DeusEx Posted February 7, 2005 Share Posted February 7, 2005 hey guys Looking to up the compression on my engine to unleash some of that Hp and the option atm appears to be planeing my P90 since it has already been portmatched and polished. Looking to plane 1 - 2mm from it. So i was wondering if anyone had done this to their P90 and if so what CRs did you gain? im at 190 per cyl atm which is about 8.5:1 i think. What issues car arise? better head gaskets? Stronger Valve springs? Valve/pistons clearence? Thanks guys Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 7, 2005 Share Posted February 7, 2005 http://www.geocities.com/zgarage2001/p90.html That should answer most of your questions. Try the search function too. Been discussed a lot. Quote Link to comment Share on other sites More sharing options...
DeusEx Posted February 7, 2005 Author Share Posted February 7, 2005 i did that, couldnt find anything on shaving it.... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 7, 2005 Share Posted February 7, 2005 Weird, I searched and couldn't find anything either. Then I searched for JUST .080 (2mm) and got this: http://forums.hybridz.org/search.php?searchid=29463 Quote Link to comment Share on other sites More sharing options...
DeusEx Posted February 7, 2005 Author Share Posted February 7, 2005 Ok the recomendation seems to be plane it .080 (2mm and shim it) easy enough. But i dont understand using longer 280z valves.....didnt the P90 come with them? and why would you make the valves longer isnt this inviting a meeting with the Pistons and Valves... Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 7, 2005 Share Posted February 7, 2005 The P90 had a deeper chamber, so it used shorter valves. When you put in the cam tower shims, this raises the cam away from the rocker arms. Installing the longer N series valves brings the end of the valve (and the springs and retainers and lash pads) back where they need to be with respect to the cam. The valves have a longer stem, but the head is the same so the extra sticks out the top of the head, not into the chamber. Alternatively you could get gigantic lash pads, but since N heads are a dime a dozen, most just use the longer valves. Quote Link to comment Share on other sites More sharing options...
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