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Lots of people claim too big of a main feed line can be detrimental. More mass of fuel and a larger cross sectional area in the line for the G forces to act on.

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those people are flat wrong and don't understand the mechanics of fluids. the diameter of the line has no impact on the force imparted by acceleration, the effective length of the line does. the pressure exerted on a column of fluid would be SG (specific gravity) x .433 (PSI exerted by a 12" column of water) x distance from suction to feed x G force. the actual length of the line to some extent doesn't matter. an example would be say you have 15' of hose but 5' is taken up in bends. then the effective length would be 10'. so .725 x .433 x 10' x (say 2G) = 6.28 PSI. this is the pressure the pump would have to overcome to move fluid and is part of the reason to mount the regulator at the engine. most (decent) pumps have the ability to generate a fair bit, probably upwards of 20 PSI or so. i would say the VAST majority of our cars don't pull 2G for any length of time if at all. a TF dragster pulls around 4 off the line but actually pulls harder down track.

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Good points james.
I would think that the most it would do would slow down for a split second, and then this would never effect total amount delivered, let alone effect the generous amount of fuel supply in the fuel bowls, thats waiting to be emulsified.

If you want to worry about loss, look into the amount of friction loss in 90° bends...I forget the amount of loss occurred through that one 90° that can never be gained no matter what size line it runs to...its like 1800+ or something...crazy..

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9 sec et requires 180 gph , 8 sec et 240 gph

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9 sec et requires 180 gph , 8 sec et 240 gph

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i don't know where these numbers come from.


a general rule of thumb is .5 PPH (pounds per hour) per horsepower. as mentioned the SG of race fuel is around .725. a gallon of water (SG of 1) weighs around 8.35 pounds. 8.35 x .725 = 6.05. so a gallon of race fuel is about 6 pounds. an 800 HP engine will need about 400 PPH of fuel. 400 divided by 6.05 = 66.11 gallons per hour for 800 HP. an actual 180 GPH of fuel will feed 2000 HP.

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The SAE standard on fuel (gasoline) consumption is based on steady state operation, not acceleration of the motor like drag racing, I believe The thing I come back to on fuel delivery(volume) on drag race cars with catburetors is that you don't have enough fuel delivery if you can't richen the mixture up enough to slow the MPH down in the 1/4. We tend to forget that where trying to force (push) fuel thru a .120 size needle and seats, if we buy the good racing size needles and seats Any one ever try to do a fuel flow tests thru the needles and seats into a can I have That is the main reason I recommend using a way bigger fuel delivery system than most people do

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9 sec et requires 180 gph , 8 sec et 240 gph

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i don't know where these numbers come from.


a general rule of thumb is .5 PPH (pounds per hour) per horsepower. as mentioned the SG of race fuel is around .725. a gallon of water (SG of 1) weighs around 8.35 pounds. 8.35 x .725 = 6.05. so a gallon of race fuel is about 6 pounds. an 800 HP engine will need about 400 PPH of fuel. 400 divided by 6.05 = 66.11 gallons per hour for 800 HP. an actual 180 GPH of fuel will feed 2000 HP.

on another note let's face it racers are in love with their fuel systems. big manly pumps, -12 lines, half a dozen regulators...all trying to jam fuel through two (or four for dual carbs) .110" orifices, THAT'S where the restriction is the needle and seat.

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Line size/volume, pressure , restrictions.........all come into play , might dig the mechanal fuel pump out that delivers 80 gph , should be enough to feed the 600" .

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Line size/volume, pressure , restrictions.........all come into play , might dig the mechanal fuel pump out that delivers 80 gph , should be enough to feed the 600" .

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Line size/volume, pressure , restrictions.........all come into play , might dig the mechanal fuel pump out that delivers 80 gph , should be enough to feed the 600" .

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i'm fully aware of friction losses etc. i've been pumping oil for the past 15 years. IIRC Dwayne Porter's Satellite (3800#?) ran low 11's with a stock fuel system as in 5/16" line and mechanical pump. Ken Bowers runs a holley blue on his 150+ MPH 500" B1 SST Cuda. but i guess these guys don't know what they're doing.

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Been in the plumbing & heating industry for 35 years , if you read my post you will notice i mentioned guys going overkill with their fuel systems.

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Im just wondering if -10 is overkill..I have a long section of -8AN hose and some fittings. I know on the dragster I ran -8AN running alky/methonal and it was what I would consider a pretty high demand system...it burnt 2 1/2 gallons of fuel per 8th mile run.

So how does one draw the line? Does duel carbs make a diff?

According to BG the 280 Pump doesnt require a return, which is fine by me. It says a -10 to from the fuel cell to the inlet of the pump, then -8 to the regulator..
I have the pump and there two port regulator, I wont be running there fuel filter..I will be running a earls 85 micron stainless mesh type filter.

http://www.barrygrant.com/bgfuel/default.aspx?page=85

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This is BG 280 fuel pump by the way and needs to feed 800+hp..

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Some of those guys think they are feeding 2000 hp, not 800.

I really prefer hard line from the pump to the front. It has a larger inside diameter and less pressure drop due to curves in the hose.

Bob, I believe #8 line from the pump to the front (regulator) will be just fine. I do agree a return system is better than a dead-head at the regulator. When I used a carb, I ran two #8 lines from the cell to the filter/pump (Y-connection to solid line at inlet). But a #10 should be fine.

I also think putting #10 to the front is fine, just cost more and no benefit, at 800 hp.