low compression

[paul s]

Hey, I just checked my compression and it is even 150psi on each cylinder. A month ago it was 178psi. The car is boosted to 25psi daily and seems to drive OK. Do you think that it is the rings or bent valves, there is no abnormal noises. I usually shift at 7500rpm(HKS springs, 272/272). There is 16inches of vacuum at idle(1000rpm)...
Would the rings all lose compression so even? thanks Paul
I need to do some travelling this weekend and just wonder if I should take another car.

 

[CanadianTalon]

It's highly unlikely to bend valves or eat up rings so that all cylinders read the exact same compression numbers. I'd attirbute it to general variables (temperature, number of cranks, weather, etc), but if you're going on a road trip it wouldn't hurt to do a leakdown test.

 

[paul s]

I don't have the proper gauge to do the leak down test. I did someting like that, I took compressed air and put it in each cylinder and there was no leaks from the intake or exhaust manifold and if there was leak through the rings I could not hear it..??? I will try putting some oil in the chamber to see if compression goes up..One thing I didn't do was to hold the acc pedal down while cranking??

 

[Staytuned]

Go and change your battery. His car wouldn't crank over quick enough. With a boost he got 175 across the cylinders.