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'83 280ZX Turbo Compression Numbers


ZLadie2000

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Well I finally did a dry and wet compression test on this car. Had noticed some oil on my spark plugs and suspected the piston rings.Here are the numbers.

 

 

Cylinder 1: 120 psi / Wet 160 psi

Cylinder 2: 120 psi / Wet 170 psi

Cylinder 3: 130 psi / Wet 150 psi

Cylinder 4: 120 psi / Wet 145 psi

Cylinder 5: 130 psi / Wet 163 psi

Cylinder 6: 135 psi / Wet 173 psi

 

 

Not bad for a 26 yr old Turbo engine. The minimum should be 100 psi, Normal is 140 psi.

 

 

Looks like I have a Piston Ring problem though, right?

 

 

I'm going to just replace the Piston rings, Head Gasket, and Valve Guide Seals/Stems all at once.

 

 

Since I want to put a T3/T04E .50 Trim, .63 a/r turbo on there, Intercooler, 3inch exhaust and turn up the boost.

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Guest Rolling Parts

Looks like I have a Piston Ring problem though, right?

 

Not really. Of course there is wear but theses engines will go 300,000-400,000miles. Unless there is a real want to dissemble the engine

you don't really need to based on those numbers.

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I don't know the Orlando area well enough to recommend anyone. Try to find some other Z car drivers there and ask around. Most every major metro area has a Z specialty shop that is typically run by a retired Nissan dealer tech that does good work. Occasionally you can luck up and find a tech still at a dealer that has older Z car experience and does quality work, but we are getting more rare as so many dealerships these days are pushing profit over quality/experienced employees. If you've only done minor maintenance I would not suggest a rebuild as your first internal work.

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I once did a ring job on my L28 while it was in the car. At that time i didn't have an engine hoist so thought I was saving money. You can do it, but it's awkward and a bit back breaking leaning over the fender to break the glaze on the cylinders. Given that Harbor Freight often has hoists for about $100, I'd suggest you get one and pull the motor. The extra time spent is easily offset by how much easier it is to reassemble it on an engine stand. Plus you'll be surprise how many more times you'll use the hoist, especially if you make it habit of hanging around here :)

 

BTW, except for the compression test and oily plugs, are you experiencing any other issues with the engine? How much oil does it burn in 1000 miles? Just suggesting that you might not want to bother until you're ready to do a proper rebuild. In my case, less than 10k miles later that's what I was doing.

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BTW, except for the compression test and oily plugs, are you experiencing any other issues with the engine? How much oil does it burn in 1000 miles? Just suggesting that you might not want to bother until you're ready to do a proper rebuild. In my case, less than 10k miles later that's what I was doing.

 

 

It doesn't burn oil. I have major idle issues and hesitation/lack of power randomly issues, I see these issues especially when cold. The high idle (1000rpm) is persistent though. What I hate the most is that it will randomly loose power...especially in lower rpms from 1st to 2nd etc. I think there may be some misfiring going on due to the oily plugs...(not getting good spark, etc). So that's why I want to replace the piston rings, etc.

 

My turbo is pretty strong but showing signs it needs to be replaced. It seems like it only maxes out at about 4.5 - 5psi or so. (based on my gauge, it doesn't go into the red anymore). So I will replace the turbo with the t3/t4 setup, but before I turn up the boost and start really having fun with the car I want to make sure the engine is good, rings are replaced and head gasket, etc.

 

See, it's all a chain effect!

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Hmmm, you say you're not burning any oil - then I'd challenge that the oily spark plugs and low compression numbers are due to worn rings. I'd be looking at the valve guides and seals as you mentioned instead.

 

You might want to rebuild the bottom end while you're at it, but I don't think that is the root cause of the issues you describe.

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