Hi everyone. I did a compression test today on my 91 NA Z32 and I got a reading of 145 - 155 on all the cylinders. So that should be decent right?
Also I read I was suppose to do the test with WOT
but I just cranked the engine without opening the throttle.
Twinturbo.net said that WOT would have a slightly higher compression reading.
Is that true?
would that mean if I did do it with WOT my readings would be a little higher?
should I do another compression test with WOT?

 

Compression should be around 180psi if I remember right.

Yes.

 

WOT isn't going to make that much of a difference - your engine isn't choking while cranking.

 

I've seen about a 5psi max on average rise between wot and not. So no big deal.

 

I did another compression test with wide open throttle and I got about 150 to 155 across all 6 cylinders. And no my engine doesnt choke while cranking. its has a nice constant crank to it. I think thats a pretty good reading. I was considering a rebuilt but since compression isnt bad I dont really need to huh?
thanks for all your responses.

 

... that's good compression for a Twin Turbo. For a non-turbo, you're 25-30psi low (as hoov said, it should be in the ballpark of 180). How is that a good reading?

 

Do you think I should consider rebuilding the engine?

 

Unless your gas mileage is in the *******, or it runs like crap I would just drive it.

 

What hoov said - just drive it. It is a non-turbo. Of course, you could replace it... with a twin turbo engine.

 

Gas mileage isnt great but its not bad either it is a Z
getting a new efi harness along with new injectors cause 3 crapped out. After that it should run great. No leaks or anything soo yeah not bad for 180k

 

I probaby get 300 miles a tank

 

And your complaining? ****, I can't get more then 270 out of my TT.

 

well thats true I always get somewhere around 280 to 300 full tank. Stock 270cc injectors

 

I promise your 270 twin-turbocharged miles are far more enjoyable than his 300 miles.

 

Got the JWT Pop Charger installed along with the new EFI Harness and 6 new injectors in and started my baby up and it ran like a champ. Quick response and acceleration. And this morning started it up again and smelled gas T.T... The #6 cylinder injector seal was leaking.... Now gotta take apart everything again and replace that ONE seal. Its gonna be a long *** day.

 

Its a 1990 NA with 93k miles (on the Odo, anyways). It wont start at all below 50*F, checked everything I could and decided to do a Cold compression test the other day on +26*F day and these are the results between Hot and Cold (PSI Readings)

-1 168 Hot - 65 Cold
-2 160 Hot - 45 Cold
-3 180 Hot - 65 Cold
-4 160 Hot - 55 Cold
-5 160 Hot - 40 Cold
-6 120 Hot - 30 Cold

Small wonder it wont start, I think a Cold Compression test can tell you dam near as much as a Hot test in the reverse aspect of things.
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Well, I finally got my JDM swap done and new EFI harness in and this car runs like a car should. I'm hoping I got a good one cuz I couldnt find anything wrong with it on the engine stand doing all the pre-install electrical and mechanical tests, hell, I even got 170 psi/cyl. using a 18" swing bar on the crank doing a poor mans compression test.........now to finish the TT.