psi leanouts

Discussion in 'PSI Superchargers Tech Questions' started by pop, Aug 11, 2010.

  1. pop

    pop New Member

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    when you are running a psi screw blower,do you want leanouts to come on and off during a run or no leanouts.
     
    #1
    pop, Aug 11, 2010
  2. shawn davis

    shawn davis Member

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    They recomend a low gear leanout in the PSI manual. I havent see much if any improvement by running it.
     
    #2
    shawn davis, Aug 11, 2010
  3. Don Onimus

    Don Onimus New Member

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    leanouts

    Generally speaking, you like to put fuel back in at the shift to help settle the car down then take it away again. They use NO + NC valves from the air pressure going to the shift towers. Don Just remember the fuel curve is not even close to a roots. don
     
    #3
    Don Onimus, Aug 11, 2010
  4. Mike Canter

    Mike Canter Top Dragster
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    If you take a close look at the boost curve through the run you will see a slow average increase from the launch to the finish. A lot of this is due to the efficiency of the PSI screw blower wheb compared to the rootes blower and to the ram air caused by speed increase when going down the track. Based on all that you have to adjust the fuel curve to lean out during the first part of the run and put fuel back in during the last half of the run. Since a normal rootes type High Speed turns on right away after launch and stays on during the entire run it really doesn't do the screw blower any good and will cause a great loss of power down low and can damage the motor later on in the run due to it being too lean. Having a rootes type HS will also cause tire shake during the later part of first gear. The easiest fuel setup to start with is a Low Speed Leanout that is on from the start and is shut off at the shift to second gear. This should have a 40, a 50 or a 60 jet depending on the car or the track conditions. The 40 jet gives you the least amount of power and a 60 jet gives you the most amount of power. There are lots of variations of this Low Speed Leanout but those are tuning secrets. The Low Speed Leanout is tried and proven. The other thing is that if switching from a rootes to a PSI screw then the V slot in the barrel valve has to be modified and your idle return poppet crack pressure has to be set at a different point than that with a rootes blower. My recommendation is to get a copy of the PSI Screw Blower Manual from PSI or another racer and read it carefully. The manual is a great start out guide to get you going but is basic. A lot of us have progressed way beyond it.
     
    #4
    Mike Canter, Aug 12, 2010
  5. rb0804

    rb0804 Active Member

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    how accurate are the spring check settings to what everyone is running today? Everyone I talk to seems to think that they should be set in stone per the PSI book.
     
    #5
    rb0804, Aug 12, 2010
  6. BUTCH

    BUTCH Member

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    PSI low gear lean out

    Mike,
    Is it ok to run the low gear lean out on a normally open CO2 controlled valve with a #6 check,( and at what psi for the check?) and us the lenco air from the 1st to 2nd gear shift to close the valve to fatten the motor up? or is it better to run it off a timmer, and if so how close to the shaft should you add the fuel back in if you are having shake at the top of first gear ?

    O so wise Mr. Mike C. Can you please help !!!!!

    Thanks again

    Butch
     
    #6
    BUTCH, Aug 12, 2010
  7. Mike Canter

    Mike Canter Top Dragster
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    If running a CO2 solenoid or a electric solenoid then you don't need a poppet. The poppet will limit your flow in the low speed leanout and if using it now maybe what is causing the tire shake at the top of first. As far as when to shut off the Leanout is a tuning trick. I will tell you that shuting the leanout off right at the shift is only a baseline option. You might want to consider using the shift as a trigger for starting the timer.
     
    #7
    Mike Canter, Aug 12, 2010
  8. Mike Canter

    Mike Canter Top Dragster
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    RB if you are talking about the idle return poppet then I believe that most of us use the specified manual crack pressure
     
    #8
    Mike Canter, Aug 12, 2010
  9. BUTCH

    BUTCH Member

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    lOW GEAR LEAN OUT

    Mike, This is just the info I needed. Thanks you very much !!!!

    Butch
     
    #9
    BUTCH, Aug 12, 2010
  10. rb0804

    rb0804 Active Member

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    I was actually referring to all of the poppets as there are published 'recommendations' for the dribblers and the port nozzles also. It just seems that people seem to stick hard to what has been published. I am thinking that I would have better luck if I changed some of the pressure settings a little bit, but through talking with people they always seem to quote the PSI book.
     
    #10
    rb0804, Aug 12, 2010
  11. Mike Canter

    Mike Canter Top Dragster
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    Why does it have to be changed? I don't think that changing it will make it faster.
     
    #11
    Mike Canter, Aug 12, 2010

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