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Author
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Topic: How much fuel?
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 04-02-2002 08:50 PM
   
How much gasoline does a 400+ci 500+ h.p. 850cfm dp'r 10-11 second 3000# car burn in a 1/4mile? Not counting the burnout or staging, just during the 10-11 second wide open blast. 10 oz., 1/2 gal, or what?SteveW
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F551
Gearhead Posts: 266
From: Manitoba, Canada
Registered: Nov 2000
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posted 04-02-2002 09:14 PM
My 500cid 650 hp 800cfm dp'r 10.5 second 3200# car uses 3/4 of a gallon from leaving the pits to returning after the pass.So probably 1/2 gallon seems right from my experience. I top the cell after every pass
(part of my ritual), only variance would be due to cool weather - longer warmup.  ------------------
Fred
68 Mustang 500CID/Powerglide - "No Tubs"
86 Mustang GT Cobra
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chips67
Gearhead Posts: 663
From: louisville, ky, usa
Registered: Jul 2001
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posted 04-02-2002 10:37 PM
steve, good subject. i was in a talk with a local road racer who races his shelby mustangs across the country and runs his own classic mustang junkyark. i asked him if he had a 3/8 pickup/sending unit for my car. he said i didnt need it because he runs an original 5/16 line and his shelby sustains speeds over 150 mph. i got to thinking later, doesnt a car use a LOT more fuel under hard acceleration than at a sustained rate of speed? maybe thats why you get better gas mileage on the highway than the city! i wanted to call the guy back but i might need a part someday and he'll remember me. ever notice how you always think of stuff AFTER the conversation is over? he is also the guy who quit drag racing because its so boring and the big money always wins. meanwhile he's out west trying to get another carroll shelby autograph and kiss saleens butt at these races for perfectly restored vintage sports cars ....YAWN! and when he DID drag race 20 years ago his car was one second quicker than whatever your new best et is. anyway...always good to flame somebody behind their back who really deserves it. what a dilweed. now im sure im buying 1/2 inch fuel line.------------------
67 coupe, 650dp and rpm intake on 5.0 with afr 165 heads, 4 speed, 4.11's.....best so far is [email protected] in 1/8 mile with 1.79 60ft. time.
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 04-02-2002 11:14 PM
Thanks Fred and Chip,I'm really hoping someone can answer this mystery for us. Maybe someone that has measured fuel usage through a 11 second dyno pull.
Or someone that can calculate how much gas goes into 850 cfm of air for a 13-1 air-fuel ratio in 10 seconds? The reason I'd like to know of course is to find how many gph my fuel system must be capable of.  SteveW
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TomP
Gearhead Posts: 6120
From: Delta BC Canada
Registered: Dec 99
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posted 04-03-2002 04:35 AM
less than a gallon.Mine uses 3/4 of a gallon or so, when you consider the total "trip" distance the gas mileage is poor, less than 2mpg in stop and go driving  ... or course your mileage may vary 
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Larry Jennings
Gearhead Posts: 540
From: Redwood City, Ca. USA
Registered: Apr 2000
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posted 04-03-2002 04:36 AM
I favor going way overboard on fuel systems, as the Rs go up and down through a pass the fuel use varies, having an overkill system assures you'll meet the engines highest demand.
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clevelandstyle
Gearhead Posts: 1309
From: central Indiana
Registered: Jul 2001
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posted 04-03-2002 08:55 PM
Try this. I don't know if it's what you're looking for, but it may help.http://www.prestage.com/carmath/calc_fuel.asp Remember, this calculation will be a minimum requirement. ------------------
Ben
Grabber Green '70 Mach I 351C 4V
Robbin Egg Blue '79 Fairmont 351C 4V
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 04-03-2002 09:48 PM
Ben,Thanks!! It says that 550 hp needs 46 gph. On the current (new) fuel system which is 3/8" s/s tubing from the tank to the mechanical pump with a holley red in the rear, and without the mechanical, it'll pump a gallon per minute (60 gph). It'll pump even more with the mechanical pump and the engine turning 4500-6500 rpm. The old fuel system only had 5/16" line and 1/4" fittings on the Holley red pump and kept up with a 12 flat engine. We'll see, if it lays down through the traps I'll up size the pump/pumps. Thanks again! SteveW
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chips67
Gearhead Posts: 663
From: louisville, ky, usa
Registered: Jul 2001
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posted 04-03-2002 09:52 PM
wow, if that formula is right i only need 38 gph max! of course i dont like it and heres why...if i was road racing it works better. i dont think it takes into account the load placed on the motor in drag racing....or does it?------------------
67 coupe, 650dp and rpm intake on 5.0 with afr 165 heads, 4 speed, 4.11's.....best so far is [email protected] in 1/8 mile with 1.79 60ft. time.
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clevelandstyle
Gearhead Posts: 1309
From: central Indiana
Registered: Jul 2001
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posted 04-03-2002 10:00 PM
Steve,
I'm glad this helped. I also believe in the "bigger is better" rule on fuel systems. ------------------
Ben
Grabber Green '70 Mach I 351C 4V
Robbin Egg Blue '79 Fairmont 351C 4V
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 04-03-2002 10:12 PM
Ben,I agree, but we've also seen examples of huge overkill with fuel systems that cause all kinds of problems like deadheading the pump and over powering needle valves. Not to mention using money that could be spent on go fast parts. SteveW
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Butch Jennings
Gearhead Posts: 633
From: No. California
Registered: Apr 2000
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posted 04-03-2002 10:17 PM
None of that takes into consideration the amount of g force that the fuel system has to overcome on a hard running car. The larger the fuel line and the harder the car runs puts all of those formulas further out of whack. But then, I'm with Larry on the overkill deal....I'd never short change my fuel system. I run a 400 gph pump with a -10 line to the front and a -8 return line to run my motor and fogger.------------------
Butch
460 powered 1967 Comet Cyclone
10.271 @ 130.069
Butcher's Home Page
"Friends don't let friends drive Chevys"
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 04-03-2002 10:59 PM
Butch,No disrespect here. How big is the ID of -10? I know your fuel system is good for 800+hp and it should be way overkill if someone is gonna run N2O I understand the big fuel systems if you're gonna run alcohol, you need 2.5 times more alcohol than gasoline, and that is usually when the BIG 400 gph systems and 1/2" lines come in real handy.
SteveW
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Butch Jennings
Gearhead Posts: 633
From: No. California
Registered: Apr 2000
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posted 04-03-2002 11:05 PM
quote:
Originally posted by steve'66:
Butch,How big is the ID of -10?
SteveW
It's not quite 5/8", closer to 9/16", if I had to do it over again I'd use a 5/8" hard line....that stuff wasn't readily available in aluminum (like it is now) when I did the car. That would be MUCH cheaper than a -10 hose front to rear  ------------------
Butch
460 powered 1967 Comet Cyclone
10.271 @ 130.069
Butcher's Home Page
"Friends don't let friends drive Chevys"
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jsracingbbf
Gearhead Posts: 2954
From: Batesville,MS. , U.S.A.
Registered: Mar 2002
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posted 04-04-2002 12:13 AM
I bet this won't help but here goes, I tune my car by the EGT reading AND how much fuel it burns in an 1/8th mile pass. When it is running close to the proper exhaust gas temp ( 1125-1150 ) it burns approx. 1 gallon to 1 1/4 gallons of methanol, depending on the track. I haven't noticed that much difference in air temps affecting this, although I'm sure it does somewhat. Alky is supposedly less affected by air temp.
Car is a enderle hat ( birdcatcher ) injected 514 motor.
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jsracingbbf
Gearhead Posts: 2954
From: Batesville,MS. , U.S.A.
Registered: Mar 2002
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posted 04-04-2002 12:27 AM
I forgot to mention this. I run a 3 gallon fuel cell up front. From there it feeds a hilborn #0 size belt drive pump. I can't remeber which size AN line feeds the pump but I think it is a # 10. After the pump the AN line goes down one size. the line is plenty big enough and thats how I prefer it. Why wouldn't a bigger line be better if you have to run a new one anyway? Looks like cheap insurnace to me. just my 2 cents
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Larry Jennings
Gearhead Posts: 540
From: Redwood City, Ca. USA
Registered: Apr 2000
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posted 04-04-2002 01:15 AM
While we're takin turns kickin ya. I've tried the mechanical with electric pump deal and while it increases pressure, it reduces flow. It's very like the series vs paralel electricity event. If I were doing your car I'd run a 1/2 line from about a 240GPH pump with a bypassing regulator and use the old 5/16 as the return plumbed in at the drain or neck of the tank . ------------------
If at first you don't suceed, sky diving is not the sport for you.
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