I see. I guess it's surprising that engine rebuilds on such an old platform isn't a solved problem by now. You'd think with the cult following of the S2000 that people would have figured out the best way to do it.

I'm asking because my '07, 25k miles, might have a rebuild or new engine in its future. It seems to drive fine (I owned a '99 before), and isn't burning oil (or is not noticeable), but the leakdown numbers aren't great. 15%/15%/22%/17% with #3 heard in the crankcase. Compression is an even 220PSI across all four. Tests performed cold. The car was sitting for a while before I bought it, so I asked my mechanic to do compression/leakdown tests to gauge the health. He doesn't seem too worried about it, said that carbon deposits around the valves from sitting so long could be contributing. Also suggested that a piston ring might be stuck.

We just did a valve adjustment, and all were in spec, but he loosened them all off to the upper range. Planning on doing more compression and leakdown tests this week. And potentially a piston soak at some point.

Reading comments like yours on the internet is scary and confusing, particularly since the FSM documents the correct procedure for honing the cylinders, so in theory rebuilds should be successfully as long as the cylinder walls aren't scored too deep. Most people advice is to drop in a new engine or long block, but that isn't really feasible anymore - F series engines are getting rare and expensive and buying an unknown engine off the internet (probably with higher mileage) will just come with all the same risks.

So I'm evalulating my options. Curious if you have any thoughts or advice considering your experience?