Compression Test Results Rb25det S1 R33

[RicsR33]

Hi guys just did a compression test in my R33 RB25DET

Results

Cyl 1 - 155

Cyl 2 - 155

Cyl 3 - 140

Cyl 4 - 152

Cyl 5 - 155

Cyl 6 - 157

What do you guys think of these results? Good? bad?

Is Cyl #3 to low??

All comments welcome!!!~!!

[-_-StRyDeR-_-]

test done when it was hot or cold?

put a squirt of oil in each cylinder and do the test again?

either way number 3 a little low.

[RicsR33]

sorry test was done after car was moved around the block quickly so probably cold. also test was done dry.

[toffy]

take it for a good 30 min drive , repeat test , 140psi is low but still usable ... for a while

[Trozzle]

After seeing others' compression tests on RB25's, I really question wtf was up with mine.

I'll be sure to post it up later this evening when I can give exact figures, but mine varied between 125psi and 135psi dry (unsure if warm or not tbh)

It never burns oil. Oil level never drops between services (5 - 7500kms) and I had very minimal blowby. Am now running 15psi through it, and makes 285rwkw.

Either the test was done incorrectly, the pressure tester thingywatsit is faulty, or I have a rebuilt engine with lower compression. Sorry to hijack a brand new thread, but don't spose I could get any insight on my situation?

I'll be sure to get another pressure test+leak down done when I put turbo back on and take for retune - will be at a different workshop to the first test too.

[phatlavish]

engine just has to be at full operating temp, make sure you have a good battery while cranking it, and throttlebody should be wide open

[t_revz]

i know what you mean Troy, when i drove from perth to gold coast mine used a bit of oil and i tested to find 125 on 1-5 and 6 was 120.was making 350rwhp at 16 psi. sounded low but even so kept driving. eventually opened it up and found 5 pistons had broken ringlands exactly the same size piece broken and number 6 had slightly picked up. apart from it using a bit of oil i always thought i had a rebuilt engine with low compression

[snozzle]

lol dont scare the guy

[t_revz]

his doesnt use oil though...mine was excessive on occasions

[Trozzle]

Yeah it's odd. Regardless, I'll continue driving it as is and taking care of it, until shit hits the fan I suppose. Then off to Melbourne or Sydney for a rebuildz - which we all know is when the REAL fun begins.

[RicsR33]

Yes my vechicle doesnt use any oil either, although there was a little oil in the metal intake pipe just before the turbo comp housing. Other then that the car runs quite well, besides the boost tapering off in high rpm.

[defari]

i hate hijacking threads.. i havent done a comp test but ive had a reletative compression test done (i have no idea what the difference is or if there is a difference in the comp tests) but the scale shows 0-100 on my print out.. All cylinders are 90 or above. No excessive oil use running 11psi.. no idea what power my car is making either.. I just assumed if its above 90 then it cant be alll that bad (the reason i ask is my mate said my engine is totally f**ked after reading the rel. comp. test)

Edited October 4, 2010 by defari

[D_Stirls]

^^^

sounds like you had a leak down test not a compression test, so those numbers are % not pressures.

People also have to remember that if you play with cam timing or you have different cams then comparing to factory compression figures will tell you nothing.

Edited October 4, 2010 by D_Stirls

[DVS JEZ]

^^^

sounds like you had a leak down test not a compression test, so those numbers are % not pressures.

People also have to remember that if you play with cam timing or you have different cams then comparing to factory compression figures will tell you nothing.

agreed, we gained 20psi compression just by setting the cam gears correctly after another shop set them wrong, went from 130 to 150psi on RB26

[The Mafia]

also, what kind of tester are you using?

My first tester said 120psi across all 6.

My Second Tester said 220psi across all 6.

My Third said 160psi across all 6.

As long as they are all within 5-8psi of each other.

If not, turn the boost down and wait for it to blow up gracefully.