Compression test #s?

Wiggles422

Member
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MSP #654
I'm going to borrow a compression tester from a friend before I decide to up the boost. I figured it would be a good piece of information to have so I can check every so often just to be on the safe side. Anyways I'm sure someone else has done this... what numbers are to be expected? I'm guessing 190ish (shrug)
 
don't know the numbers off hand,but just make sure they are about the same for each cylinder
 
it should be around 190-200. from i remember when maurice did his first test it came out around 185. but he had been boostin high for a while.
 
can someone tell me whether or not the proper procedure is to do the compression test with the throttle open or closed. I thought it was supposed to be open but my friend said no, and we did it his way. I ended up getting between 135-138 on all four. Ive been upped on boost for awhile and this was done awhile back, cars still fast and runs well. Im thinking it had something to do with that.
 
i dont mess with the throttle, also did you remove the fuel inj fuse? the manual said to do it.
 
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throttle should be open. Those numbers are slightly low, still within specs. Could just mean you didnt get a "good" motor like me. lol
 
throttle open or closed shouldnt make that big of a difference, ive done it both ways on all my jeeps and cars and it was always close on the #s....pull the fuse turnover four times and read the gauge...if you want to test if a ring is going or if you think the #s are low add a capfull of oil down each cylinder and do the test again...if the compression jumps up by more than 10psi then you have a blowby issue...
 
DSMConvert said:
throttle open or closed shouldnt make that big of a difference, ive done it both ways on all my jeeps and cars and it was always close on the #s....pull the fuse turnover four times and read the gauge...if you want to test if a ring is going or if you think the #s are low add a capfull of oil down each cylinder and do the test again...if the compression jumps up by more than 10psi then you have a blowby issue...

good info :)
 
I went to Autozone to rent a compression tester and they didn't rent them. So I went to PepBoys, they didnt have one in stock. Does anyone know of any other places that rents tools? (for free) I think I might just order one online, they're fairly cheap.
 
autozone doesn't useally rent tools what they do is sell you the tool and when your done you return it for a refund.
 
DSMConvert said:
throttle open or closed shouldnt make that big of a difference, ive done it both ways on all my jeeps and cars and it was always close on the #s....pull the fuse turnover four times and read the gauge...if you want to test if a ring is going or if you think the #s are low add a capfull of oil down each cylinder and do the test again...if the compression jumps up by more than 10psi then you have a blowby issue...
Never heard that, where did you hear this?

Anyway, my compression #s on my stock motor were 175ish, but then when I did them again with the injector fuse pulled, they were 140ish. Ditto for my new motor.
 
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