I need some help with compression ratio! I have a b18c1 with type r pistons, told that would put me @ 10:9:1? also am using skunk high comp. valves, and a spoon headgasket! any one have any comments to what this would put me @ and I am trying to get 12:1 n/a please help and if I would have to mill the head and how much to mill it?

 

There are much bette people to ansewer this, I don't know specifically what your static CR is going to be with that combo, but I'm not sure it is neccessary to mill the head if you are using stock GSR cams. From what I hear the max CR that will do you much good is 10.8/1 on stock GSR cams. Also, when you mill the head you can get into valve clearance issues with the pistons depending on your cams and how much you mill it. For stock GSR cams it sounds like your pistons and headgasket will do the job.
I would definately talk to an experienced engine builder BEFORE you buy parts though. They can certainly judge better-than-I.


[Modified by thirdvector, 8:19 PM 1/27/2003]

 

USDM ITR (P73-A0) pistons straight into your block are going to yield ~0.2:1 over a stock ITR motor due to the difference in the combustion chamber volume... Your P72 head has a CCV of 41.60cc's where as the PR3 (B16/ITR) head is 42.70cc's... I don't know your headgasket thickness but this it what your motor will be at with an OE 0.029" headgasket... normally for every 10/1000th's you take off you'll get an increase somewhere around ~0.25:1... A single layer headgasket being ~0.009" and a 2 layer ~0.019".... I really wouldn't try to achieve this with 12.0:1 w/ ITR pistons, that's what i assume you are talking about... If you have PCT slugs then you'll already be over your 12.0:1 and PR3's or P30's will put you right around where you wanna be with a your headgasket etc... I wouldn't mill the head unless you just need to deck it either... That's just the way i build motors tho... If you want high/low compression do so via pistons... And whenever possible I would just stick with an OE headgasket... I really wouldn't only use them on big bore motors and boosted motors... Then something like a Cometic will be better... Hopefully this helps but let me know if you need anything else... Peace