low gear leanout on screw promod

Discussion in 'PSI Superchargers Tech Questions' started by overkill69, Aug 8, 2011.

  1. overkill69

    overkill69 Member

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    Im running an auto convertor car with soft timing downtrack but hitting it pretty hard on the start due to a poor track. It started showing some pretty good heat in the plugs so I kept richening it every round. On the last pass the egt's were a lot colder on the hit and it wouldn't come up on the 2 step. It hit 3700 and was set for 4100rpm. If I throw full timing at it downtrack it will probably be lean unless I richen the main a lot more.
    I have the Drazy style air operated leanout for low gear that i'm not using. Seems like it might help or maybe a leanout solenoid for the 2 step only?
    It's an 1/8th mile 2 spd setup.
    Thanks Mike
     
    #1
    overkill69, Aug 8, 2011
  2. sean70ss

    sean70ss Member

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    fuel

    How much fuel are you pulling out on the 2 step?????????
     
    #2
    sean70ss, Aug 9, 2011
  3. BUTCH

    BUTCH Member

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    Low gear lean out on a 206D set up

    Before we started using the low gear lean out we were dropping about 110 to 125 degrees on the egts when i went up on the converter, I started out with the poppet 5 psi under the stage rpm fuel pressure and a .065 jet and then checked my egt's at stage and at the hit, I opened the jet and dropped the poppet check psi until i got the egts were i liked it and the car would 60 foot, now we only drop about 25 degrees and the car reacts a lot better,
    What are your egts doing when you come up on the converter?
    what is your idle fuel psi?
    what is your stage fuel psi?

    I hope it helps. This is what worked for us, good luck

    Butch
     
    #3
    BUTCH, Aug 9, 2011
  4. overkill69

    overkill69 Member

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    tuneup

    I don't pull any fuel out on the two step.
    I dump 10 degrees of timing on the transbrake so the egts are only a reference but they do drop when it's on the 2 step/brake.
    I use an air throttle also so the blades are mostly shut. I'm wondering if this piles too much fuel in it. We launch with 23-26psi of boost.
    Once it launches it recovers and the egts climb but i'm afraid when I richen it to run downtrack it will be way too rich on the 2 step.
     
    #4
    overkill69, Aug 9, 2011
  5. blown375

    blown375 New Member

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    If you have an air throttle , why are you using a two step ?
    It would only make sence that your egt's will drop when you have cylinders misfireing ..... no fire no heat !
     
    #5
    Last edited: Aug 9, 2011
    blown375, Aug 9, 2011
  6. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    air over 2 step

    the theory behind using the air throttle and two step is to let the chip dictate rpm, then adjust your launch boost with blade opening. consequently, you will have to make fuel system adjustments due to bv spool positioning as you open or close the butterflies. depending on how far ahead the air opening is of the 'normal' rpm that would achieve is how hard it will get on the chip.

    so you could have too much opening for your bv spool at stage. in your case i would think it would be more desireable to have a 2 step leanout to control your stage egts/flow rather than chase the bv all over the place, because then you start changing your head temp, etc, when you're only looking to fix one specific area.

    if you are happy with the rest of the run, just not stage, fix that area.

    private message me, i have all the two step leanout stuff new in the box i'll make you a smoking deal on.
     
    #6
    Will Hanna, Aug 9, 2011
  7. sean70ss

    sean70ss Member

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    Fuel

    Well just pulling timing is not gonna do it. 6-6.5 needs to be pulled. I would post what Butch said. Your system is gonna be fat.
     
    #7
    sean70ss, Aug 9, 2011
  8. Mike Canter

    Mike Canter Top Dragster
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    Mike, do yourself a big favor and turn on that Low Speed leanout. You are acting like the Low Speed Lean out is like a High Speed Leanout on a roots blower. It is not. The Low Speed Leanout corrects the richness caused by the average boost being lower in the first part of the run. Start out with a 40 or 50 jet and if the track is good and you have a handle on the car then go to a 60 or 70 jet. You are wasting your time trying to do anything until you turn it on. Turn it on a make a few runs then fine tune the rest.
     
    #8
    Mike Canter, Aug 9, 2011
    KENNETH JORDAN likes this.
  9. overkill69

    overkill69 Member

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    tuneup

    Mike C I understand the low gear leanout. My car is rich on the bottom and getting lean up top. When I fatten the main it will be worse. The leanout should help everything cleanup until it shifts and then it will richen.
    I have the leanout already on the shelf but most guys are saying to just leanout the 2 step with a solenoid. If i'm going to buy a solenoid i'm going to get a management block as I already have a timer setup.
    I thought the deal would fly without any management. If it's a requirement I might as well start using it and not waste anymore passes with a single leanout setup.
    We've blown the budget for sure getting it running, just trying to buy/use the pieces that will make the most bang for the buck.

    Thanks for all the responses guys,
    Mike
     
    #9
    overkill69, Aug 10, 2011

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