High compression pistons vs. screamin' eagle heads

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#11

03-06-2010, 10:32 AM

gsxrboy96

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Quote:

Originally Posted by wickedevo

Any of you guys still around?... I'm looking at doing the same mods to my 87 Evo... SE heads andrews ev27 cam but was told to order 9.5:1 pistons... according to Wiseco's site the stock 8.5:1 pistons will give me 9.5:1 with the SE heads.. which I have read everywhere... but vtwinperformance.biz calls for 10.5:1 wiseco pistons for the SE heads and I've been told and read this will lead to starting issues or the need for reliefs....

But my buddy helping me with the build keeps telling me to order 9.5:1 pistons. is he confused ???(JE makes them) If stock 8.5:1 with SE heads will raise it to 9.5:1 will 9.5:1 pistons be raised to 10.5:1 with the SE heads?
someone help me settle this argument ????

Thanks

With a stock 8.5 to 1 piston, when you use s/e heads, your dropping about 9cc out of the chamber(compared to the stock head), therefore your compression would be raised nearley 1 point, so yes, a 8.5 piston would be a 9.5 with a se head, if your going to do pistons, i would reccomend the je pistons made for the s/e heads, they match the port exactly, also you have to be careful because of the short duration/timing of that 27 camshaft, you can easily run into detonation with around 10 to 1..... chad.

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#12

03-06-2010, 10:55 AM

wickedevo

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Thanks, It was Wiseco that called for the 10.5:1 pistons. with the SE heads on their website. Je does make a 9.5:1 piston though... there site does not specifically call out the SE heads. Would you recommend another cam selection?

Last edited by wickedevo; 03-06-2010 at 11:01 AM.

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