Yes, everybody, I know this means there is something wrong, that it's not supposed to lose horsepower with raised compression.
One thing that occurred to me is that if the head warped, maybe the valve seats don't seal perfectly. But the compression test showed 150-170 PSI on all cylinders after it was reassembled, so I don't think that can be it. There's also the question of cam timing, which might be off a bit or might not be. What I can say is that in the last year or so, the intake and exhaust cams have somehow diverged a bit so that they are out of sync with each other by about one degree. But neither seems to be off by more than maybe a degree and a half overall, which is about as accurately as I can measure it anyway.
Originally posted by JonsZX2SR:
What year is the car and what fuel are you running? It is possible that the knock sensor has detected some pre-ignition and pulled advance out of the ignition curve.
I don't think I have a knock sensor. I'm using 91 or 92 octane, since I got definite pinging on warm days with 89 and terrible pinging with 87. It might still occasionally ping just a tiny bit on the first moment of pull from a stop, but it's so brief and faint I can't tell if it's actually pinging or not.
It sure would be nice to hook up some good diagnostics and find out what's going on with the timing, mixture, etc. 
