What fuel should I run in my 99 ZX2? The manual says it has 9.6:1 compression ratio, is that on a borderline 89 level? I want max power/fuel milage. My mom's truck has 9.25:1 and it runs like CRAP on 87oct (3.0) V6. It runs on 87 but.....?
Probably 87. You can't judge what kind of fuel to use on compression ratio alone. Older engines required higher octane fuels at higher compression ratios because of less efficient combustion chamber designs that didn't promote even combustion. Fuel and spark are also far better controlled than they were in older engines as well. Put all this together and you've got a higher compression engine that is less prone to detonation on a lower octane fuel.
The 3.0 V6 is an exception to the rule as Ford can't seem to fix the detonation problems that plague this engine. My guess is that the FFV calibration just doesn't get along well with 87 octane gas since any kind of Methanol blended gas is going to have a naturally higher octane. There is *supposed* to be a sensor in the fuel line so the EEC can tell when a methanol blend is being used and changes the calibration accordingly.