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Thread: rb25 compression test

  1. #1
    GTRCer dkfaiosantos's Avatar
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    rb25 compression test

    Hi guys, I just did the compression on my rb25det and found something wird about it, so info is appreciated.As I know the fsm says 185psi factory compression, 142psi minimum acepted and 14psi diference between them, so the thing is that my compression shows (I've done it with Wide Open Throttle for about 7 sec., all spark plugs disconnected.)
    #1

    #2

    #3

    #4

    #5

    #6

    I'm not sure about the firing sequence, but I thing it is 1-5-3-6-2-4, is this right?
    If yes I have #1=180psi-#5=190psi-#3=190psi-#6=190psi-#2=190psi-#4=180psi.
    Can this motor been done something like cams or something to get that much? I got really surprise when I saw that the motor is really really clean and with these # too.
    So let me know what u think about it!

  2. #2
    GTRCer Voodoo_ChildR32's Avatar
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    My old RB20DE N/A had 180psi per cyl. and it was running 10:1 compression. I'm not sure, but isn't that a little high for a turbo engine?

    How much boost r u running?

  3. #3
    GTRCer dkfaiosantos's Avatar
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    I found a fsm where they say it should be 185psi standart factory, 142 is the minimum accepted and they can have 14psi diference between them, I think that my motor has something done on it, I did the compression 4 times just to make sure and all the times they were the same #, so or it is really f**** or it has something done to get that compression.
    The motor was too clean for my like, but I'm not sure about what it means with that compression.
    Any info is appreciated!!!!

  4. #4
    Mr. Sarcasm canadianskyline's Avatar
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    Can you see the vtc solenoid on the head on the driver side? Just beside the coolant neck there should be a piece coming out of the side of the head, it's cylinderical, about 15mm diamater, and has a hex head on it (and has wiring clipped to it, has 2 pins).

    If you dont have that then yours could be an rb25de gone det.
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  5. #5
    judasentinel's Avatar
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    Quote Originally Posted by canadianskyline View Post
    ........If you dont have that then yours could be an rb25de gone det.
    I had an RB25DE just a few months ago and now have RB25DET, and BOTH have the NVCS on them. While the DE is known to have a higher compression than the DET, there must be another way to distinguish it from the DET. See this:



    You cannot tell if its a DE or DET by the looks of it.

    And funny that you say your CR is coming so high, Fabio. Mine on my existing RB25DET is also the same - 185-200 across all cylinders. So I'm a bit perplexed too, considering the FSM says it has to be a bit lower than that. Could it be due to something sticking in there?
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  6. #6
    GTRCer dkfaiosantos's Avatar
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    I know that if U put some oil into the spark plugs holes you'll get more compression due the fact that the oil will make like a seller in the piston's rings making the compression higher, I did put some oil to make sure if my rings were ok after I've done my compression and it went up to 210psi, it's crazy, it seems that I have a high compression pistons in place of low compression pistons,my motor is for sure a rb25det not rb25de+t,I have some pics of my motor.Another thing that I saw was that my timing belt was done at 96xxxkm and my top end is really too clean.I think "not sure" that someone back in Japan did cams on it, but I'll try to see what do I have just to make sure.


  7. #7
    GTRCer kelaog's Avatar
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    Is that an r33? you live in toronto? How'd you get one already? :

  8. #8
    judasentinel's Avatar
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    Quote Originally Posted by kelaog View Post
    Is that an r33? you live in toronto? How'd you get one already? :
    Hey kelaog,

    Its just the front half cut. But still.......lol.......

    check out his other thread on the subject. you can see the complete front clip here:

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