sr20det compression question - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

jacko_ · 11-08-2012, 11:09 PM

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 · 11-09-2012, 12:34 AM

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

Sent from my HTC Desire HD using Tapatalk 2

Kingtal0n · 11-10-2012, 08:18 PM

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

jacko_ · 11-13-2012, 04:14 PM

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 · 11-13-2012, 07:35 PM

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

n33sanz · 11-13-2012, 08:45 PM

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

*fliprayzin240sx* · 11-14-2012, 04:18 PM

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.

11-08-2012, 11:09 PM	#1
jacko_ Join Date: Nov 2012 Location: australia Age: 31 Posts: 4 Trader Rating: (0) Feedback Score: 0 reviews	sr20det compression question 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.

11-10-2012, 08:18 PM	#3
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 38 Posts: 4,649 Trader Rating: (17) Feedback Score: 17 reviews	if the engine has cams, carbon buildup, or worn out pistons rings... those are fairly common excuses for a low compression test. __________________ 5.3/4l80e/turbo 240sx playthrough: https://tinyurl.com/turbo240

11-13-2012, 07:35 PM	#5
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,056 Trader Rating: (34) Feedback Score: 34 reviews	If you added oil (wet) and it jumped up to 140, your rings are shot and you need a re-ring... __________________ My SR20VET

11-14-2012, 04:18 PM	#7
fliprayzin240sx Man w/ CTSV & a Car Seat Join Date: Aug 2002 Location: Tampa Posts: 17,998 Trader Rating: (19) Rides Gallery: fliprayzin240sx Feedback Score: 19 reviews	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. __________________ If you think Zilvia has too many assholes... CLICK HERE!!!

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11-09-2012, 12:34 AM	#2
liamc111 Join Date: May 2010 Location: essex, UK Age: 31 Posts: 4 Trader Rating: (0) Feedback Score: 0 reviews	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 Sent from my HTC Desire HD using Tapatalk 2

11-13-2012, 04:14 PM	#4
jacko_ Join Date: Nov 2012 Location: australia Age: 31 Posts: 4 Trader Rating: (0) Feedback Score: 0 reviews	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.

11-13-2012, 08:45 PM	#6
n33sanz Leaky Injector Join Date: Oct 2011 Location: CT Posts: 107 Trader Rating: (2) Feedback Score: 2 reviews	Despite that being low at least it is consistent. If the engine is running fine why are you concerned?