Compression test confusion! Really good numbers or innacurate test? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

SilviaSalvia · 05-09-2013, 12:03 AM

I bought a SR20DET redtop from jdm engine depot about a month ago. Warranty is up in a couple days so I want to be sure the engine is good before that comes up.

Put a little bit of oil in each cylinder to keep the pistons from dry rubbing against the walls since the engine has been sitting for such a long time before it even got to the U.S. Tried compression test when I got it but starter went bad so I finally got a new one. 1 month later I try the compression test again. Didn't add any oil this time.

1st (Farthest away from transmission) - 150
2nd- 150
3rd- 150
4th - 165

I looked up a bunch of compression tests and I can't figure out if this is good or not. Should be even across the board if its nice and healthy but why the hell is the last one 15 higher? Is that a good thing?

BTW if this wasn't obvious already, this is a completely cold as cold can be compression test. Apparently once the engine is warm, the numbers should shoot up about 10psi(?)

ALSO to note, I've been using an old battery that's been sitting around from when I had my single cam. Not sure if that effects anything.

Not done with the throttle open.

Each cylinder got a good amount of cranks before I stopped.

05-09-2013, 12:03 AM	#1
SilviaSalvia Leaky Injector Join Date: Jun 2010 Location: Nassau, Long island, NY Posts: 85 Trader Rating: (0) Feedback Score: 0 reviews	Compression test confusion! Really good numbers or innacurate test? I bought a SR20DET redtop from jdm engine depot about a month ago. Warranty is up in a couple days so I want to be sure the engine is good before that comes up. Put a little bit of oil in each cylinder to keep the pistons from dry rubbing against the walls since the engine has been sitting for such a long time before it even got to the U.S. Tried compression test when I got it but starter went bad so I finally got a new one. 1 month later I try the compression test again. Didn't add any oil this time. 1st (Farthest away from transmission) - 150 2nd- 150 3rd- 150 4th - 165 I looked up a bunch of compression tests and I can't figure out if this is good or not. Should be even across the board if its nice and healthy but why the hell is the last one 15 higher? Is that a good thing? BTW if this wasn't obvious already, this is a completely cold as cold can be compression test. Apparently once the engine is warm, the numbers should shoot up about 10psi(?) ALSO to note, I've been using an old battery that's been sitting around from when I had my single cam. Not sure if that effects anything. Not done with the throttle open. Each cylinder got a good amount of cranks before I stopped.