100gph enough to support 500hp?
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BlueMonster65
Founding Member
should be good. 3/8" or -6an is good btwn 400 and 450hp NA. 500hp and you might want to consider -8an line. once you add a supercharger or turbo fuel pressure is as important as volume. so for example that pump wll need to be able to flow 100gph at 15psi if you want to run 10lbs of boost. but naturally aspirated you only need to make sure the pressure stays between 5 and 9psi.
Think about it, just how bad would your fuel mileage have to be to use a 100 gph fuel flow ? I was running a 30 gph pump with the 400 hp 5.0 in my Ranger and never came close to using it all. With a 30 gph flow, it would have to be getting worse than 2 mpg to use all the flow. Unless you're going to go with EFI, you don't need all that fuel with a carb setup. Those HV pumps are highly over rated for carbs.
The 100GPH pump will do it.allcarfan said:
The 3/8" feed line will work(I'm assuming you're carbureted with the mechanical fuel pump), but it's cutting it close. It would be much safer to install a 1/2" supply line from the fuel tank feeding the pump, when you consider acceleration forces, temperatures, etc encountered during driving conditions.
This is for an N/A motor right?
Yup...NA motor.
500hp might be pushing it a bit with my estimate, but I should be close. At least 450. Your assumption is also correct...carb'd engine with a mechanical fuel pump.
I know if I had an electric pump, I would need some kind of adjustalbe pressure regulator....do I need one of those with a mechanical pump?
500hp might be pushing it a bit with my estimate, but I should be close. At least 450. Your assumption is also correct...carb'd engine with a mechanical fuel pump.
I know if I had an electric pump, I would need some kind of adjustalbe pressure regulator....do I need one of those with a mechanical pump?
Only if it puts out greater than say about 8psi.
A good pump for that application would be the Holley 110GPH fuel pump.
It would do it with no regulator, and you can clock the housing to the desired position for line routing. Even with the 3/8" inlet fitting, if you feed it with a 1/2" line, it would supply enough.
There's other pumps that would do it also, such as the Edelbrock Performer fuel pump, but you can't clock the housing.
My problem always seems to be doing things twice. I'll get a fuel pump and it will work great, but then next year I'll have to upgrade to support more horsepower. But I suppose that's what Hot Rodding is about.
I'm getting better at planning for overkill now-a-days
A good pump for that application would be the Holley 110GPH fuel pump.
It would do it with no regulator, and you can clock the housing to the desired position for line routing. Even with the 3/8" inlet fitting, if you feed it with a 1/2" line, it would supply enough.
There's other pumps that would do it also, such as the Edelbrock Performer fuel pump, but you can't clock the housing.
My problem always seems to be doing things twice. I'll get a fuel pump and it will work great, but then next year I'll have to upgrade to support more horsepower. But I suppose that's what Hot Rodding is about.
I'm getting better at planning for overkill now-a-days
Hack
15 Year Member
I don't know anything about what fuel pump is needed, but the concern would be regarding the fuel consumption at an instant of time, with wide open throttle, at near maximum engine rpms. You really don't want the engine to go lean at that moment. The fuel mileage that generally can be calculated is an average which includes idling, cruising, etc. Therefore, the average fuel consumption per mile will be much less than the peak requirement of an engine.D.Hearne said:
I found a 6 inlet pump on ebay that is brand new for $50. It flows 100gph. I believe it is a carter. That is what I was going to go with.
Even at WOT on say a 12 second car, at 100gph, you're flowing 43 oz's of fuel in 12 seconds, with a carb, that amount of fuel isn't going to flow thru 4 tiny jets in a 4 bbl in 12 seconds, with only the engine's vacuum pulling on the fuel. I ran my 427 with 2x4 bbl Holleys with the stock fuel line that the car came with , may have been 3/8 line on a big block Stang, but could also have been 5/16, I can't recall. The fuel pump I used was a stock pump for a 427/428CJ motor. Never starved it for fuel, even at WOT. Don't know what the flow rating was on that pump, but it was likely less than 100 gph.Hack said:
Hack
15 Year Member
Ok, I had to try to calculate this out. 
Yes, I'm a geek, but I'm proud!
weight of a gallon of gas ~ 6 lbs
weight of a std cubic foot of air ~ 0.0807 lbs
stoichiometric a/f ratio is 14.7 lbs air/1 lb gasoline
For a 427 cubic inch engine ~ 0.247 cubic feet displacement
Pick 6,000 rpm as a redline. Each cylinder will be filled every other revolution, so halve the rpms to calculate fuel usage. At 100% volumetric efficiency (overestimate, counteracting the fact that you will want to run a little rich and have some safety margin) ~ 742 cubic feet of air consumed per minute = 44,490 cubic feet consumed per hour.
44,490 cubic feet of air per hour ~ 3590 lbs of air per hour.
divided by 14.7, that gives you ~ 244 lbs of gasoline per hour.
divided by 6 gives you 40 gallons per hour.
So if a 100 gph fuel pump can actually deliver 100 gph, it looks like overkill for many applications. I'm forced to agree with D. Hearne. Seems like a good place for me to be.
Yes, I'm a geek, but I'm proud!weight of a gallon of gas ~ 6 lbs
weight of a std cubic foot of air ~ 0.0807 lbs
stoichiometric a/f ratio is 14.7 lbs air/1 lb gasoline
For a 427 cubic inch engine ~ 0.247 cubic feet displacement
Pick 6,000 rpm as a redline. Each cylinder will be filled every other revolution, so halve the rpms to calculate fuel usage. At 100% volumetric efficiency (overestimate, counteracting the fact that you will want to run a little rich and have some safety margin) ~ 742 cubic feet of air consumed per minute = 44,490 cubic feet consumed per hour.
44,490 cubic feet of air per hour ~ 3590 lbs of air per hour.
divided by 14.7, that gives you ~ 244 lbs of gasoline per hour.
divided by 6 gives you 40 gallons per hour.
So if a 100 gph fuel pump can actually deliver 100 gph, it looks like overkill for many applications. I'm forced to agree with D. Hearne.
Seems like a good place for me to be.
Hack
15 Year Member
I'd better try to complete the mathematical analysis. To answer the question: will a 100 gph fuel pump support 500 horses? I'm quoting numbers from quick internet searches in this and my above post, so please correct me if something's wrong. My math also isn't always the best!
Gasoline has about 115,000 btu/gallon energy content
2,545 btu/hour = 1 horsepower
Gasoline engines have about 0.26 - 0.34 thermal efficiency
So 500 hp = 2,545x500 = 1,272,500 btu/hour
1,272,500 btu/hour divided by 115,000 btu/gallon = 11 gallons/hour
If the engine has 0.3 thermal efficiency, roughly 37 gallons/hour would be required for 500 horsepower.
Like I said, please have a look and correct any glaring errors!
Gasoline has about 115,000 btu/gallon energy content
2,545 btu/hour = 1 horsepower
Gasoline engines have about 0.26 - 0.34 thermal efficiency
So 500 hp = 2,545x500 = 1,272,500 btu/hour
1,272,500 btu/hour divided by 115,000 btu/gallon = 11 gallons/hour
If the engine has 0.3 thermal efficiency, roughly 37 gallons/hour would be required for 500 horsepower.
Like I said, please have a look and correct any glaring errors!
Red Barchetta
Founding Member
I couldn't tell you how many times I've posted this link to Century Performance on different forums (including this one) but it's a must read:allcarfan said:
Fuelish Tendencies
They talk about electric fuel pumps, but gph is gph so check it out and make your decision accordingly.
Another way to figure it.....
A typical naturally aspirated engine has a Brake Specific Fuel Consumption (BSFC) of between .4 and .6 lbs/hp/hr, so a 500 hp engine would consume between 200 and 300lbs per hour at max power. A blown engine would have a BSFC of .65 to .68, with a requirement up to 340 lbs/hr at maax power.
Gasoline typically weighs between 6.1 and 6.5 lbs per gallon. Your fuel requirement lies between 30.76 and 49.18 gph at max power, naturally aspirated, and as much as 55.73 gph for a blown engine.
Add 25% for overkill and make sure the pressure meets your requirement. Soundsl like that pump meets the need.
A typical naturally aspirated engine has a Brake Specific Fuel Consumption (BSFC) of between .4 and .6 lbs/hp/hr, so a 500 hp engine would consume between 200 and 300lbs per hour at max power. A blown engine would have a BSFC of .65 to .68, with a requirement up to 340 lbs/hr at maax power.
Gasoline typically weighs between 6.1 and 6.5 lbs per gallon. Your fuel requirement lies between 30.76 and 49.18 gph at max power, naturally aspirated, and as much as 55.73 gph for a blown engine.
Add 25% for overkill and make sure the pressure meets your requirement. Soundsl like that pump meets the need.
Red,
Thanks for the site. I put it in my favorites. I am not sure how accurate it is though. 3/8" line good to 375 hp?
I think the 3/8" line and the 100gph pump will work. However, I am going to braze a 3/8" and 1/2" hard line about 3" long into my gas tank and plug them both. I will leave them plugged in case I want to upgrade to an electric pump later on and run a return line.
thanks everyone. Hopefully i wont have a problem with the 3/8" line and 100gph pump. I will keep an eye on my air/fuel gauge and my fuel pressure guage.
Thanks for the site. I put it in my favorites. I am not sure how accurate it is though. 3/8" line good to 375 hp?
I think the 3/8" line and the 100gph pump will work. However, I am going to braze a 3/8" and 1/2" hard line about 3" long into my gas tank and plug them both. I will leave them plugged in case I want to upgrade to an electric pump later on and run a return line.
thanks everyone. Hopefully i wont have a problem with the 3/8" line and 100gph pump. I will keep an eye on my air/fuel gauge and my fuel pressure guage.
Hack said:Ok, I had to try to calculate this out.
weight of a gallon of gas ~ 6 lbs
weight of a std cubic foot of air ~ 0.0807 lbs
stoichiometric a/f ratio is 14.7 lbs air/1 lb gasoline
For a 427 cubic inch engine ~ 0.247 cubic feet displacement
Pick 6,000 rpm as a redline. Each cylinder will be filled every other revolution, so halve the rpms to calculate fuel usage. At 100% volumetric efficiency (overestimate, counteracting the fact that you will want to run a little rich and have some safety margin) ~ 742 cubic feet of air consumed per minute = 44,490 cubic feet consumed per hour.
44,490 cubic feet of air per hour ~ 3590 lbs of air per hour.
divided by 14.7, that gives you ~ 244 lbs of gasoline per hour.
divided by 6 gives you 40 gallons per hour.
So if a 100 gph fuel pump can actually deliver 100 gph, it looks like overkill for many applications. I'm forced to agree with D. Hearne.
My God I've created a monster 
Glad you math is better than mine. 
BullittStangV8
Founding Member
im still having a little trouble figuring this of this out. That sites calculations would tell me that i would need between 95-102 gph for my create engine 5.0 with GT-40 heads. With my headers and such, im expectign around 350 hp, but i want to be able to expand it. So going with 400 hp, i would need 92-102 gph. So would i need a pump that flows 100 or so gph? Would my gas milage be horrible? and ill be going with a mechanical pump i guess, so would this one be a good choice? http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=1462&prmenbr=361
Mike
Mike
not sure if you are interested, but there is a guy on ebay that sells new Carter 100gph fuel pumps for $50. They are also chrome.
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