I am in the process of rebuiling my gsr and i was curious how high of compression would be safe with the stock P72. the only tuning tool i have is a ericks fpr, with a b&m gauge. and an innovate lm-1 wideband o2. right now i am running a chipped p28 running a JUN program, i really like the program cause it operates the secondaries in the i/m but i don't like the fact that it has no rev limit, or if it does i haven't found it yet, also i don't think it senses knock either.

here is my setup:

B18C1
81.25mm JDM ITR Pistons
JDM ITR intake Cam
Milled head, i am not sure how much the head is milled cause i haven't gotten it back from the machine shop yet. i told them to take as little as possible when they resurface it, just enough to make it flat

any feedback would be great, thanks in advance

 

I would retune the ecu for that motor. it would be a shame to spend all that time on the motor and have a sub par ecu to run it. try to make it all matched.

 

Luke, while you know it would be better to run a custom map, let me remind you of Josh's car.

Josh ran p73 pistons with a milled head on his stock ecu. He had fp at about 40psi when I put it on Chris's dyno about a year ago. His a/f stayed flat at about 13.8:1 across the board.

With you access to the dyno immediately on startup, I really wouldn't sweat it man. **** if you have a wideband, just crank the fuel up until it's Kosher.