Fuel Pressure / Why

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by lucky devil, Sep 27, 2016.

  1. lucky devil

    lucky devil Member

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    I am looking forward to the answers already......
    There is so much great experience on here.

    My question is why is it not seen to be effective to run Fuel Pressure at say 200PSI ? would it not atomize better ?

    Sorry if this is a basic question to ask for some , but Iam always interested in real world experience from racers and tuners.

    Thanks Wayne
     
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  2. Comax Racing

    Comax Racing Member

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    The reason I have discovered not to run pressures up that high is you tend to bend/twist pump shafts over time. As far a performance, I'm going to defer that to the more knowledgeable.

    Corey
     
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  3. jay70cuda

    jay70cuda Member

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    Well look at efi now. They used to have a very large pump and return line. Now you see most systems are no return line and much less psi. You have to turn that pump when your not using all the fuel needed at idle and climbing thru the rpms . That's what I gather out of It
     
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  4. aj481x

    aj481x Member

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    Many good tuneups, that add fuel going down the track are setup to hit around 200 psi at the finish line.
     
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  5. jay70cuda

    jay70cuda Member

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    Not in a roots? Screw motor ?
     
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  6. lucky devil

    lucky devil Member

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    yes , i should have said.....roots blower deal
     
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  7. Mike Canter

    Mike Canter Top Dragster

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    I think using our type nozzles there is a point that you get max atomization and going above that point makes no difference. I have tried it all the way up to 200 psi and know somebody that went to 400 psi. Never seen a difference in performance. I think what happens with our current nozzles at too high of a pressure is that it just squirts acrosvand hits the runner wall and runs down as a liquid. What we need is a better nozzle something that shapes the flow better down the center of the runner or maybe even spin the fuel mist. I think that maybe something other than the fuel hitting a flat deflector on the end of the nozzle would be better. If somebody has made something better out there then they are sure keeping it s secret. Darren Meyer this should be right up your alley.
     
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  8. lucky devil

    lucky devil Member

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    Hi Mike , thats just what i have been thinking...any more thoughts guys
     
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  9. mike sullivan

    mike sullivan Member

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    Don Jackson makes a nozzle like your talking about
    714 269 9645
     
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  10. turbo69camaro

    turbo69camaro Member

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    I know there are 2 EFI nozzle designs one has a beautiful atomized cone pattern the other looks like a garden hose .in back to back dyno test there was no power difference. with a valve opening and closing 80 times a second and you have to get X amount of fuel in that cylinder in that time.
     
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  11. Blownalky

    Blownalky Top Sportsman

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    When I started looking into EFI and learning about batching, I started to understand that there was fuel flowing when the valve was closed (duh on me) just like our constant flow mechanical injection. If the valve is closed, it seems to me that the fuel is going to just puddle until the valve opens again. So the above statement where the pattern would not be that big of a deal makes sense. Maybe I'm missing something but the only time I would see that atomization would be possible is during the time the intake valve was open and the fuel would be mixed with the moving air.
     
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  12. jay70cuda

    jay70cuda Member

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    The current efi on a super charged engine is using nozzle bodies we already use but with those electronic valves on the top of the blower to control it.
     
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  13. rb0804

    rb0804 Member

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    http://www.ragefuelsystems.us/

    Anyone using the spraybar that is shown in the lower right corner of the webpage? I did an internet search and didn't see any other info out there besides the video. 80hp is a big claim, anyone have inside info on what type of nozzles the spray bar is superior to?
     
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  14. Mike Canter

    Mike Canter Top Dragster

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    A couple of things here. Since the spraybar is in the hat the biggest thing it does is to cool the incoming air because when it goes down into the mixmaster of the blower rotors then it is all combined. Second if you fuel pools on the runner walls or behind the valve the the mixture in the combustion chamber is going to appear lean because the fuel is now droplets instead of a fine mist. The droplets cannot burn as fast or as completely as a fine mist.
     
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  15. jody stroud

    jody stroud ZOMBIE Top Dragster

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    The spray bar works as advertised
     
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  16. rb0804

    rb0804 Member

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    If this were true we should see an increase in efficiency and power as we increase the fuel pressure for better atomization.
     
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  17. greenracing

    greenracing Member

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    Since the the valve is closed more than it's open - a 280 duration cam has the valve open 78% of a revolution every other revolution, so the valve is only open 39% of the time. During the time when the valve is closed, the fuel's spraying in, the blower is cramming a fuel mixture that's likely not that atomized after going through the mixMaster - it seems like you're going to get pooling on the runner and the back of the valve no matter what your nozzle spray pattern looks like. I think that may be why turbo69 saw no difference between the spary patterns on the dyno.
     
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  18. Mike Canter

    Mike Canter Top Dragster

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    Rb0804, what I said was if you increase pressure to high then I believe with the type nozzle we use then it hits the deflector on the end and then hits the runner wall and streams down the wall. The other thing we have to take into account is air stream velocity. Velocity stops pooling on the manifold floor and hopefully helps when all hits the valve
     
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  19. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    Higher fuel pressures also change the flame front of the fuel....
     
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  20. Mike Canter

    Mike Canter Top Dragster

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    Will, can you explain that more since the intake valve is closed during that part of the cycle and no fuel is being injected into the chamber.
     
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