RB26 Compression Test

[caminperth]

Hi all,

I'm thinking about buying an RB26. The compression has been tested by a reputable shop and came out an average of 125 psi, with a deviation of 2 psi either way.

Looking in the Nissan RB26 manual, it says that new it should be 171 psi and the lower limit should be 128 psi with a deviation of 14 psi.

The shop who tested it seemed to think that as the values were consistant and the engine runs well and makes good power (400 rwhp - not stock turbos) that it either has forged pistons or a thicker head gasket.

Opinions? Ideas?

Cheers,

Cam

[rep003]

tough call big guy ,

short of actually removing the head ( my personal prefference ) ,

you could look for signs of a rebuild , new gaskets , belts , pumps etc?....the sump seal is an easy 1 to spot , it's all gasket goo..grey is origonal & orange is replacement ( not always , but both are nissan goo just the grey one is much more $Bling$ )

Good luck

[Oosh]

Seems a bit on the low side...

[Sydneykid]

Hi all,

I'm thinking about buying an RB26. The compression has been tested by a reputable shop and came out an average of 125 psi, with a deviation of 2 psi either way.

Looking in the Nissan RB26 manual, it says that new it should be 171 psi and the lower limit should be 128 psi with a deviation of 14 psi.

The shop who tested it seemed to think that as the values were consistant and the engine runs well and makes good power (400 rwhp - not stock turbos) that it either has forged pistons or a thicker head gasket.

Opinions? Ideas?

Cheers,

Cam

Get them to do a leak down test, that will give a much better indication of engine condition, a compression test has too many variables.

[caminperth]

Rep - I'll have a closer look at those things next time I check it out..

SK - Agreed. I'm guessing a leak down will tell me if there is a problem - no leaking therefore the compression is ok.

Cheers,

Cam

[fsmout]

hey man, when i bought my r32 gtr it was really obvious that one of the cylinders was down, they were all at 150psi except for 1 that was at 90psi...when we pulled the engine down that one cylinder was F*&^%%ked but the others were fine?

Cheers,

Frank

[caminperth]

fsmount - thats what I'm thinking, all the compression readings taken are consistent so hopefully they're all ok..

[itbmils]

Not necessarily guys

I also have a R32 GTR (doesn't everyone) - when I did a compression test it was a steady ~150psi across the block (+/- 5psi) - but a leak down test told a VERY different story (pots 4 and 6 were shot). Pot 6 always goes first – and points to low fuel pressure apparently (some fault with the plenum design??)

I saw the pistons and the bore once it was striped down – and they were in very bad shape (now running 1 size over)

BUT

She also ran fine (even @ idle) and running 15psi she pushed out 210awkw with R32 N1 turbos. Not bad with only 4 pistons – and everything else standard.

Only reason I found out was that I wanted to do some more mods – and get a LITTLE more power – so I started with a full check over of the engine. Ended up pulling the head off just to make sure – and things went down hill from there.

A FULL rebuild fixed the problem ($10K latter)

Now pulling 280+awkw

[fsmout]

sounds like the leak down test might be a good idea.

itbmils - are you still running the r32 N1 turbo's making the 280kw@w?

[caminperth]

Definitely sounds like I'll be doing a leakdown test...

[itbmils]

fsmount - no I now have R34 N1s - sold the R32 ones already