Jump to content
SAU Community

Recommended Posts

Lookin to buy a car and had a compression test done by performance place and just wondering if anyone can give me some advice. ill update the exact results for each cylinder later but on average no higher than 170 and no lower than 150, i think was somethin like 170, 170, 150, 160, 155, 150

like i said ill update bit later, but thats basically what i remember? was told its ok, then told its not any help please????

Thankyou!!

Link to comment
https://www.sau.com.au/forums/topic/247656-compression-results-on-34gtt/
Share on other sites

You get different readings depending on the battery and a few other components. I believe 150 is standard but the higher the better they say.

Of course they must be consistent with each other.

If there not identical to each other move on to another car until you find one that is.

You want it to be spot on

the other thing is you really need a leak down test also.

When i had my 100km service the compression was 170 170 170 170 60 65, since the car is pulling max power for the mods i was like wtf

Turns out i just had a heap of carbon build up in the intake.

Test after was 170 170 170 170 170 170

Ok results were As follows:

CYLINDER 1- 170PSI

CYLINDER 2- 170PSI

CYLINDER 3- 160PSI

CYLINDER 4- 150PSI

CYLINDER 5- 155PSI

CYLINDER 6- 160PSI

Guy from the workshop said car runs smooth as a babys behind. and really seems like the guy doesnt thrash it, middle aged and very particular owner and mechanic said car is very well looked after. then again u never kno what happens in japan. Im gona ask for a leak down test I think to be sure. what u think?

Edited by 1R34SON

When I bought my car, I had a clause on there, which was I can return the car if my mechanics testing showed the engine was not in good condition.

Did a dry compression test: 1 - 176, 2 - 175, 3 - 177, 4 - 176 , 5 - 177, 6 - 176

Did a wet compression test: 1 - 177, 2 - 177, 3 - 176, 4 - 177, 5 - 178, 6 - 178

The minimal difference in figures means that it was great compression to start with, and after using some oil to further seal the rings, the figures where almost the same (there is a variance in or 3 - 5 psi in the gauge I used). Considering the figures where almost identical, it means there is no pressure loss on the rings, meaning any pressure loss is in the valves.

a Leak-down test revealed the pistons hold very good pressure, meaning the valves are not loosing pressure, and the engine is in good condition.

Did a radiator pressure test as well, revealed no issues, did an intake pressure test, no boost leaks or other leaks,so I rang the previous owner and told him to go nuts with the money, I wasn't disappointed with the tests at all.

I later found out from a relative of the previous owner that the engine had blown, and was completely rebuilt from the ground up, forged pistons, rods, balanced crank, all the oil mods to the head, sump baffles, N1 turbochargers, etc. The works has been put into that engine to make it bullet-proof (as bullet proof as an RB26 will get), but then he had to sell for family reasons.

If you get a good RB engine, and you let them warm up before revving them and thrashing them, keep good oil to them, and dont rev them over 7,000rpm (unopened), the engine should be good for a lengthy life.

It's the other bits you need to worry about, gearbox, diff, suspension, rust through the body, but someone who knows cars will be able to pick if they have been in an accident, or if they are riddled with car-cancer.

My only advise: Dont fall in love with a car while looking, treat them all as damaged stock until you find the perfect one, and once you have purchased it, you can fall in love. (I fell in love with a 180sx yrs ago, wanted it no matter what so I wasn't maticulous in checking it out. Later found a 1 inch rust spot, took the screwdriver to it to brake all the rust out before welding a plate to the car, and the hole was 1 inch, but the rust through the panel was 1 foot 2 inches, it was HUGE!!!).

B.

Again - as stated earlier... its the % difference not the actual numbers more than anything.

Obviously if it goes

160 150 155 160 150 80

Then you have a problem, but if they are all near enough to the same number, its fine and a good result.

If you want a much better TEST - Leak Down test is the one your after

Again - as stated earlier... its the % difference not the actual numbers more than anything.

Obviously if it goes

160 150 155 160 150 80

Then you have a problem, but if they are all near enough to the same number, its fine and a good result.

If you want a much better TEST - Leak Down test is the one your after

spoke to a guy from a turbo engine tuning workshop and told me this same thing ^

he said that numbers will usually vary. and as long one isnt out by heaps or under 150 its fine. cheers all!

When I popped my stocker, it went:

Cyl 1/ 0

Cyl 2/ 75

Cyl 3/ 150

Cyl 4/ 150

Cyl 5/ 150

Cyl 6/ 150

See if you can guess which piston had a broken ringland and which had lost ring tension.

I'm guessing Cyl 2 had a broken ring land and your ring lost tension when you realised the motor needed a rebuild :(

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Had I known the diff between R32 and R33 suspension I would have R33 suspension. That ship has sailed so I'm doing my best to replicate a drop spindle without spending $4k on a Billet one.
    • OEM suspension starts to bind as soon as the car gets away from stock height. I locked in the caster and camber before cutting off the kingpin. I then let the upright down in a natural (unbound) state before re-attaching it. Now it moves freely in bump and droop relative to the new ride height. My plan is to add GKTech arms before the car is finished so I can dial camber and caster further. It will be fine. This isn't rocket science. Caster looks good, camber is good, upper arm doesn't cause crazy gain and it is now closer to the stock angle and bump steer checks out. Send it.
    • Pay careful attention to the kinematics of that upper arm. The bloody things don't work properly even on a normal stock height R32. Nissan really screwed the pooch on that one. The fixes have included changing the hole locations on the bracket to change the angle of the inner pivot (which was fairly successful but usually makes it impossible to install or remove the arm without unbolting the bracket from the tower, which sucks) and various swivelling upper arm designs. ALL the swivelling upper arm designs that look like a capital I (with serifs) suck. All of them. Some of them are in fact terribly unsafe. Even the best one of them (the old UAS design) shat itself in short order on my car. The only upper arm that works as advertised and is pretty safe is the GKTech one. But it is high maintenance on a street car. I'm guessing that a 600HP car as (stupidly, IMO) low as you are going is not going to be a regular driver. So the maintenance issues on suspension parts are probably not going to be a problem. But you really must make sure that however your fairly drastically modded suspension ends up, that the upper arms swing through an arc that wants to keep the inner and outer bolts parallel. If the outer end travels through an arc that makes that end's bolt want to skew away from parallel with the inner bolt, you will build up enormous binding and compressing forces in the bushes, chew them out and hate life. The suspension compliance can actually be dominated by the bush binding, not the spring rate! It may be the case that even something like the GKTech arm won't work if your suspension kinematics become too weird, courtesy of all the cut and shut going on. Although you at least say there's no binding now, so maybe you're OK. Seeing as you're in the build phase, you could consider using R33/4 type upper arms (either that actual arm, OEM or aftermarket) or any similar wishbone designed to suit your available space, so alleviate the silliness of the R32 design. Then you can locate your inner pivots to provide the correct kinematics (camber gain on compression, etc).
    • The frontend wouldn't go low enough because the coilover was max low and the upper control arm would collapse into itself and potentially bottom out in the strut tower. I made a brace and cut off the kingpin and then moved the upright down 1.25" and welded. i still have to finish but this gives an idea. Now I can have a normal 3.25" of shock travel and things aren't binding. I'm also dropping the lower arm and tie rod 1.25".
    • Motor and body mockup. Wheel fitment and ride height not set. Last pic shows front ride height after modifying the front uprights to make a 1.25" drop spindle.
×
×
  • Create New...