BAR7MAN

I have a 91 redtop sr20det with a little under 81k miles and decided to compression test it last night before getting ready to install a new turbo (gt2871r) and supporting mods. Motor is bone stock (as far as I know) aside from basic bolt ons...exhaust, fmic, intake.

I did this on a warm motor, with the throttle wide open, and all the plugs out. This was done at 5600' elevation so I believe these numbers are about 15% lower than if I were to do it at sea level. Here are the results:

Dry: 110 105 113 115
Wet: 130 127 135 144

Are my rings toast? Do I need a bottom end rebuild?

If so, what are your suggestions? My plans are just for a gt2871r .64ar, ewg, s3 cams to get around 375-400hp. I have no plans to go any further than this in terms of power. I don't drift or daily drive the car.

Thanks

di-devol

Well, if I did this right, here are the corrected numbers:

correctedNumbers
# Result: [126.17, 120.435, 129.611, 131.905] #

This is based on a .853 correction factor, which I found in some [email protected]'
I dunno, I could be wrong, I jsut got to work haha.

Still seems pretty low, but you can't tell whats causing the issue for sure unless you do a leak down test.

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harlockssx

You're right at ~9% variation between your cylinders average, so I think you're fine, as long as it's running well and there's not excessive oil blowby and consumption. More than that is usually indicative of some problems.

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Old School

BAR7MAN

Yeah I plan on doing a leak down test sometime within the next week or so hopefully to see if I can determine what's going on.


Car is running mint! I only decided to do the compression test out of curiosity before upping the horsepower. No oil consumption issues either.

TheRealSy90

If it runs fine that it's fine and I would leave it be. It may seem lower than usual, but they are all close enough that it still runs healthily. Especially after you do your turbo, gate, and cams that will help give it a nice kick in the rump. Remember you'll want larger injectors and a tune to go with it!

You're more likely to have issues after trying to rebuild the bottom end then just leaving it be for now.

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BAR7MAN

Cool deal, I definitely don't want to rebuild it if it's not entirely necessary. And yep, injectors and pump are on the list of stuff I still need! Along with a tune for sure!