R32 Gtr Cylinder Compression Values

[PhilGTR]

Hi Guys,

Im planning to buy an 1990 r32 GTR. and I am having the engine compression tested. But im not sure what the values should be in PSI. Can someone please help? Thanks in advance!

[Abo Bob]

There has been a couple of threads on this in the last few weeks.

A leak down test is more informative than a compression test.

Also, it's more important that the compression is even than that it is a particular psi on a particular gaugue on a particular day with a particular battery level with whatever temperature the engine is.

All of those things affect the reading.

[PhilGTR]

Thanks for your reply, i got the results in and the compression in each cyclinder is as follows: 90 75 90 75 90 90. The guys at the workshop reckon this is okay. But like you said its pretty even. So should this be a worry at all?

There has been a couple of threads on this in the last few weeks.

A leak down test is more informative than a compression test.

Also, it's more important that the compression is even than that it is a particular psi on a particular gaugue on a particular day with a particular battery level with whatever temperature the engine is.

All of those things affect the reading.

<{POST_SNAPBACK}>

[Amaru]

Thanks for your reply, i got the results in and the compression in each cyclinder is as follows: 90 75 90 75 90 90. The guys at the workshop reckon this is okay. But like you said its pretty even. So should this be a worry at all?

<{POST_SNAPBACK}>

If the compression test was conducted properly (warm engine, wide open throttle when cranking) then those results are pretty poor and the engine is fairly worn out. I believe Nissan specifications say 130 - 170psi.

[PhilGTR]

WHat do you mean by wide open throttle when cranking? This GTR also has a worn out clutch would that affect the reults at all?

If the compression test was conducted properly (warm engine, wide open throttle when cranking) then those results are pretty poor and the engine is fairly worn out. I believe Nissan specifications say 130 - 170psi.

<{POST_SNAPBACK}>

[Amaru]

The throttle should be 100% open when performing the test (e.g. someone pushing the accelerator to the floor when cranking it)

[Beer Baron]

worn clutch will not affect the reading.

[Abo Bob]

Sounds like the engine was cold when it was done too.

The numbers aren't too important. I don't think those numbers are even enough.

Anyone else agree?

[whitesky]

they sound a bit low to me. My R32 GTR is 150 150 150 145 150 160. Original engine from what i can see, reading 70k on the clock, but probably more in reality.

[PhilGTR]

Ok so maybe I shouldnt buy this one then. So if its cold when it is being done it can affect it? I might check that. Thanks for your help guys.

[Abo Bob]

I think the readings are all lower if the engine is cold but it shouldn't affect the evenness of it.

[Beer Baron]

maximum acceptable variation generally is 14psi.

[GTRsean]

Engine should be adequately warmed, fuel pump fuse taken out, throttle floored and crank engine until gauge doesn't move. 8 or so compression strokes.

from nissan manual

new 171psi

normal 160psi

limit 128psi

14psi max variance between cylinders.

I tested mine and got 175 175 175 165 170 173psi, 1992 GTR

It was higher than stock? Could it be from carbon in the cylinders increasing the compression ratio?

[Aztec]

the gtr you're looking at might have a metal head gasket, one possible reason for the low compression, my manual said you should get a reading of 170psi.

[RellikZephyr]

when i got mine tested 1990 GTR

i got 140 140 135 140 135 140

which is ok for one thats done 100k little low but even so...

and as far as i understand u dont wanna go below 130

i dont know the whole deal but those pressures dont sound good

good luck

RellikZephyr

[GTR032]

I just had mine comp tested at Grey imports here in sydney. 190 highest and 180 lowest..maybe gauge was reading high? But still pretty even which is a good sign, nathan there said, no need for a leak down test, its pretty good.

[The Dan]

after I rebuilt my gtst - which is practically the same so be quiet all you GTR owners - I had a reading of 120 140 130 160 80 120 when it was cold and a reading of 160 160 160 160 160 160 when it was warm.

This is how much of a difference it will make so get it checked when it is at operating temp.

I also have forged pistons so be quiet all you cast piston owners....lol