I recently bought a project Del Sol, and had originally planned to pull and rebuild the engine(D16Z6), but I found a rebuilt D16Z6 engine with only 100 miles on it that was pulled out of a locals racing Del Sol. He felt it wasn't quite fast enough, and built up a DOHC for it instead.

My question is, will the stock tranny(5 speed) in my Si handle a Z6 that has double the HP of a stock Z6. I don't plan to hit the track or any other kind of racing, but I want to make sure my engine doesn't eat my transmission when I do decide to punch it.

 

So, double stock would be about 240-250 ish hp. I wouldn't think you would have any issue with that as long as the trans is in good condition and doesn't have any flaws to begin with. Of course as long as you're not beating on it or abusing the trans i myself wouldn't see any issues. Hopefully someone more knowledgeable will chime in.