maintained at 0.2"

piston cutaway showing the distance between the valve relief and the first ring land which should be maintained at 0.2″

 

 

If you’ve never seen a piston machined down before … watch this video:

 

visible here: piston crown with thermal barrier coating, side skirt with friction reduction coating, forced side relief (FSR) piston with reduced side skirts for very high rpm operation (typical on race engines and motorcycles)

visible here: piston crown with thermal barrier coating, side skirt with friction reduction coating, forced side relief (FSR) piston with reduced side skirts for very high rpm operation (typical on race engines and motorcycles)

 

 

visible here: bottom of the piston with oil shedding coating

visible here: bottom of the piston with oil shedding coating

 

For more information on tuning your engine for a high-cycle lifetime of abuse... be sure to checkout The Tuner Mastermind

 

The piston crown during the compression stroke :

 

This brings us to a very important point which is engine ‘squish’. The use of asymmetcrical piston crown design not only continues the swirl process initiated in the intake system, but more importantly having an asymmetrical piston crown forces the air to rapildy move towards one side of the combustion chamber, especially as the piston approaches top dead center. This squish effect near top dead center can be used for several advantages:

  1. Getting a good air and fuel mix for more efficient combustion.
  2. Moving the air and fuel mixture closer to the spark plug for easier ignition.
  3. Reducing the distance between the tip of the spark plug, and the farthest pocket of air and fuel mixture that needs to be burnt. Reducing the flame front travel distance builds cylinder pressure faster in the chamber which reduces timing advance requirements at lower rpms, but also, maintains more torque delivery to the piston as rpms increase (and as the time that the piston spends between top dead center and 17* ATDC) starts to shrink rapidly compared to flame front travel speed past a certain rpm point, as well as for engines with a shorter rod to stroke ratio with faster piston acceleration away from Top Dead Center.
  4. Reducing the probability of detonation and uneven combustion from the better air and fuel mixture and better heat distribution.
Knowing these advantages during the compression stroke to shaping the piston top, then the typical flat top pistons of late become obviously obsolete. The best piston choice is actually a D shaped ‘reverse dome’ piston which combines an asymmetrical crown design with a thicker crown height that either mirrors the combustion chamber shape (as seen look into the bottom of the cylinder head) or with a thicker out ring on hemispherical head. The whole point here is that the air fuel charge is compressed in a tighter pocket area around the spark plug location, and moved away from the far cylinder walls. Then, to maintain the same compression ratio (even with this thicker crown height) the crown area around the spark plug is dished by the right amount to bring the total volume of the combustion chamber + the piston dish to be the correct volume for the proper engine compression ratio.

 

Furthermore, on some applications we can take this one step further by milling down the cylinder head (or using a different cylinder head casting with shallower combustion chambers) which brings the spark plug down deeper into the bore, and offsetting the loss of combustion chamber volume with further dish in the piston crown. Bringing the air and fuel pocket closer to the spark plug, and bringing the spark plug closer to the center of the combustion chamber formed between the cylinder head contours and the piston crown contours boost engine efficiency, reduces detonation probability, reduces timing advance requirements, and promotes increased efficiencies at higher rpms as described earlier.

Finally, for a forced induced motor, care must be taken that the crown thickness after all modifications to the piston crown are complete (such as enlarging the valve reliefs for oversized valves, or increasing the piston dish for a shallower cylinder head and a lower spark plug position as described earlier) is still at least 0.175” thick with a good margin of safety being around the 0.200” mark for forged aftermarket pistons. Another thing to note is that typically enlarging valve reliefs not only reduces crown thickness as a vertical measurement, but also diagonally reduces the distance between the valve relief and the primary piston ring. This is even more evident on newer high efficinecy (low emissions) engines that come from the factory with a raised primary compression piston ring (or a reduced distance / lip between the piston top and the first ring land).To summarize:

 

When choosing an aftermarket piston for your motor, look for a reverse dome piston top (rather than a flat top or typical dish type piston) with dimpled flat surfaces for better mixture, and still having at least 0.2” material thickness throughout the entire crown of the piston.

If the piston I just described does not exist, a thick piston (high compression) piston can be machined down to make the piston I’m describing by someone who knows enough about this to do it properly (or by requesting a custom style piston from the piston manufacturer themselves).

3- Piston Coatings

Investing the money in getting your pistons coated has several benefits including:

  • Increased power
  • Reduced emissions
  • Better response
  • More resistance to catastrophic failure

The best combination of coatings are as follows:

  • A thermal barrier coating on the piston crown
  • A friction reduction coating on the piston skirts
  • An oil shedding coating on engines equipped with oil squirters in the crank case

The thermal barrier coating gives a more consistent finish to the top of the piston crown. It helps reflect heat into the combustion chamber, rather than dissipating it through the piston materials and thus improves combustion speed and the completeness of the combustion process. However, this increase in combustion temps and trapping the power rather than dissipating it does require reduced timing advance, but will as stated earlier, pay back dividends on higher rpm motors or on engines with short rod/stroke ratios where piston acceleration away from TDC becomes a problem for power transfer into the pistons at higher rpms.

One thing to note here is that since the thermal barrier coating improves torque delivery by accelerating the burn rate inside the engine, it can be used to boost torque output on cars with centrifugal superchargers or large turbos to give better response before the boost builds.

Overall, it may seem like it’s disadvantageous to trap more heat in the chamber and that it possibly reduces the octane, boost, or timing limits of the motor but this is not true. The increased heat can be counteracted with timing reduction without power loss (since the burn rate is maintained) and the added advantages are that the thermal coating helps spread the heat out over the entire crown area of the piston, thus protecting any thin or weak spots from being pummeled to failure. Also in the rare event that you do have some minor detonation in the engine due to high load, a bad fill of gas, or some other factors, the thermal coating prevents piston pitting due to minor occurrences of detonation, and thus it prevents the creation of hot spots on the piston crown which could have become hot-beds for further detonation and a prevented runaway towards total piston failure!

Seems like a fair trade off of some timing advance for increased longevity and increased high rpm efficiency.

The low friction coating on the piston skirt reduces frictional losses between the piston sides and the cylinder walls. This protects the pistons from damage and scuffing on cold starts, if the engine is overheated or overboosted (and the piston expands due to heat), and during oil starvation conditions (high cornering G’s, coild oil, first crank after a rebuild).

Reducing friction in the engine delivers more horsepower to the crank, improves the engine’s operation near redline, and gives the engine crisper response. One study showed that using lower profile skirts, with proper friction coating, as well as lower friction wrist pins can reduce the total engine internal friction by 40%…

So, something as simple and non intrusive as coating your piston skirts is definitly worth the effort, especially on boosted street cars that need to run a full skirted piston (as opposed to naturally aspirated motorcycles that will more likely run a forced side relief piston which features a longer skirt in the primary axis of the piston motion as the connecting rod movement shoves and pulls the piston against the bore on the upwards and downwards strokes… and a short or no-skirt in the axis 90* with plane of the connecting rod’s movement).

Finally, oil shedding coatings on the bottom surface of the piston help evacuate oil off of the piston faster. This helps keep the piston lighter and faster moving in its rotation, however since oil is used to cool the piston bottom and increase its longevity (especially in motors that will experience high cycles as we will explain later), then there is a debate as to weather this coating is beneficial or detrimental on different engines.

Engines with oil squirters get plenty of oil volume delivered to the bottom of the piston at a constant stream of flow. These engines can do with a reduced duration for oil clinging to the bottom of the piston.

On the other hand engines that rely on the crankshaft counterweights sloshing in the oil sump and indirectly sending oil up to the pistons to cool them (and up to the wrist pins to lubricate them on engines without a force-lubricated style connecting rod) could use with the oil clinging to the piston bottom for a longer duration.

If you are doing a full rebuild, my recommendation would be to both coat your pistons AND install oil squirters. Otherwise, choose weather or not to use the oil shedding coating based on weather you have a dry sump, wet sump with squirters, or wet sump without squirters oiling system.

4- Other Piston Design Considerations

As mentioned earlier there are other considerations to choosing your piston design which I have eluded to earlier.

Even though most people judge engine life based on mileage, performance engines are more accurately judged on cycles.

For example, an engine can run for 100 continuous miles at 7500 rpms in 1st gear, or at 1500 rpms in 5th gear…. the same engine could be tracked every weekend (spending a healthy portion of its life in the higher rpm ranges) or cruised on a highyway commute to and from work.

Even though these two engines have the same mileage, they have lived through a different number of engine cycles. Engine cycles is what determines the amount of continuous (or accumulated) stress both on your pistons (for thermal management) as well as on your piston rings (for wear management).

The advice given here is primarily for dual purpose vehicles that are both street cars but will see occasional or repeated track use.

Vehicles that will be used primarily for racing, require a thicker crown for better thermal management, will probably use a lower silicone content piston (with much larger piston to bore clearances to allow for the thermal expansion of the piston after it stops slapping and warms up in the bore, and will definitely have lower ring height for the primary compression ring (which reduces the operating temperature of the ring from around 600*F to around 300*F) as well as using a thicker compression ring that is less likely to distort or fail under continuous sustained high rpm abuse (think about a car in Nascar racing that does the entire race over 5000 rpms…)

These cars that are designed for ‘standing mile races’ as I like to call them or long term endurance racing will also have to be tune differently as I have a complete longevity tuning chapter in The Tuner Mastermind.

However, for most street vehicles running up to around 18psi of boost, and having dual street / track duty… then follow exactly the piston recommendations detailed here and you will have a great combination of torque, efficiency, detonation resistance, and reliability.

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