HI guys, I have a quick question, Im building my b18c1, and just got a complete built gsr head and valvetrain from portflow, I was thinking of runnin p30 .50 oversized pistons from rs machines on my block, with oem headgasket, which would put me about 11.5-11.7 CR, the other day I went to a shop where there was this tuner, and I told him about my plans, he said to get CTR pistons if I want to run that kind of CR because with the port and polished head work, that be knocking about .5 from the CR.

Normally with CTR pistons i'd have 12.2:1 CR but because of the P&P head I'd be running around 11.7; this is what the guy told me but I wasnt that sure, tried doing a search but nothing came out.

 

Unless Tom opened up your combustion chambers, your compression ratio will be unchanged. Stick with the P30 pistons; PCT pistons are not great.

 

1) Don't get hung up on compression. Ask you self this question, does higher compression make your head flow anymore? Compression is a 2nd order effect. Having a higher flowing head is what is actually important.

2) Don't switch to CTR pistons in a GSR, there are many reasons not to. Search you find the answers as to why.

 

Im still also debating if I should go with Skunk2 pro1 or pro2 cams... what you think?

here's the setup:

Edelbrock 65mm TB
Edelbrock performer X IM
Complete built head and valvetrain (portflow)
P30 .5 oversized pistons
GSR rods
Balanced crank
Hytech Replica Header



Modified by Eg6DR at 11:27 AM 3/6/2008

 

hmm .. if it was my setup , id choose pro1's . I would think the Pro 2's would perform more efficiently with a 2.0L