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View Full Version : RB25DET compression.

NA4NOW
09-20-2006, 09:25 PM
This 240 Im looking at has a rb25det swap. I asked the owner to do a compression test. He said the lowest was 135, and the highest was 145.

Does this sound like its in spec.?
LB.Motoring
09-20-2006, 09:33 PM
155 across the board is what you want...
those are a little low ^

but understandable

not tooo bad, but 135 is a little low...
eh?
09-21-2006, 07:28 AM
About 170 is spec. If the psi range is within 10 the motor is usually ok. But 135 is very low. It's possible to just have a gauge that don't read correctly. Is there no way you can test yourself?
AS240
11-26-2009, 05:26 PM
bringing this one back from the dead.
i just compression tested my S2 rb25 while it was still warm. wot and fuel pump off. using a us general compression tester...i got 140 across all cylinders. the gauge didnt have a one-way valve so it would peak at 145 and drop back to 140. sound normal? i keep reading of people getting higher numbers and im a little concerned.
fcdrifter20
11-26-2009, 08:55 PM
over the years of natural wher and tear thats sounds about normal
Zacho
11-27-2009, 12:04 AM
nissan manual says rebuild 129 psi.

however, many different ways to go about compression testing.
GSXRJJordan
11-27-2009, 01:00 AM
Sounds like the motor's a little tired, but as long as they're all within 5 or 10 psi of each other, you're fine. Drive it.
eklips3
11-27-2009, 04:48 PM
between 135 and 145 is a tad low , but the motor is still good , just a little used. i say go for it and take good care of the motor
BlitzRPS13
11-27-2009, 06:24 PM
Did he do it warm or cold? Also it needs to be on a battery charger aswell.
AS240
11-28-2009, 04:26 PM
it was warm and the battery is a fresh optima red top. i got the motor about a year or so ago and have been dailying it in my s13 since. i pulled the valve covers when i got it and it looked prestine. only had ~20km. its a strong motor. i made 315whp on a mustang dino with the stock turbo. im just curious because a 35r or a hx35 are my next plans. thanks for the replies
BlitzRPS13
11-28-2009, 04:32 PM
I would go ahead with it then.. and if you blow it up.. put forged pistons in it. If not.. enjoy.
GSXRJJordan
11-28-2009, 07:24 PM
I would go ahead with it then.. and if you blow it up.. put forged pistons in it. If not.. enjoy.

Agreed 100% lol.