OK, so here is what I've got, my girl friends circle track car HAD a rebuilt D16Z6 engine, I built at the beginning of the season. Well the engine lasted just that, ONE season, last race, they threw the checkers and a rod went through the block. SO I now have a winter project!!! OK so I've got a D15B sitting on the floor of my shop, I know NOTHING about the engine, its been sitting for 2 years, I plan to tear into it and rebuild it. NOW, my track rules say we have to keep these engines built with OEM parts, no aftermarket B.S. so I have to be careful. What I'm looking into is, will I be better of rebuilding another D16Z6 or the D15B I have? I know the D15B has a different stroke, but everything else seems pretty equal. We run a stock P28 ecu, and we can't chip it. Also, I'm looking for an ANSWER to this quesiton: I've read up on the D15B3 Carb'd Engine. 9.9-1 CR????? Can I use these pistons in either the D15B or D16Z6 if I can find some? Will it hurt or help?? Thanks in advanced!