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Thread: VR4 TRUTH!!!!

  1. #1
    SCH Member
    Join Date
    Nov 2009
    Lawrence, KS

    VR4 TRUTH!!!!

    Does anyone even know? Guys post how they are comparable to a 2000 or a ysi with a high performance impeller. The mr granatelli himself tells me they max at 14 to 1500cfm before cavitation and hot air only, plus they max at 15 psi regardless of cfm due to case design clearances. I never rebuilt the one I have. People tell me it wont make 2 psi on my 415, but guys here using one on a 454 with somewhere north of 8 to 10psi.

    Mr G. Told me that to set the unit up for full potential, the pressure on the balls is what fails them. But you just rebuild it all the time since it's a race blower, no biggie. New balls. The pressure kills them regardless of what lube mods you do.

    So to set a vr4 up with regular sn pressures, how much cfm/psi can one get? Can my 415 get 8 or even 10 psi on steerable reliable ball pressures? How is the guy with the 454 doing it? Grrrrrrr.
    Last edited by 69fury; 02-26-2020 at 02:02 PM. Reason: Tags

  2. #2
    Junior SCH Member 69mustangGT's Avatar
    Join Date
    Nov 2011
    Its my understanding, The tighter pressure on the Balls is to make up for the Increased pressure the Impeller will make to avoid Ball slippage on the shaft which will cause increased heat and ball and impeller shaft to fail. With the VR4 it is definitely recommended to use an Oil cooler, keep the oil clean, change it often if raced. with my set up I am Planning on adding a water injection system to cool the output air and condense it. The other thing to look at is the Cam, Make sure there is no less than a 12 deg lobe separation preferably 14 deg. to keep the pressure in, Make sure it is a supercharger cam.

  3. #3
    Junior SCH Member
    Join Date
    Feb 2013
    I would like to know all of this as well. I understand it's a outdated blower but I can't seem to find any hardcore info on the VR4. I have one and am in the process of putting on my 93 Lightning.

  4. #4
    Junior SCH Member
    Join Date
    Jun 2009
    New VR4 Billet Impellers are now available from Supercharger Rebuilds out of Dallas.

    They offer rear housing modifications for the larger VR4 Impeller Upgrade as well.

    you can email them at or

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