Performance First Marine Dual Turbo
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Performance First Marine Dual Turbo

  1. #1
    Pete's Pirate
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    Default Performance First Marine Dual Turbo

    Recently purchased a 1983 Cole 21 ft V-drive day cruiser with a 468 BBC PRM twin turbo set-up. This is a draw thru system with a simple intercooler attached to a single plane manifold.
    There are two intake control valves located between the outlet of the turbo and the inlet of the intercooler.
    Does anyone know what they are for? They are normally open and close with manifold vacuum.
    Dee
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  3. #2
    world's oldest teenager Dkahnjob's Avatar
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    Does your PFM system have two Holly 4 Barrel Carbs?
    The intercooler isn't very good, you might want to get a better (as in bigger Intercooler).
    The valves you are referring to are to limit boost.
    We had a similar system on my son's Campbell with a Gale Banks intercooler and waste gates.
    The biggest problem we had was with the dual 4 barrel carbs it wanted to run like two 4 cylinder engines that weren't talking to each other.
    The next owner went to a closed loop EFI system with O2 sensors, that fixed everything and it made huge HP.
    DKahnjob
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  4. #3
    Pete's Pirate
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    This PFM system has a single 850 cfm carb.

    I agree the intercooler looks small and I may search for a better one.

    I find it interesting these valves close when you lift the throttle, they are normally open and close when the manifold pressure decreases. Maybe this helps low speed response……………..

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  6. #4
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    If I'm reading this right, the valve in question is between the turbos and the intercooler.
    If that's correct, the valve would be a pop-off valve and not a waste gate. A waste gate is between the exhaust manifold and the turbo.
    I would not think a pop-off or blow-off valve would be a good idea with a draw-thru system. It would be blowing off an air and fuel mixture, which would not be good.

    Is it possible the valve would be used to release pressure if there was a back-fire through the carburetor, possibly to protect the turbo's?

  7. #5
    Pete's Pirate
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    Your are correct in the location of the two valves. They are between the outlet of the turbo and the inlet of the intercooler. They do not vent in any way, they are in line.

  8. #6
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    OK, now I'm really curious what they are for.
    Surely, someone has seen something similar before or knows what they do.
    It isn't like PFM is unknown, they were one of the name brands using turbos.

  9. #7
    Senior Member Reservoir Dog's Avatar
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    Those look like exhaust diverters (or somethings), and they do nothing because the the butterflies on your carbs do what looks like some one was trying to accomplish (?). From your turbo to the inner cooler should be strait through tube.

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