Compression help

StreetEviL · Post by **StreetEviL** » Fri Apr 20, 2007 5:57 am

I have the 05' SXT factory compression ratio of 9.3:1. I am wanting to put first gen DOHC pistons in and mill the head .040 over. Can anyone tell me what compression ratio that will bring it up to. I can't figure the exact #'s off the top of my head, but I figured 11.1:1. If anyone can help. it would be appreciated! Also, I heard the 95 year model neon cam would net a small gain, might have to try it since I have one on my desk. I can tell a slight difference in size, when compared to mine.

neon12sec · Post by **neon12sec** » Fri Apr 20, 2007 6:58 am

you would have to cc your head after milling to get a correct compresion ratio number.

Post by **racer12306** » Fri Apr 20, 2007 9:35 am

guess you are planning on ditching your turbo

OB · Post by OB » Fri Apr 20, 2007 10:32 pm

you'd have to tell me the new swept volume of one of the cylinders with the dohc pistons first, but thats pretty easy to calculate.

StreetEviL · Post by **StreetEviL** » Sat Apr 21, 2007 1:18 am

When me and a buddy swaped DOHC pistons into his first gen with 9.8:1 compression, it brought it up to 10.28. So, I figured that the DOHC pistons would bring me with 9.3:1 to 9.7ish:1. Then mill the head for the rest of the vital compression. And yea, I ditched the turbo, oil seals blew. So I said screw it, and now it's for sale!

OB · Post by OB » Sat Apr 21, 2007 1:56 am

Compression math is based on precise measurements, so if you can get an exact amount on the cyl volume feel free to PM me and ill calculate it for you.