sr20det compression question

[jacko_]

Hey all.

I have a 2002 s15 with a sr20det that I have owned for about 8 months. I don't have any information on the engines history other that the odometer saying 190,000ks. It does have an upgraded garrett turbo that seems larger than the standard t28 and a high mount manifold with aftermarket oil lines. The car is also running fmic and 3" exhaust with a switch to alternate between 11 and 15psi.

I recently had the compression tested at a few workshops and results were
105,105,105,110. the tests were done with the throttle body open and warm.

The car still goes very hard and is not using any noticeable amount of oil. Has anyone come across a build situation where this low pressure would be deliberately done (thicker head gasket, different pistons)? Or is it simply engine deterioration?

Any ideas would be appreciated, I'm hoping I don't have a rebuild situation on my hands.

[liamc111]

Standard compression should be between 150psi (brand new engine)
And 125psi iirc.

Have you done a wet compression test to see if its worn rings? Also do a leakdown test to see if its leaking past the valves.

Only way I think of seeing if their aftermarket pistons without stripping the engine down is to get a bore scope in there and have a look at the piston crowns

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[Kingtal0n]

if the engine has cams, carbon buildup, or worn out pistons rings... those are fairly common excuses for a low compression test.

[jacko_]

thanks guys.
I took the car to an engine shop to get another compression test (dry and wet) and a leak down.

The results came back 140 across all 4 and 20% leak. So far better results that the others.Very relieving, Hopefully the engine has a long life ahead of it.

cheers for your time.

[jr_ss]

If you added oil (wet) and it jumped up to 140, your rings are shot and you need a re-ring...

[n33sanz]

Despite that being low at least it is consistent. If the engine is running fine why are you concerned?

[fliprayzin240sx]

Well, he took it to shop to get checked and they got 140 so I'd be able to sleep at night with those numbers. 20% leak down tho is kinda sucky. I'd just drive that till it blows and have another block to rebuild when the day comes.