Bog on launch

Discussion in 'PSI Superchargers Tech Questions' started by pentastarrail, Jun 29, 2009.

  1. pentastarrail

    pentastarrail Top Dragster

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    Hi guys,
    I have an issue when it's hot and muggy out (at least that's when it seems worse).
    The car is a TD, 526 hemi, 1471 with a Powerglide.
    What happens is when I deck the throttle it initially comes up and hits the 2 step (2400 rpm) but then seems to flood (for lack of a better word) and the RPM drops to about 1200 and then bogs when the transbrake releases.
    I do have a throttle control on it which is just opening the throttle blades/barrel valve very little until the brake releases and then slowly opens.
    I do have air bleed valves on the side of the injector (Big Ugly) that I could open, (I ran out of testing time this past weekend -- rain).
    Do you think if I open these for the run that it will help since it will give it a little more air with less fuel?

    Any other ideas would be great.

    Thanks
    Frank
     
    #1
    pentastarrail, Jun 29, 2009
  2. Mike Canter

    Mike Canter Top Dragster
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    So are you saying this doesn't happen on cooler, drier days?

    Do you read the weather to get the Density Altitude and adjust your tuneup for different DA's?

    Since you are not at wide open throttle on the 2 step because of the throttle control the idle mixture plays a big part in the staging fuel. Have you tried leaning out the idle by using a smaller leakdown percent on the barrel valve?
     
    #2
    Mike Canter, Jun 29, 2009
  3. pentastarrail

    pentastarrail Top Dragster

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    Hi Mike,
    Correct, on cooler days it is fine.
    As far as adjusting the tune up, I "usually" don't do much since I just bracket race it.
    Adjusting the BV is a good idea. I'll try it this coming weekend (test day before the race).
    I just ran out of time this past weekend and are trying to get a little closer with it for our Divisional race this coming weekend.
     
    #3
    pentastarrail, Jun 29, 2009
  4. Mike Canter

    Mike Canter Top Dragster
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    You really do need to read the weather and compute the density altitude. You don't have a weather station for bracket racing? If you do try going back through your records for your best MPH run and take that main jet and that Density Altitude and make that your reference baseline. Now for every 500 ft increase in DA increase your main jet by 5. For every 500 decrease then make the main jet 5 smaller. It should really help. Also put the leakdown tester on the barrel valve and see what percent it is. Then change it 4-5% down and see if it helps. I wouldn't try and guess it because you will lose where you are. If you don't know the procedures for doing a BV leakdown then email me at mike.c@mindspring.com and I will email them to you.
     
    #4
    Mike Canter, Jun 29, 2009
  5. jim phillips

    jim phillips ta/fc

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    you deffinitly need a weather station if it ok when it cool it probley way fat when its hot and humid got to lean it down a little on the main
     
    #5
    jim phillips, Jun 29, 2009
  6. GregM784

    GregM784 Member

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    Or turn up the air. If the air goes away, catch it with pulleys. (that's why they come in all sizes. :))
     
    #6
    GregM784, Jun 29, 2009

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