Nozzle percentage...

Discussion in 'PSI Superchargers Tech Questions' started by Kerry Grams, Dec 8, 2011.

  1. Kerry Grams

    Kerry Grams New Member

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    Just for educational purposes, what % of the total nozzle area do you guys run in the top/bottom?
    Thanks,
    KG
    www.blackreignracing.com
     
    #1
    Last edited: Dec 8, 2011
    Kerry Grams, Dec 8, 2011
  2. Mike Canter

    Mike Canter Top Dragster
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    Try for as much in the top as possible. The only thing you really need port jetting for is to balance the EGTs. 65-75% in the top is good. The problem is that the more you put up top the smaller the port jets get so you run the risk of blockage. I don't like to go any smaller than a 38 jet in the ports. You need a good inline fuel filter or BV screen in the inlet.
     
    #2
    Mike Canter, Dec 8, 2011
  3. aj481x

    aj481x Member

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    How about 100%-0% ? :p
     
    #3
    aj481x, Dec 8, 2011
  4. Mike Canter

    Mike Canter Top Dragster
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    That would be great but there is a point where the cooling effect stops after putting so much alcohol into to the top. I had a fellow engineer compute it out for me a few years ago but can't find where I put the data.
     
    #4
    Mike Canter, Dec 8, 2011
  5. rb0804

    rb0804 Active Member

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    Which do you prefer the screen at the BV or the filter? I run the screen in the barrel valve currently and I check it every run. You will be amazed the stuff that finds its way in there.
     
    #5
    rb0804, Dec 8, 2011
  6. Mike Canter

    Mike Canter Top Dragster
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    The whole trick is to stop a dirt particle that is larger enough to block a jet. The screen seems to do an adequate job. The inline filter does and excellent job also. If you think the screen catches stuff then you should see what a filter stops. I do not know where it all comes from. The screen will have least effect on flow. The inline filter reduces flow a little more. If you have a flowmeter then it is easy to compensate for. If not then you need to go a little richer.
     
    #6
    Mike Canter, Dec 8, 2011
  7. Blownalky

    Blownalky Top Sportsman

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    Are the suggestions for a Roots or a Screw and does it matter?
     
    #7
    Blownalky, Dec 8, 2011
  8. Mike Canter

    Mike Canter Top Dragster
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    The percentage of fuel talked about is only for Roots blowers.
     
    #8
    Mike Canter, Dec 8, 2011
  9. aj481x

    aj481x Member

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    Looking forward to this explanation. :cool:
     
    #9
    aj481x, Dec 9, 2011
  10. Mike Canter

    Mike Canter Top Dragster
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    Give me some time to get hold of the guy and have him write up an explanation at a level I can understand (lol)
     
    #10
    Mike Canter, Dec 9, 2011
  11. Patrick Hale

    Patrick Hale Member

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    Swamp Coolers

    Mike, aj481x - let me repeat something I posted a few months ago on this topic:

    Many people have an evaporative cooler in their home or shop. A squirrel cage blower is used to force the outdoor air past a cascade of water in order to evaporate the water and cool the air going into the house. We call them swamp coolers in Phoenix and they work great when the air is hot and dry. However, when the humidity is high, like our “monsoon season”, they don’t work well and we have to turn on the AC. Evaporative coolers increase the humidity of the air to almost 100%, also known as the saturation point, to efficiently cool the air before it goes into the house.

    All the fuels used in racing (gasoline, methanol, and nitro/alky mixtures) have the same kind of thermodynamic properties of evaporation as the water used in the swamp cooler. The Top Alcohol engine has a blower to “gulp” the outdoor air and pass it through an injector that is spraying methanol everywhere to get it to evaporate. Methanol is particularly good at cooling the air, much more so than gasoline or nitro. The air can also hold a lot more methanol vapor before 100% saturation occurs and has a lower boiling point (148 degF) than water (212 degF).

    The concept of "fuel saturated air density" is just like the swamp cooler. We take the ambient air and spray/mist/evaporate fuel into it to cool the air to the maximum extent possible, i.e. down to the saturation point. For example, the standard weather rating conditions for motorsports are a sea level barometer (29.92 in Hg), 60 degF and dry air (0% humidity). If we take methanol, also at 60 degF, and spray/mist/evaporate it into a container filled with 60 degF air it will lower the temperature down to 14 degF. Simply amazing!

    The cooling effect of the methanol evaporation is different for every combination of ambient weather conditions and fuel temperature. When the ambient air is filled with water vapor, it is harder to evaporate the methanol and cool the air. The water vapor is taking up space that the methanol vapor would like to occupy. Also, when the ambient air is colder, much less methanol can be evaporated. So the amount of cooling will be different for every combination of weather conditions, and for every type of fuel, or fuel mixture.

    “FuelSat Air Density” describes the density of the air at the inlet to the blower. Classic definitions of “Corrected” or “Density Altitude” just don’t apply to the supercharged engine. The density of the air as it enters the blower is critical for supercharged engine fuel system tuning . . . not the air density calculated back in the pits using the ambient temperature.

    Patrick Hale
    www.DragRacingPro.com
     
    #11
    Patrick Hale, Dec 9, 2011
  12. Mike Canter

    Mike Canter Top Dragster
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    Thanks Patrick, that saves me from writing the explanation and yours is easier to understand using "swamp coolers";).
     
    #12
    Mike Canter, Dec 9, 2011
  13. Kerry Grams

    Kerry Grams New Member

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    Mike, check your pm's please.
    Thanks,
    KG
     
    #13
    Kerry Grams, Dec 9, 2011

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