Fuel Gallons per Horsepower
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Fuel Gallons per Horsepower

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    Senior Member VDRIVERACING's Avatar
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    Default Fuel Gallons per Horsepower

    Anyone have a formula to determine fuel needed with specified HP for supercharged engine at a given ci and boost?

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    Senior Member Factory1's Avatar
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    I'll get the ball rolling here and say I think you are going to have a tough time with that one. I would think at minimum you would also need to have an rpm to go with that equation. I know the dyno cell we use has a flowmeter inline in the fuel supply to measure flow, so there are instruments out there for measuring it. But I think the bigger multiplier is going to be your right foot!

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    Won't be able to tell unless you use a dyno with a flow meter. Weird things happen at different throttle positions. Just because you use a certain amount at WOT, doesn't mean shit. you might use more gas in the midrange. I just did a dyno on wednesday, the motor used a lot more fuel in the mid range than at WOT.
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    Quote Originally Posted by widowmaker View Post
    Won't be able to tell unless you use a dyno with a flow meter. Weird things happen at different throttle positions. Just because you use a certain amount at WOT, doesn't mean shit. you might use more gas in the midrange. I just did a dyno on wednesday, the motor used a lot more fuel in the mid range than at WOT.
    Thats why we run our shit at WOT all the time, saves fuel and is much more fun!! lol

    Travis

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    Quote Originally Posted by TwinTurbo540 View Post
    Thats why we run our shit at WOT all the time, saves fuel and is much more fun!! lol

    Travis
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    "SAE" states that it takes "1/2 lbs of gasoline per horsepower per hour at sea level to maintain a level of sustained power in a 4 stroke engine". I assume this statement is aimed at normally aspirated motors. I also assume that your particular "boost, intake temps, valve event timing, cylinder head temps, piston materal, oil temps, cylinder head configuration, egt's, along with fuel/air mixtures and type of fuel would also be areas to consider". Does your particular set up need 'more fuel for cooling' or does it run well on the lean side' ? (because you have exhaust cooling in your valve timing) This would be the larger question. Only you can answer your question, through testing.

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    Quote Originally Posted by VDRIVERACING View Post
    Anyone have a formula to determine fuel needed with specified HP for supercharged engine at a given ci and boost?
    I believe these guy's in this link will be able to help you out if you call them, Or maybe if you look over their web site long enough you might find some of the info in here. I believe I have seen some stuff like what you are looking for in here before, But Not 100% sure of it either, But it's worth a try anyway's. Good luck with it.

    http://www.holley.com/TechService/Library.asp

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    Quote Originally Posted by VDRIVERACING View Post
    Anyone have a formula to determine fuel needed with specified HP for supercharged engine at a given ci and boost?
    Ask Steel Comp the BSFC's of Nelsons engine, it might give you a baseline. I don't think you'll get a # for ci and boost limit. But a BSFC for a boosted engine at 800hp will calc out lbs per hour of fuel.

    Maybe Un-Changed (Mark) or Scott can give you a baseline.

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    gn7
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    Quote Originally Posted by VDRIVERACING View Post
    Anyone have a formula to determine fuel needed with specified HP for supercharged engine at a given ci and boost?
    Bill, this is a can of worms. Right off, you would need to know the compression ratio and the LSA of the cam. Blower motors are ugly animals when it comes to BSFC. A 7to1 motor can consume the same amount of fuel ( all else being equal) as a 11-1 motor. But the HP will definitely be different. The cam LSA is big also because it effects how much fuel gets tossed out the exhaust. Two motors can create 1000HP with totally different cams and have totally different BSFC. Doesn't make one more right than the other. I don't mind higher BSFC, (because race fuel is so damn cheap) but there are cases where they can actually be beneficial in a blower motor.



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    Quote Originally Posted by gn7 View Post
    Two motors can create 1000HP with totally different cams and have totally different BSFC. Doesn't make one more right than the other. I don't mind higher BSFC, (because race fuel is so damn cheap) but there are cases where they can actually be beneficial in a blower motor.
    All else being equal I'd take the more effecient one
    (lower BSFC)

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    One would think. But sometimes that is not always the smart thing to do. depending on the HP, and the duration you are going to run the thing flat footed, even best inconel valves will say enuff is enuff, if you don't throw some nice cool fuel across them. Good valves, coatings, cool head seats with with wide valve seats, and 3/8 stems and you can get away with quite a bit. The new LS9 motor has a LSA up around 120+ and electronic sequencial injection, and lives. I'd rather just buy fuel



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    Quote Originally Posted by gn7 View Post
    One would think. But sometimes that is not always the smart thing to do. depending on the HP, and the duration you are going to run the thing flat footed, even best inconel valves will say enuff is enuff, if you don't throw some nice cool fuel across them. Good valves, coatings, cool head seats with with wide valve seats, and 3/8 stems and you can get away with quite a bit. The new LS9 motor has a LSA up around 120+ and electronic sequencial injection, and lives. I'd rather just buy fuel
    Most certainly a point to look at. Lean is mean but 9 seconds isn't like 5 minutes or longer. Cool fuel is a good thing.

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    I think Bill is referring to designing his fuel system, not actual engine fuel flow data. 1/2 lb fuel per HP per hour should be safe for just about anything, but that's fuel delivery at the engine. You need to take into consideration fuel system inefficiencies to really have a working number for the fuel delivery system. 1200hp = 100gph at the engine. I'd double that, so at minimum I think a 200gph pump is what I'd use.
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    Steel has the idea. I have been running ~850 HP with a given fuel delivery setup, and am now building an engine with greater potential. Up to now I have been confident with the 140GPH mechanical pump and -10 lines to the regulator. The current setup has been superbly up to the task.

    I can't tell you the HP, because the engine is still under development...and becasue I wouldn't spill that anyway!!!!!

    I imagine the plumbing is still good, but wondering where that pump (Clay Smith) is gonna fall behind. I'm running 2-1150's on top but figure the cubic inch--460--and top rpm--7500--keep them in the game with a peak volume demand of 2000 CFM.

    I was looking more for rule of thumb type stuff.
    Last edited by VDRIVERACING; 09-28-2009 at 09:52 PM.

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