Did A Compression Test

[copper_gst]

I did a compression test yesterday and this is what I found. I still have boost leaks because the injectors aren't seating right so I don't know if that would effect the test or not. I hope it would, but here are the numbers. The #1 cylinder 160 #3 cylinder 180 #2 cylinder 150 #4 cylinder 190. I Would appreciate all the help I could get on this, the car is also heating up still. I'm gonna put a new thermostat in it and see if that helps. Please let me know what you think.

thanks

curtis

[v8klla]

Well do the injectors go into the combustion chamber or into the intake manifold/head right before? If the injectors are in the combustion chamber that would adversely affect your numbers if they are leaking...

Chris

[AJ]

Might want to try a leak down test and try to narrow some things down.

[1ViciousGSX]

How many revolutions did you crank it over during each test? Wet or dry test? That is a pretty big difference between cylinders.

[SlowWhite]

time for MCCC?

-Brian

[john]

Was the car warned up when you did it? Two of the cylinders are too high (180 and 190). I believe the stock compression in a 2g cannot exceed 178 unless you have excessive carbon build-up or you did the test wrong. Retake the test after really beating on the car so you know it is warmed up. If the numbers are still high, clean your cumbustion chambers with MCCC like Brian said.

[Raptor]

The higher compression isn't surprising, the head was milled >.010" and the valves are larger than stock, they are flat on the bottom instead of having the small dish like the factory valves. Both of those things will contribute to a little higher compression numbers. The leakdown test like allan mentioned is really the next thing to do to see where the varience in coming from.

Injector seals don't cause compression leaks, they are inside the intake runner and behind the valve so they have no effect on compression. They can leak boost like you found of course.

The last thing is to obviously make sure you are using an accurate compression tester. Lately we have seen some really bad numbers come from cars that were fine due to people using junk testers. Use an equal number of revolutins, throttle blade open etc.

[Shane@DBPerformance]

Isn't it 9.0:1 compression also?

The car was acting like some other cars that we have dynoed that had blown headgaskets. They have ok compression and can run all day under normal driving conditions, but as soon as you put a lot of boost to it the coolant temps start skyrocketing.

[john]

Originally posted by Raptor@Apr 30 2004, 11:51 AM
The last thing is to obviously make sure you are using an accurate compression tester. Lately we have seen some really bad numbers come from cars that were fine due to people using junk testers. Use an equal number of revolutins, throttle blade open etc.
Mine is fine. We checked it on ghettostyle's car. Iceman just doesn't know how to use one :stick: .

[copper_gst]

yeah, it's 9.0:1 The car was warmed up, but I'll get another tester and do it again. I've never done a leakdown test either so some info on that might be helpful. I'm going to fix the injectors either tomarrow or on my day off. I'll keep you posted. Thanks for the help, any more is greatly appreciated.