240z_808 Posted August 19, 2008 Share Posted August 19, 2008 i've been doing some searching and i just had a quick questions. using the vo7 crank, 73 240z rods, 89mm arias pistons (4.2cc dome), 1mm head gasket and a p90 head; i've calculated a ~8:1 compression ratio. i'm trying to get something closer to a 10-11:1 compression ratio. i know this is possible using a smaller cc head, but, from what i've been reading the p90 flows much better than the e-88/n-42. i guess what i'm trying to ask is, is it better (in regards to hp and torque) to use the p90 head at a lower compression or to used a smaller head (e-88, etc) at a higher compression? thanks! Quote Link to comment Share on other sites More sharing options...
naviathan Posted August 19, 2008 Share Posted August 19, 2008 You can get closer to that goal if not achieve it using flat top pistons. Quote Link to comment Share on other sites More sharing options...
evildky Posted August 19, 2008 Share Posted August 19, 2008 custome pistons, will get you any ratio you want Quote Link to comment Share on other sites More sharing options...
240z_808 Posted August 19, 2008 Author Share Posted August 19, 2008 ok, here's what i've got so far. i'd rather not have to do the p90 head shave mod if i can avoid it. *f54 block *p90 head *1mm headgasket *v07 crank *240z 9mm rods *arias KA24E domed pistons (89mm, 1.34 c/h, 10.4cc dome) bore diameter: 3.50 stroke length: 3.26 head cc: 53.6 head gasket: .039 (1mm) head gasket bore: 3.50 piston to deck clearance: .023 this yeilds a 3.08 displacement and a compression ratio of 10.7:1. my question now is, with these arias pistons, will the piston to deck clearance or piston deck height still be .023" (.6mm)? and because of the positive deck height + the domed pistons, will i have adequate valve clearance with the stock p90? Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 19, 2008 Share Posted August 19, 2008 valve clearance is something dependent on camshaft selection and actual assembly and testing on the engine. 'clay your pistons for valve clearance check' is the term used in the old days. that will only be answered by assembling your engine and checking it. if clearance is inadequate, have the piston heads flycut for clearance. that's what the trial assembly is designed to sort out. Quote Link to comment Share on other sites More sharing options...
Soundmasterg Posted August 19, 2008 Share Posted August 19, 2008 Which crank is the v07 crank? Greg Quote Link to comment Share on other sites More sharing options...
z-ya Posted August 20, 2008 Share Posted August 20, 2008 This is what I'm building: V07 crank KA24 89mm pistons L24 rods P90 head 0.6mm fly cut (gives stock 0.030mm deck height) KA24 2.8cc dish should be close to 0 with fly cut 1mm gasket CR should be close to 9.6:1 (good for street engine) Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.