Kenne-Bell Tech Facts

[Steve03GT]

Although the following info is supercharger related, it does share a lot of interesting, basic, forced-induction principles I found to be worthwhile. I hope you do to.

http://www.kennebell.net/faq/faq-answers1.htm
[i]What parameters determine how much boost my engine can run on 92 octane? Good question. One of the top 3 most commonly asked.
COMPRESSION RATIO - Lowering the compression ratio allows the engine to run more boost with the same octane. For example, 8.0:1 vs 9.5:1 can tolerate another 3 psi. 3 psi gives 38HP. The 1.5 lower CR loses 3% (2% per point) or around 9HP in a 300HP engine. That nets 29HP (38-9=29). Now you know why OEM's use low compression ratios on supercharged engines.
AIR CHARGE TEMP - The supercharger itself determines how much boost the engine will accept. Some superchargers require an intercooler. Others, such as the Kenne Bell, don't need intercoolers because the discharge air temp is cooler. 1 psi boost increases supercharger air discharge temperature 10°-20°, depending on supercharger type. A 6 psi "rated" kit usually requires 8 psi "total" boost (+2 psi to overcome inlet and outlet losses). Consider two 8 psi superchargers: 8x10=80°, 8x20°=160°. The 160° supercharger should use an intercooler. An air to water intercooler will lower that 160° to around 80° (160°-80°=80°) or the 80° temperature of a more efficient supercharger without an intercooler.
BOOST - Both higher compression ratios and boost increase cylinder pressure and demand higher octane fuels to eliminate detonation. Fuel octane determines the amount of boost an engine will accept. Kenne Bell runs 6-7 psi on all our Ford, GM, Chrysler and most other kits with our Twin Screw superchargers. One octane will support one psi of boost. Example: If fuel octane is 94 or you add a can of NOS Octane Booster you can typically run 8 psi.
IGNITION TIMING - Retarding ignition timing will allow the engine to run more boost but not without a penalty. 4° retard=16HP.
AIR FUEL RATIO - You can't make horsepower without fuel. Richer air fuel ratios reduce power but permit higher boost levels on a given fuel octane. Leaner ratios make more power but need lower boost so a lean mixture with high octane makes the most HP. We thoroughly understand all the parameters of supercharging. Supercharger kit tuning demands ignition timing, air fuel ratio, fuel octane, boost, compression ratio, discharge temperature and supercharger parasitic losses all be carefully considered in the design.
What causes detonation? 1. Lean fuel mixture, 2. low octane fuel, 3. excess boost, 4. lack of fuel, 5. advanced ignition timing, 6. vacuum leak, 7. "hot" spark plugs, 8. overheated engine, 9. excessive inlet temperature (underhood filter).
Why does Kenne Bell use a 6 rib belt to drive the supercharger and others use an 8 rib belt? Because our Twin Screw supercharger has less parasitic loss than others and therefore requires less HP to drive - which means the engine develops more HP with a Kenne Bell.
Do I need an adjustable fuel pressure regulator? Unless you're playing with an '86-'93 Mustang, don't bother.
What is the most ridiculous aftermarket product? Hands down, it's the "little intake fans" and the "throttle body spacers" with the bore grooves. Right there on the list has to be those "underhood exposed filters" that suck in 200° underhood air instead of ambient (70°-100° air from the fenderwell). 10° air temp rise is -1% HP. That's how dynos are calibrated for temperature changes. Does anyone really believe that all those OEM manufacturers designed expensive plastic inlet systems - for the last 20 years - that pull cool air from the fenderwell, hood or grill because they didn't have anything else to spend their money on? Then there's those "factory calibrated" mass air meters that do not use a chip or re-calibrated processor with oversize injectors. They unwittingly reduce the voltage signal to the mass air meter to compensate for the larger injectors at WOT but they neglect all the driveability issues. The result is over advancing timing, lean mix

[don668]

Interesting article. If you look @ "tech info Chrysler", they get into airbox restriction (or lack there of) and underhood cone filters.

[Steve03GT]

quote:Originally posted by don668

Interesting article. If you look @ "tech info Chrysler", they get into airbox restriction (or lack there of) and underhood cone filters.

I saw that. Hopefully that only applies to those filters which aren't shielded from the engine compartment heat; luckily my new AirAid is.