rb20 compression numbers

[doublejceballos]

So I went to test drive a gtst for sale on thursday. The guy has a vi done about six months ago when the police got him for headlights and exhaust
At that time he said TSS checked the compression (he's got papers) and they came out 1-121 2-130 3-130 4- 130 5-130 6- 130
I dont know too much about compression, but Ive seen many of you on here saying compression was great at 160 or 170 across the board
Does that mean this guys engine is running low?. He said TSS assured him they were great numbers.
Would an Rb20 run at a different compression than rb26?

Thanks for the help

[-Jay-]

Do a test yourself, its the only way of really knowing, not diffivult or time consuming to do either. You may be glad you did. I my first rb20 was about 130 in the middle 4 and 110 at cyl 1 and 6. Didn't have any problems but that is obviously a sign of wear somewhere.

[doublejceballos]

well I know the numbers are accurate, im just wondering if its a sign of engine problems...
Just to see what Im getting my self into...
I came across a thread very similar to mine on the search engine, but there are so many varied responses.
apart from the 1st cylinder, they are not too close to the manual's warning of 117psi

and if one was going to be lower, from what Ive been hearing is it not usually the 6th cylinder, not the 1st??

any info?

[-Jay-]

In my experience with rb engines (20/25) 1 and 6 have always been the lowest figures. I put that down to the bad flowing intakes manifolds.

[dm1133]

Those numbers seem fine, there's a problem with compression numbers if they are too varied, a bigger difference than +-15 in a cylinder from the others. However, it's also better if they're higher, but the numbers still seem good.

[BrianV8]

i heard rumor on the street once you get below 127 its rebuild time.

[doublejceballos]

Well I'm definately gettin mixed messages from everything I've been reading and on here. Some say rebuild is at 117psi? You'll have to remember this is a stock Gtst engine. I don't know. If I purchase I will be taking the car cross country in august and will be driving her hard. Am I going to have to worry about pushih it aka holding back and being worried about it. Or is there still quite a bit left in her?

[BrianV8]

oh you can keep her going, low compression numbers isn't something that will leave you stranded, i think 117 is a pretty much shot motor, yeah i wouldn't be concerned man, all low compression is is wear on your rings,

[doublejceballos]

so does any one know what kind of bills are involved in changing rings,
head, turbo, whole bunch of stuff has to come off,
Im not that mechanicaly inclined, so I would be going to a shop probably ztune

iz the 1st cylinder being that low not a major concern, any more info here guys?
THanks
p.s. dont tell me to "search" read them all

[BrianV8]

easiest way they will probably do it is pull the motor then yeah manifolds, head, turbo, everything comes off, i can see a pretty good size bill on that one.

[A18]

My car was compression tested by the previous owner on March 17, 2007 by TSS. The readings were: 130 120 120 130 130 130. I've owned it since June 2007 and I've never had a problem with it (knock on wood) that had anything to do with compression. It's a gtst with an rb20 by the way.

[DarkCaporaL]

Did you try checking the manual for the compression numbers?

If I remember, for the RB26, Nissan says new it should be like 180 and at 127 the engine is due for a rebuilt. I dunno about the RB20 though.

[dah_hunter]

I personally am Leary of anything below 130.. but thats just me..

[DeviantRebel442]

was it a cold test or warm test...

make sure it was a warm test because more often then not the cold test turns out LOW numbers...and they mean ****....

try the warm test and then you may get results which are better....

for the difference on my RB26 when i did it....cold test brought up 140....warm brought up 165....thats quite a difference

[nissan_for_life]

I just finished testing my compression in my Gts (RB20DET) and my compression is running 1-130 2-160 3-160 4-160 5-160 6-160. All the 160's are roughly that high, some were a little lower.