82 turbo z Posted March 7, 2011 Share Posted March 7, 2011 hey im in the middle of my overhaul for the motor and ecu stuff and only thing stopping me right now is pistons. im boring .30 over and want forged pistons. i called je and they wanted 1100 for a set and i know for sure i can get them cheaper then that but i was wondering if i run flat top forged pistons with a 1.5 or 2mm headgasket will my compression stay the same or raise/lower? ill be running about 10 pounds with innercooler and lots of supporting mods and tune. thanks Quote Link to comment Share on other sites More sharing options...
stprasinz Posted March 7, 2011 Share Posted March 7, 2011 I'd run the flats with factory thickness head gasket at that boost level... heck, I'd run 10-1 if thats all the boost you are gonna run... What do flat tops net thats not even 8.5-1 with a 1.2mm hg. go up to the 1.5 drops it to 8.3-1 and a 2mm will drop down to a just a hair under 8-1...... and yes thats with the flat tops... at that boost level you could run a much thinner head gasket and be safe... (.8mm gives a 8.8-1) many engines are running 9.5-1 and boosted.... so 10 psi on that low compression of a setup would be fine! Quote Link to comment Share on other sites More sharing options...
Jordon Posted March 7, 2011 Share Posted March 7, 2011 hey im in the middle of my overhaul for the motor and ecu stuff and only thing stopping me right now is pistons. im boring .30 over and want forged pistons. i called je and they wanted 1100 for a set and i know for sure i can get them cheaper then that but i was wondering if i run flat top forged pistons with a 1.5 or 2mm headgasket will my compression stay the same or raise/lower? ill be running about 10 pounds with innercooler and lots of supporting mods and tune. thanks Well it all depends, it would definitely help if you could supply the head casting number e.g. n42, p90 etc. Without that information it is pretty hard to help. But from my calculations, with a P90 head a .300" (7.6mm) overbore and a 2mm head gasket you will be just below 8:1, therefore you should have a slightly lower CR. This calculator helps alot. http://www.atlanticz.ca/zclub/techtips/calcs/engine%20builder/index.html Quote Link to comment Share on other sites More sharing options...
stprasinz Posted March 7, 2011 Share Posted March 7, 2011 well, I was going on the fact that he had p90.... didn't think of that. and I used another one.... http://www.ozdat.com/ozdatonline/enginedesign/ Quote Link to comment Share on other sites More sharing options...
82 turbo z Posted March 7, 2011 Author Share Posted March 7, 2011 sorry guys i have a p90a head. i think i found out what im going to do now thanks im just running 10 pounds right now for the break in and after ill be pushing 13 till i get a bigger turbo so all that should be good Quote Link to comment Share on other sites More sharing options...
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