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Compression Results On 34gtt

1R34SON

By 1R34SON,
in General Automotive Discussion

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1R34SON Proficient

1R34SON

Posted
Posted

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!!

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Pattygtst Veteran

Pattygtst

Posted
Posted

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

Pattygtst Veteran

Pattygtst

Posted
Posted

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

1R34SON Proficient

1R34SON

Posted
  • Author
Posted (edited)

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
turbo_brian Community Regular

turbo_brian

Posted
Posted

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.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

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

1R34SON Proficient

1R34SON

Posted
  • Author
Posted
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!

Kinks Grand Master

Kinks

Posted
Posted
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 :(

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