I was curious cause i been asking around .. and people tell me it will actually lower my Cr to around 10.2? .. what will the cr be with USDM ITR and JDM piston on a b16a2 block and head.. And what will it be on a CTR piston on b16a2 block and head? cause i want to run around 11.5 so then i can NOS it.. thanx

 

First of all, I think 11.5:1 is too high for nitrous.
But it's your motor....

B16A pistons will NOT give 10.2:1 in your application. You are taking a 10.2:1 compression ratio, which is based on a 77.4mm stroke, and you are increasing the stroke by 9.8mm. This is what causes your compression to go up. Top dead center volume is generally the same, but bottom dead center volume is much greater.
I have never done the EXACT math for this, but I would say 11.1 or 11.2:1 would be an educated guess.

CTR pistons in a B16A will give you about 11.2:1 as well. This is a slightly different situation, because the CTR is a 77.4mm stroke as well, but it is only 10.8:1. You are getting more compression out of this because you are decreasing the TDC size now. The CTR rotating assembly(crank/rods/pistons), sit below the deck when they are in a B16B block. When CTR pistons are installed in a B16A block, the piston sits ABOVE the deck. Catch my drift?

For 11.5:1 you can do B16 pistons and mill 15 or so off your head. This will work in either situation..




[Modified by Mike K, 5:12 PM 10/12/2001]

 

11.5:1+nos=bad news

 

okay now i might no NOS it no more and just want to run a 12:1 CR ratio.. so will i need to run a 12:1 raito and whp and tq # i'll put down ?