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Thread: Blow thru turbo 32/36 boost reference

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    Blow thru turbo 32/36 boost reference

    Probably an idiotic question but thought I'd try confirm. If a 32/36 is boosted, will the port which normally has vaccum reference for the distributor now be boost referenced? So for a rising rate for based on boost (one like a metro turbo item) be connected to the carb this way? Or will I need to make a union before the carb? Hope this makes sense. Cheers

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    Re: Blow thru turbo 32/36 boost reference

    same connection if you ask me, its no different to running map sensors on efi, they have to go in the plenum between throttle plate and engine

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    Re: Blow thru turbo 32/36 boost reference

    The vacuum port for the distributor on a 32/36 is just above the throttle plate at idle.
    So at idle this is not the same as manifold pressure.

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    Re: Blow thru turbo 32/36 boost reference

    But that would then mean I could take a reading off a port in the inlet manifold? I thought it had to be before the carb. So between turbo and carb butterfly? I.e. Inlet plenum like on the r5 turbo's. They have the reference going to the regulator off the top hat/plenum. Just didn't know if the vaccum port in the 32/36 was read before or after the throttle butterflies and wether it'd make a difference

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    Re: Blow thru turbo 32/36 boost reference

    You normally connect to the hat/plenum on top of the carb so the fuel pressure raise with the boost pressure so fuel pressure stay same over the float needle. If there is 300 mbar, boost to 700 mbar the fuel pressure should now be 1000 Mbar. Needle still see 300 mbar.

    If you connect to the vacuum side of the manifold and fuel pressure is 300 Mbar, it will be lowered the pressure to lower value's but at the same moment there can already be boost pressure on the other side of the valve plate. Can be a problem if this boost start to be higher as the fuel pressure boost. Remember, you work with small boost in a carb. Possible the fuel pressure is just going to be higher as the boost pressure and would in theory be an advance, less boost at idle mean better fuel control over float so you can fit a bigger needle for full power fuel supply. Not sure it will work.

    There are boost reference for carbs (Holley Turbo) who are also "raising rate" (like in cheaper EFI turbo kits). They don't work linear and add more boost in relation to real boost pressure to overcome fuel starvation at high speed WOT. But as far as I know, also connected to the hat / plenum on top of the carb.

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    Re: Blow thru turbo 32/36 boost reference

    Tap a port into the plenum it is! Cheers

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