Originally Posted by Mike@GTM

I see that some of you guys are really confused on the relationship between power, torque, octane, boost, compression ratio, intake air temperature, barometric pressure, volumetric efficiency, air/fuel ratio, detonation, cylinder pressure and ignition timing. As you can see there are a lot of variables to take into account. A number of you get it and some of you look at one or two variables and jump to conclusions with expectations that don’t factor everything in. Then there’s another small minority that over analyze everything.

Ultimately, I have one word for explaining everything here: BALANCE.

Balance between all the variables in the equation for horsepower.

Balance in the analysis of the variables. Don’t oversimplify, and don’t over-analyze.

Balance in the power you make at the wheels on a dyno and power you can actually put to the pavement. Power is nothing without control.

Remember back in elementary school math class when the teacher would say: “what you do to one side of the equation, you must do to the other side of the equation”? Well, the same principal applies to engine dynamics. That’s where the “balance” comes from. Take away octane and you must take away either boost or timing or both (all other things being equal) or suffer the consequences (detonation, blown motor). By the same token, if you add a bunch of octane, but cannot add the boost and/or timing, then you don’t have a balanced equation and you will be limited to the least common denominator. Remember; just because you increased the detonation threshold you are not going to magically make more horsepower. Especially if the ECU is reading high intake air temperatures and is pulling timing on its own…regardless of the fuel octane.

Yes, California gas is horrible. Let me explain how bad it is. A friend of mine tuned his car in New York and when he moved to California, he had to pull 7 degrees of timing to stop detonation! 7 degrees is very significant and depending on the engine and setup can be around 40whp.

There’s another thing I’d like to point out here. We are talking about a supercharger system that generates boost based on engine rpm and pulley size. If you go really big on the pulley, you simply aren’t going to make much boost, and you are going to build boost at a slower rate. If you go really small on the pulley, then you will make more boost and build boost faster. A supercharger system is, for all intents and purposes a “Set it and forget it” kind of system. You can’t just push a button and step up the boost for when you decide to go to the track and put race gas in the tank.

If you want a lot of adjustability and horsepower, then a twin turbo system with a boost controller is a much better way to go. It’s simply a more flexible system.

Here’s the bottom line. If you are going to be doing the Stage 2 Supercharger and running it on 91 octane gas, we recommend a 96mm pulley which will put you at 8 – 9psi and 450 – 470whp.

If you are going to be running 93 octane gas OR 91 with water/methanol injection, then we recommend a 92mm pulley which will put you at 10 – 11psi of boost and 500+whp.