Stock EVO comp ratio is 8.8:1

Most built motors are 9.0:1 or higher.

 

mine is 10.5

 

Yes. Its common to run 25-30 psi on pump gas (93oct or 91oct). I personally run 28psi on 91oct.

In the early days of the EVO in the US, tuners and everyone used to believe in only running 21-23psi on pump gas and used to believe you "needed" head studs for above 25psi. But after ECUFlash came out in 06, people started exploring the limits of boost more, and most peopel usually run 24-26 on stock turbos and 25-30 on upgraded turbos on pump now. We also have people boosting those high boost number, making 500+ on stock head studs now too.

Last, since the pressure in the combustion camber gets in the high hundreds ie 700-800psi and actual detonation adds a spike of a couple hundred psi, adding 6 more psi (22psi to 28psi) is really insignificant in the whole scheme of things.

 

It really is amazing how much boost you can shove into this engine haha almost 30psi on pump on a stock block is really impressive. Engineering genius.

 

Yeah the stock block 4g63 factor is amazing. A 4b11 would eat itself lol