ISFFUN

iTrader: (4)

Hello,

Ran a compression test with the engine hot and all other plugs still in socket.

150K miles

All cylinders were in the 65-70 range, no large differences between them.

Head gasket is new and no oil burning/smoke.

Dyno showed about a 10HP loss from original specs (dyno 210 vs 220) using 18% estimation of drivetrain loss.

Any ideas?

stockhatch

iTrader: (12)

Are you positive your gauge is working properly? With numbers that low, the car would not want to run well, much less make only 10hp less than the last dyno. I'm sure you know that dyno numbers can vary greatly depending on the shop, the weather, conversion factors, altitude, etc. If the car seems to run well and does not miss at idle or smoke, I don't see how your compression numbers can be accurate. Did you try to put a few drops of oil in the cylinders and see if the numbers come up? Have you done a leakdown test?

stockhatch

iTrader: (12)

Also, run your test without the plugs in. The engine will turn over faster, and you eliminate false readings in the event that there are leaks between the cylinders.