Fuel plumbing for an FE

[Anthony]

Dan,

as cross sectional area determines max flow capabilities, the cross sectional area of a circle is pie*r*r, or pie*d*d/4. So, if I have a 2" ID pipe, the cross sectional area would be 3.141 sq inches. If I have a pipe twice in diameter, 4 inches, then the cross sectional area is 12.564 sq inches, 4 X as much. Therefore a 6AN hose has a 3/8" ID, and a 12AN hose, twice the diameter, has a 3/4" ID, the 12AN hose has 4X the cross sectional area, more area for fluid to flow, and should flow about 4X as much as a single 6AN. So, it would take 4 6AN lines to flow about as much as a single 12AN line. However, what you said before is correct as well, in that wall resistance does come into play, and if the cross sectional areas of 4 6AN lines and a single 12AN line are exactly the same, the 12 AN line would flow a little more than the 4 6AN lines due to wall resistance, and would be variable from 1% to 10, 20, 30% dependent upon on the flow rate and viscosity of the fluid, with higher flow rates and higher viscosity fluids having a greater loss to resistance in the 4 6AN lines, and a greater diofference comparing it to the single 12AN line.

Not to open another can of worms, but this also has ramifications in cylinder port design, not that I'm any expert on the subject, but I do like the theory. With an exhaust port, which is purely hot gas, I would think you would want round exhaust ports as an optimal design, with less wall-gas injterface not only for flow resistance , but also less heat transfer. However, you also don;t want a sharp bend in the short side radius, so you may want to raise the floor alittle, blunting the bottom of the circle, to enhance flow in the bottom of the port. With the intake port, it is more complex, as you have a mixture of air and liquid/vapor fuel. You may want more of a square port than a round port, utilizing a flat bottom, for more wall space for fuel to be vaporized, so a round port on the intake side may not be optimal even though a round port is optimal for flow alone, with again taking in consifderation of the short side radius of the port.

As I have found out many times, things are usually alot more complicated than what they appear to be in the first place.

[shelby racer]

Thanks for all the input. Maybe I can make this question a little easier. My csx4750 series came plumbed from the factory with two fuel pumps in the trunk running (2) -6 lines into the engine compartment. I planned on running them into a junction block, into a Holley fuel pressure regulator, into a large summit fuel filter into -8 aeroquip line to a single Holley 4150hp 750cfm double pumper with an aeroquip -8 fuel log and measuring fuel pressure off the other end (after it feeds the carb) on a 1965 427 (30 over) side oiler with edlebrock aluminum heads (Intake = 2.19, exhaust=2.09) rated at ~525 gross / crankshaft hp. Does anyone have actual experience with a similar set up and will it be adequate for a spiritedly driven street car (I already have enough racing mustangs for the track). The car is already plumbed this way, but I am still struggling with getting it finished and running, so I can still change it if I have to, but I don't want to have to replumb it. Thanks again.
John(;-)

[Anthony]

Originally Posted by shelby racer

My csx4750 series came plumbed from the factory with two fuel pumps in the trunk running (2) -6 lines into the engine compartment. I planned on running them into a junction block, into a Holley fuel pressure regulator, into a large summit fuel filter into -8 aeroquip line to a single Holley 4150hp 750cfm double pumper with an aeroquip -8 fuel log and measuring fuel pressure off the other end (after it feeds the carb) on a 1965 427 (30 over) side oiler with edlebrock aluminum heads (Intake = 2.19, exhaust=2.09) rated at ~525 gross / crankshaft hp. Does anyone have actual experience with a similar set up and will it be adequate for a spiritedly driven street car (I already have enough racing mustangs for the track).

That's kind of the way my car is. It should be fine. I have both electric pumps pumping through the same 6AN line, then a suction 6AN line to my mechanical pump, with its outflow to a junction block with the 6AN line from the electric pumps, and out from the junction block with a 8AN line. Should be fine.

[RedCSX1]

Originally Posted by shelby racer

1965 427 (30 over) side oiler with edlebrock aluminum heads (Intake = 2.19, exhaust=2.09) rated at ~525 gross / crankshaft hp. John(;-)

John, Did you get the email I sent you about the headers?

Who picked the 2.09 size exhaus valves Mighty large, see it hurting overall performance.

Morgan

[shelby racer]

Thanks Morgan,
Shelby is sending me a replacment aprt which should fit better. Oddly they don't know why the spec on the # 5 tube is to go between the steering shaft and the support, but I think it has something to do with authenticity..
John(;-)

[Carnut427]

Originally Posted by Anthony

Dan,

as cross sectional area determines max flow capabilities, the cross sectional area of a circle is pie*r*r, or pie*d*d/4. So, if I have a 2" ID pipe, the cross sectional area would be 3.141 sq inches. If I have a pipe twice in diameter, 4 inches, then the cross sectional area is 12.564 sq inches, 4 X as much. Therefore a 6AN hose has a 3/8" ID, and a 12AN hose, twice the diameter, has a 3/4" ID, the 12AN hose has 4X the cross sectional area, more area for fluid to flow, and should flow about 4X as much as a single 6AN. So, it would take 4 6AN lines to flow about as much as a single 12AN line...

As I have found out many times, things are usually alot more complicated than what they appear to be in the first place.

I stand corrected. Although I was a machinist and not an engineer, I did some research once at work concerning flow in steel pipe, and found the same info you report, that when you double the size you quadruple the flow, although for some reason I thought it only applied to steel piple, where a 1" pipe is actually a nominal sizing, and didn't realize it applied to tubing or -AN sizes as well. Thanks for the info, I'll reconfigure the info in my memory bank. BTW, I also found that one 90* bend creates as much resistance as 8' of straight pipe. We were having problems getting enough oil flow in some machinery, causing premature bearing failures.
By the way, the car still runs great...going back to my original rule of thumb of one 3/8" fuel line will support 400 hp, my two 3/8" lines are still good for 800 hp, although, thanks to you, I'm beginning to have doubts about that too...

Dan