Originally Posted by montreal red
stock boost pressure on the 2.5L 4cylinder from the STi is 14.5 psi!! thats a lot of boost on that little engine. stage 1 tune brings about 17 psi. and the claim is 40hp gain at the crank. havent dyno'd this to verify yet but others have done the same and seems to be true.
so i guess Beemw335 is right, 12whp for each psi is a good rule of thumb.
Yup. That is pretty much how it goes at this level for the size of engine and mods we do.
Originally Posted by M3 Montreal
Yeah NA engines require a lot of mods for smaller gains.
On my old E92 M3 I added 55 whp (most stock M3's dyno at 345 whp on a wheel hub dyno) which got
Me to a tad over 400 whp by doing header back catless exhaust, pulley and ECU tune mated to catless system.
Turbos are fun but once you've gotten used to a fast responding engine like the M3's I just can't stand any form of lag anymore when I drive a forced induction car.
Nice gains. Dropping the A/C, new pulleys, flywheel, headers, air box and easy breathing 3" exhaust got me an extra 36hp/11tq. It's pretty hard to get anything extra out of the M3 without radical surgery. I've done all that there can be at my level. I either add small supercharger (6psi), update the existing S54 (increase bore, cams, head, blah, blah, blah), or replace it altogether with something cheap like and LS1 and transmission (
...). Let's see what next year brings LOL. I may just go broke first haha