my GSR?

[Batlground]

1) JDM ITR Pistons (P73-00, not P73-A0) .25 over
--- That should net you around 11.45:1 C/R. The only thing higher would be PCT pistons (jdm CTR), which would put you close to the pump gas threshold at around 12.1:1

- You could choose to go with forged pistons at a higher C/R if you want to run an octane booster or race gas.

and when will people realize that CTR pistons are MUCH HIGHER COMPRESSION that whats published on the internet.

P72 head/B18C Block

STD = 12.924594026551906
.25 OS = 12.989047869209281

[allmotoronly]

and when will people realize that CTR pistons are MUCH HIGHER COMPRESSION that whats published on the internet.

P72 head/B18C Block

STD = 12.924594026551906
.25 OS = 12.989047869209281

I calculated the compression to be 12.042422511586593:1 using the fact that CRT pistons have a 8.63cc dome, using the B18C1 piston to deck height of .030, P72 head combustion chamber of 41.60cc, oem B series head gasket thickness of 0.0290, and of course 81mm bore, 87,2mm stroke. I don't know where you are getting 12.92:1... I do my own math, but I do use some measurements found on the internet (combustion chamber cc, piston to deck height). The only reason I can figure that I am wrong about the compression ratio is if one of these measurements is wrong. Tell me what I'm doing wrong so I can fix it. Dont just say I am wrong.

[Batlground]

I calculated the compression to be 12.042422511586593:1 using the fact that CRT pistons have a 8.63cc dome, using the B18C1 piston to deck height of .030, P72 head combustion chamber of 41.60cc, oem B series head gasket thickness of 0.0290, and of course 81mm bore, 87,2mm stroke. I don't know where you are getting 12.92:1... I do my own math, but I do use some measurements found on the internet (combustion chamber cc, piston to deck height). The only reason I can figure that I am wrong about the compression ratio is if one of these measurements is wrong. Tell me what I'm doing wrong so I can fix it. Dont just say I am wrong.

Yeah, most people forget about piston to deck height which with pct's is about 0.0(at least on b18b block), since the pct's are taller by about .03''...

CTR pistons are taller than other B pistons, so you forgot to take that into account

[allmotoronly]

Yeah, most people forget about piston to deck height which with pct's is about 0.0(at least on b18b block), since the pct's are taller by about .03''...

CTR pistons are taller than other B pistons, so you forgot to take that into account

Ok I get what you're saying. So are the PCT pistons the only ones that have a 0.00 piston to deck height? I think that most other B series pistons have .030 piston to deck height.

damn jdm stuff always throwing me off. I have acura and honda clearances and specs on most usdm engines, just not the jdm engines... I just figured the piston to deck height was pretty much the same on all B series pistons...

edit: I did a few more calculations. I came up with 0.07 piston to deck height on the PCT's. Is that about right?

I got 12.989047869209281 for .25 oversizes pistons.