A little clarification to whether or not you can use factory bores (since I seem to be the only one with forged pistons and stock bores). Its really quite simple: Measure the bores just like you would after boring a block (you may find the stock bore just as straight as a bored block). If the stock bores are within spec in regards to taper (if bore size is out of spec you've really f*ck up beyond discussion) it can be reused. I had 65K and nitrous with not a thing wrong with my bores. As far as piston to bore clearances they are set by the piston maker, doesn't matter if you bore or not. JE recommends .003", Ross .004". Most high strength forged pistons run anywhere from .003-.009 (hence there is no such thing as a tight fitting high strength forged piston). I say high strengh because there are basically two types of forged pistons you'll want to deal with. 2816 low silicon aluminum described above and 4032 high silicon pistons (JE's SRP, Ross sportsman, Arias off the shelf ect). These pistons run tighter clearances due to the high silicon (and less expansion) but are more prone to cracking (although probably stronger than what you'll ever throw at them).
If your bore is straight and measures x. you give piston maker x and they make the pistons to whatever clearance your heart desires. I foolishly didn't listen as if I were building a 700hp monster (went with .005" instead of .004" although they said it would be okay too) and now have to put up with a noisy when cold engine but the likely hood of blowing your engine due to piston to bore clearance issues is mute to none. And if you listen to the manufacturer you probably wont deal with as much noise (I still cant see a piston with .003" clearance being perfectly quiet). If you buy off the shelf pistons you have to do whatever is required but if you order them custom you can get what you need. I paid $425 including pins, locks and shipping and have a print out of each pistons weight, bore diameter in three places on the piston, piston crown thickeness ect ect. Another $100 bucks for total seal rings (well I paid $150 but oh well). Its been running for a year now and with nitrous so until it blows (there's always tommorow) I cant not recommend using factory bores. One thing I dont understand though. If your gonna replace all your pistons, boring is only $100 if not less so where is the great money savings? Do you plan on not pulling the engine or something? I didn't bore cause people said you couldn't(So much for listening to everything you hear). If you have excessive blowby and an excessively noisy engine it will be from not setting proper clearance and confirming straight bores not from using the stock bores.


Stan2gnt
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95 Talon ES-I-NOS
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