Turbos and LPG
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Thread: Turbos and LPG

  1. #1
    Guru davemcbean's Avatar
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    Default Turbos and LPG

    I was just reading the Gas Research website and they said something which indicates there might be such a thing as a gas mixer which you can blow through.

    Does anyone know if this is true?

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    I didn't think this was possible. I thought all LPG turbo systems sucked through the mixer (even if they blow through the throttle).

    Dave
    NZ Fleet
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    1991 205 SI 1.6GTI motor
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    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by davemcbean
    I was just reading the Gas Research website and they said something which indicates there might be such a thing as a gas mixer which you can blow through.

    Does anyone know if this is true?

    I didn't think this was possible. I thought all LPG turbo systems sucked through the mixer (even if they blow through the throttle).

    Dave
    I've only ever seen a suck through mixer on a VL Commodore. I think it was at an LPG place at Riverstone from memory. The best guy to ask is at Warners Bay, Newcastle. He's the absolute god of all the LPG people in NSW. Can't recall the name though.

    '92 205 Mi16
    '90 Mi16x4

  3. #3
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    Even the old style mixer rings and converters can be adapted very easily to blow through operation...

    Every Otis ring LPG mixer operates on a blow past principle.

    The higher the air velocity past the ring, the more vacuum is created (nothing to do with maniold vacuum as it is before the butterfly)

    All that is required is a balance line from manfold to the atmospheric side of the converter diaphram...

    This equalizes the atmosphere side of the diaphram with the boost pressure, returning the situation to an equilibrium and allowing the velocity of air to meter the LPG. It basically fools the coverter into thinking there is no boost.

    Most LPG coverters actually have a balance pipe which makes it very easy to connect.

    The ring can be placed between Intercooler and TB, aslong as the equalizer pipe is in the same vicinity as the mixer.

    DO NOT suck through the turbo (esp with an intercooler), as any backfire is likely to blow the bonnet clear of the car...
    Last edited by mistareno; 20th September 2004 at 09:28 PM.

  4. #4
    Fellow Frogger! jarrods's Avatar
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    Quote Originally Posted by davemcbean
    I was just reading the Gas Research website and they said something which indicates there might be such a thing as a gas mixer which you can blow through.

    Does anyone know if this is true?

    I didn't think this was possible. I thought all LPG turbo systems sucked through the mixer (even if they blow through the throttle).

    Dave
    Down here in VIC all the turbo pugs (at least 505 and 504) are running blow thru gas research carbies. Gas research has proven to be the most successful after lots of trial and error. To date there is 1 x twin turbo V6,(soon to be 2), 2 X single turbo V6 and 1 X turbo GTI. The gas research system is more of a carbie than a mixer which allows much better tuning. Draw thru setups are more a thing of the past and have all the problems posted above as well as icing up of the butterflys and not being able to run an intercooler. Even with the blow thru setup you still dont' want a backfire as the V6 twin plenum manifold holds a lot of gas, enough to bend valves, butterflies or both.

    Jarrod

  5. #5
    Fellow Frogger! 505 to the max's Avatar
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    I'm about to decompress my 505GR (with worked GTi motor) and fit a GT25 and wind some boost into it. Does anyone know what sort of boost the standard Pug bottom end will handle with 8.5:1CR? The more boost the better but a rebuild may cost me dearly....

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    Guru davemcbean's Avatar
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    Richard, Jarrod,

    Thanks! That's great to know. Yeah the backfire thing was the thing which worried me with a suck through mixer, plus the fact that a mix of LPG and air touching a hot turbine sounds pretty dodgy. I didn't want the mixer sitting up near the nose of the car either, where an accident would force it up against the hot turbo. Blow through is definitely the way to go.

    I was kind of hoping you'd say blow through wasn't possible, because now I'll be too tempted to turbo my 505, seeing as I already have the turbo and manifolds and nearly all the other bits needed to convert my car lying around (the system that was previously fitted to Peter Boorman's 504 in the 1980s and Micheal Loney's 504 in the late 1990s). The bottom end currently in my car is actually the decompressed 2 litre which was in those cars previously. I also have a 2.25" exhaust system lying around which will match up nicely to the big down pipe which comes off the turbo.

    My understanding is that getting an Engineer's certificate for a turbo conversion is fairly straight forward (no emsssions problems), so long as you run straight LPG.

    Now, I wonder if I can get a torroidal LPG tank which will fit in the place of my standard fuel tank (with a suitably tough guard mounted around and below it).

    Dave
    NZ Fleet
    1976 504 Ti
    1984 205 GT twin carb
    1991 205 SI 1.6GTI motor
    1994 106 Xsi
    1996 Mondeo V6
    Aus Fleet
    1955 203C
    1997 Civic Cxi (great allrounder- revy, flexible, nimble, comfortable , economical, simple and durable )

  7. #7
    Guru davemcbean's Avatar
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    OK, what's a Gas Research mixer worth?
    NZ Fleet
    1976 504 Ti
    1984 205 GT twin carb
    1991 205 SI 1.6GTI motor
    1994 106 Xsi
    1996 Mondeo V6
    Aus Fleet
    1955 203C
    1997 Civic Cxi (great allrounder- revy, flexible, nimble, comfortable , economical, simple and durable )

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