what kind of compression ratio

[uglydogo]

I have a set of stock 03 cobra pistons. But was wondering what kind of compression ratio I can get away with on a boosted 4v.

[racrguy]

We'll need more info than what you've given.

[SC457A]

I have a set of stock 03 cobra pistons. But was wondering what kind of compression ratio I can get away with on a boosted 4v.

Stock Cobras are 8.5 to 1. I run 21 psi of boost with a Whipple. Very borderline with pump gas.

[uglydogo]

Im looking into putting different pistons in the short block im buildin. I was wondering, what kind of compression I can get away with

[5.0Thunder]

It depends on the amount of boost and what fuel you want to use. Higher compression ratios require higher octane fuel to utilize higher boost levels.

[racrguy]

I'd take it to a reputable engine builder if I were you. Don't take this the wrong way but I don't think you're ready to mess with the internals of an engine if this kind of question stumps you. There are so many variables and so little info, to give you an answer would be like trying to hit a 1" target with a shotgun at 200 yards and have all the shot hit the target.

[5.0Thunder]

What you need to do is either buy pistons that will "give" you a certain ratio, then figure out how much boost you can use with whatever fuel you want to use... OR Figure out a certain power goal, then decide how much boost it will take and what fuel to use, and buy pistons that have a ratio that will match up with those figures.

For example: with a stock 302 block, the compression ratio rests at around 9.0:1 so that allows for roughly 10lbs (experimentally obtained value) of boost to be added before you need higher octane than 93. If you decided to use E85, you can increase the boost and make more power, similar with race gas. If you buy pistons that increase the compression ratio to 10.5:1, it requires higher octane to run N/A so you can't run as much boost before running out of octane so you are forced to convert to E85 or use race gas (or a meth kit) with lower boost levels.

[Lone Star Performance]

We need to have power adder combo, Power goal, and what type of fuel you want to run. Meth?