Urgent Help

[wes81]

Hey guys im just about to put a deposit down on a skyline...

i just had it tested and everything is good..

the compression test came back 120 for each cylinder..

Any opinions... is 120 ok or not acceptable at all.

[r33_racer]

nooooooooope. Might be good if you wanna screw them for price by a grand and then rebuild it. Depending on motor/condition it should be around 160-170.

[wes81]

Mate thanks for that im so confused. I have read that we should not accept anything under 130..

After speaking to the mechanic and then another mechanic. they both told me that because it is a turbo engine they have a low compression..

[r33_racer]

yeh compression ratio is low...but cylinder compression is different to your CR. They are probably relative to eachother, but most RB's should be around those figures. But most std ones that have been around or thrashed will more then likely have low compression....rings are shagged

[Sydneykid]

Hey guys im just about to put a deposit down on a skyline...

i just had it tested and everything is good..

the compression test came back 120 for each cylinder..

Any opinions... is 120 ok or not acceptable at all.

What model?

150-160 is OK for R33GTST (RB25DET)

130-140 is OK for R32GTST (RB20DET)

Compression tests are a bit unreliable for absolute numbers, depends if the engine is properly warmed up, how good the battery is etc. Compression test is really only good for picking one (or two) cylinders being down on the rest. Leak down tests (wet and dry) are a more accurate check.

cheers

[wes81]

its a 95 rb25det

i just spoke to simon at promaz in vic and he said 120 is fine

[r33_racer]

thats low....maybe not in someone elses books but in mine it is. A cold test i would want it to be around 150-160 no less then that or your in for hard starts and poor economy and lack of power and lots of blow by...eventually.

[wes81]

should also add that it is stock as a rock only exhaust.. and it has 106K on the clock

[R31Nismoid]

Your talking to a Rotor specialist about an RB?

[wes81]

yeah i know....just spoke to Nismo car centre and they said 120 is way to low

i might give this one a miss. Thanks for the help guys

[wes81]

just got the report back from the Mechanic. After speaking to the guy at Nismo he said that it depends how the guy did the test. was it cold or warm was the battery good. But this is what it got.

1. 120

2. 120

3. 120

4. 120

5. 120

6. 120

just reading through all the hundred of compression threads it still up in the air. Some say as long as the number is even across all cylinders its ok.

thanks again for the help

[RANDY]

Can anyone advise if that's a little TOO even? A perfect 120 on all cylinders?

[assyrian4evaa]

Compression tests are a bit unreliable for absolute numbers, depends if the engine is properly warmed up, how good the battery is etc. Compression test is really only good for picking one (or two) cylinders being down on the rest. Leak down tests (wet and dry) are a more accurate check.

bro i've gota ask you about this LEAK DOWN TEST wat exacty is it?

Can anyone advise if that's a little TOO even? A perfect 120 on all cylinders?

i was thinking the same thing that is abit too even ey

[700HP-GTR33]

just got the report back from the Mechanic. After speaking to the guy at Nismo he said that it depends how the guy did the test. was it cold or warm was the battery good. But this is what it got.

1. 120

2. 120

3. 120

4. 120

5. 120

6. 120

just reading through all the hundred of compression threads it still up in the air. Some say as long as the number is even across all cylinders its ok.

thanks again for the help

Have you driven it yet?

It sure looks suspicious all to be that spot on.

I was wondering if work load such as pulling or carting things around could have a greater even load

on the way the cylinders wear, lots of high constant speed could do this aswell i would think.

This may explain the results if they are correct.

If a car has been thrashed , usually there are particular stress caused on some cylinders and wear

and compression are uneven.

Check out to see if those km's are genuine. then look for wear on the boots etc.

Offer them $2000 less and have the thing rebuilt if you are concerned.

If the car is clean and looks like it has been taken care of ,test drive it ,get it checked once over and if you are happy , buy it.

[r33_racer]

I would say there is probably variation between those figures, but the mechanic that did it, probably ignored the 0-10 figures and rounded the buggers up or down to 120 to call it even.

[wes81]

Thanks again for all the info. I had another look at it to day and it is clean couldnt see any oil any where and the engine bay looks good.

Couldnt take it for a test drive today cause he was the only one in the office.

I got the car VACC tested. They said the only thing wrong with it is that it needs the radiator flushed and thats all other wise they gave the car a good rating..

Again guys thanks for the help. Sorry to clog up the forum with more compression posts.

Will keep you posted if i bu it or not

[FSTR32]

Yeh i agree...sounds a little too suss to have 120 across ALL cylinders and yes i belive this is very low. Again like Nismo said it will depend on the conditions the test was done (wam/cold)

I did comp and leak down test on my old neo rb25 (cold) and got these figures

1)120

2)165

3)160

4)155

5)150

6)155

Pulled apart engine and piston 1 was FRIED as a mofo ------> SEE PICS BELOW

I would be VERY careful. Could turn out to be a lemon and cost you big.

My 2 Cents

Edited August 26, 2006 by FSTR32