nate-b16turbo

Running a b16a2 in an ej6 coupe with wiseco 9.0:1 pistons w/eagles rods, stock crank, stock vavles, skunk 2 dual valve springs, titanium retainers, edlebrock victor x, aem fuel rail w/rc 270cc injectors, currently no operating system(ecu is only chipped). Was gonna run this setup with a turbo but decided to go naturally aspirated for the time being.

Compression Test:
-Dry Test-
Cylinder 4:140psi
Cylinder 3:145psi
Cylinder 2:120psi
Cylinder 1:145psi
-Wet Test-
(I squirted some Marvel Mystery Oil in the cylinders)
Cylinder 4:145psi
Cylinder 3:150psi
Cylinder 2:145psi
Cylinder 1:145psi

Leak Down Test:
Cylinder 4:15psi
Cylinder 3:20psi
Cylinder 2:15psi
Cylinder 1:20psi

I'm not positive what these results mean, I know that the compression in each cylinder is supposed to be 185psi when the motors new and is not supposed to be over 28psi apart. Do the pistons I have now lower the compression of each cylinder?

I've read that when doing a leak down test, that any reading over 10psi is when you need to start worrying about too much compression loss.

Any help on these topics would be much appreciated!
Thanks in advance.

86azms3

When you lower the compression of your motor, your compression numbers will read lower.

I would say there is some issue going on with cylinder 2.

blackeg

was the motor at operating temperature and the throttle wide open when you did the compression test?

even with 9:1 compression, you should see at least 170-180 psi. did you find where the leakdown was going? out of the intake? exhaust? bubbling the coolant in the radiator? past the rings (the hissing will change pitch when you take out the dipstick or oil fill cap)

91integraLSVTEC

doesnt seem like you did the cylinder leakage test correctly. Give us an update when you find out

TomCat39

Also can you provide the details of how you did the compression test?

There is so many different ways people do the compression test that provide different results. The key being you do the same process on all 4 cylinders.

Saying you should see 170 psi may not be accurate if your procedure is to only have the motor crank 4 times with WOT and a warm engine.

Like wise, saying you shouldn't see more than 185 psi WOT with engine warm may not be accurate if you crank the motor until the needle stops.

The exact details of how you do these tests can significantly impact the final numbers you see.

Typically the crucial part of the compression test is the variance between cylinders when you do all 4 the exact same way, not the psi numbers themselves as that changes with the method used to do the test (4 cranks versus 8 cranks versus needle stops).