Transmission Bypass Valve

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by 57Chev, Aug 18, 2018.

  1. 57Chev

    57Chev Member

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    Looking for some feed back if there was any advantage with the Transmission Bypass Valve on Screw blown Auto?

    Thanks
     
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  2. blownapex

    blownapex Member

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    i would be interested also
    1- might specify trans type and what mods you have to make in the
    transmission to control the pressure
    2- also what should the data log pressures be ( high and low)
    do you remove input shaft bushing
    3- how much rpm does this drop
    4- i have a lenco drive who do i send it to to get this converter pressure control added
    5- i would like to loosen converter rather than pull timing to control wheel speed
    thanks
     
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  3. Blown5402

    Blown5402 Member

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    And are you running a lock-converter??
     
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  4. 57Chev

    57Chev Member

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    It's a Lenco Drive two speed. No Lock up.
     
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  5. rb0804

    rb0804 Member

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    I have setup several of these and they are more effective if you can take the line tap out if the valve body after the converter pressure regulater and check valve vs. externally on the “cooler circuit”. This also gives you the option to flow through the converter while on the cooler if you plumb it correctly. You can choose to control it however you like, with an adjustable pressure regulator, multiple jets with some sort of electronic controller, or only at stage for a “spool valve”. The trick is knowing when and where to use it. There’s a reason that NHRA banned the use converter fluid manipulation....
     
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  6. Mike Canter

    Mike Canter Top Dragster

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    Did NHRA totally ban it? I heard NHRA allows it in first gear/launch only?
     
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  7. rb0804

    rb0804 Member

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    From the promod section of the rule book:

    “Iterative transmission staging device permitted on converter cars. Manipulation of transmission or converter pressure or volume other than at the starting line is prohibited. Pressure manipulation control must be disarmed upon the release of the transbrake or any other device used when launching the vehicle. See General Regulations 2:12, 2:13, 2:14.”
     
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  8. Mike Canter

    Mike Canter Top Dragster

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    Interesting. Ok, thanks
     
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  9. TD381

    TD381 Member

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    Where and how on the valve body do you tap into the converter charge pressure passage? Any pictures? Thanks, Steve
     
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  10. rb0804

    rb0804 Member

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    Here’s some pics of the last Lenco Drive that I did. I drilled and tapped the valve body and the case. The case I did so I could use a # 6 bulkhead fitting and snaked the line from the converter feed circuit around and out of the case. The valve body I did in 1/8” pipe to #6 90* fitting so I could clock it where I needed it. Drilling and tapping magnesium is a little tricky, and magnesium chips are combustible and will burn intensely white, so use caution if you decide to do this type of mod.

    Once outside the case it then goes to an old 4 port air operated Hartman fuel log that I had laying around . I use the Leahy command module to operate 4 electric over air solenoids that open up the fuel logs’ plungers. With no power the log is closed and converter circuit operation is normal. I can open one jet or four jets or anywhere in between to fine tailor the converter pressure to fine tune the Converter and get it to do exactly what I want. Different valve bodies have different circuits in different spots, so modify at your own discretion and as always, your results may vary.
     

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  11. TD381

    TD381 Member

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    If I can call you please email # to: sotacd@comcast.net
    Thanks, Steve
     
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