Roots blower fuel distribution 50/50, 60/40, 40/60

Discussion in 'PSI Superchargers Tech Questions' started by rb0804, Dec 23, 2017.

  1. rb0804

    rb0804 Active Member

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    What’s everyone’s thoughts on hat vs port fuel distribution? 50% in the hat 50% in the ports? Seems like it should be a pretty good balance of fuel and air? What about 60% in the hat and 40% in the ports? The idea here would be to dump extra fuel in the hat to help cool the incoming charge making it more dense with the ports helping to even everything out. The last option is to dump 40% in the hat and 60% in the ports which in theory, there is less fuel and more air to compress which should raise boost correct? Or does the increase in air temp due to the less fuel (cooling effect) increase boost? Which one is faster on the track? Would your choice vary if we were to throw in a spray bar in the hat and/or down nozzles instead of the standard port nozzle location? Any and all experience or opinions welcome; thanks for the space.
     
    #1
    rb0804, Dec 23, 2017
  2. Mike Canter

    Mike Canter Top Dragster
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    You want as much fuel in the hat as possible to cool the air, lubricate the strips and seal the blower. You don’t want to go too small on port nozzles because they become easier to get blocked by debris. Normally I try and stay in the low 40’s on the ports with maybe one or two in the high 30’s. Same with a spraybar. Normally need to take out a pair of hat nozzle when you add a spray bar and keep it up in the 60% still
     
    #2
    Mike Canter, Dec 23, 2017
  3. Comax Racing

    Comax Racing Member

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    Sorry to hijack but i hope this is along the same line. I am looking at a new LB22 and that blower has 6 spots for nozzles on the back of the blower. I have an old littlefield (LB-8 i believe) and it has only 2. Does a person have to use all of the 6? That would change the fuel going into the engine by a huge margin. Whats the proper way to deal with the other 4 nozzle holes?

    Again sorry to hyjack
    Corey
     
    #3
    Comax Racing, Dec 24, 2017
  4. Mike Canter

    Mike Canter Top Dragster
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    Where are the six located. Are there any underneath the back of the blower? All you have to do is add the area of all the jets you have in the top of the blower and hat then keep that area the same when you add the additional nozzles. So probably have to are the others smaller. Easy to do on paper or with Jetsize. I can send you a sheet with all the area and flows if you need it. Or send me you jet sizes and how many you want to use on the new blower and I will have my Alky Pro software compute it for you
     
    #4
    Last edited: Dec 24, 2017
    Mike Canter, Dec 24, 2017
  5. andy wilfong

    andy wilfong Active Member

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    We put the six spots in the blower because some restraints block certain areas, that gives the customer multiple choices to choose from, we suggest the two furthest to the rear
     
    #5
    andy wilfong, Dec 25, 2017
  6. Comax Racing

    Comax Racing Member

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    Thanks Andy I was hoping you might advise about why there are 6 holes. That answers my question.
    Corey
     
    #6
    Comax Racing, Dec 27, 2017

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