Just felt like sharing some numbers. Here is how I figured it out: Stroke= 75mm Bore= 97.5mm Head combustion chamber= ~49-50cc Piston dish= 20cc Headgasket bore= 98mm Headgasket thickness= .051"/1.2954mm Piston/Deck clearance= .015"/0.3809999999995885mm The final compression ratio should be around 8.375:1 Looks like a boost friendly number
What heads? What pistons? Wisecos use a 98.5mm bore. Stock EJ22T compression is 8.0:1. Stock heads, headgaskets with Wisecos is 8.5:1.
The stock EJ22T heads weren't 49cc, the WRX heads are which is what I assume he's using. With WRX heads and wisecos I had a CR of around 8.22:1. The wiseco dish volume was 22cc though IIRC which would lower the CR from his 8.37:1 a bit. And I'm not sure my deck clearance was .015 with the wisecos but they did protrude from the block. I'd have to look up my calcs again to see for sure.
Well, my memory fails me again. Eitherway, my calcs came to 8.22:1, so I'm not sure what changed here. Since my setup was the same.
DING! But that would have raised the CR, not lowered it. I went with the .051 instead I believe, because I was worried about piston contact.
^When you did yours, you used 24cc dished pistons. Wiseco must have changed their formula around or something... I found your thread on nasioc Wiseco pistons, 97.5mm and yes, they are 20cc dished (8.5:1) I'm using 01 2.5rs SOHC heads, should be between 49cc and 50cc Stock 22t heads I believe are 46.6cc, which is the main reason my cr is lowered. I'm not 100% on the piston/deck clearance, but if you play around with the compression calculator, its a small factor in the equation & .015" shouldnt be too far off of what it actually is.
My block, crank, and pistons are at the machinist getting bored and balanced. I will have em back by monday and i'll take some pictures to share
98.5mm bore. Also, when I bought my pistons, which was before Jason, Wiseco still listed the compression ratio on the 22T longblock at 8.5:1. In the end, does it really matter? You are probably still are going to use what you have planned anyways. Toiling over a tenth or two of your compression ratio is a waste of time. If it is a hair low, get a larger turbo.
97.5mm bore is .020" overbore, 98mm is .040" overbore.... not really worth arguing, so look it up: http://www.slowboyracing.com/sbs/sbr_product.php?productid=2720&cat=714&page=1 I'm not toiling over it, I wanted to share and learn some.
