lincolnlocker
Well-known member
Im willing to bet his fuel pump requires a 5/8 feed.... hence the reason he is so adamant on his fitting choice.
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Obs 38 gallon rear tank.
- Thread starter lildiup
- Start date
Im willing to bet his fuel pump requires a 5/8 feed.... hence the reason he is so adamant on his fitting choice.
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Strokersace
Well-known member
What Jake said!
old man dave
New member
I believe there's at least one pump maker that requires AN-10 or equivalent suction side or your warranty is toast.
Another reason is pumps don't do a good job of sucking fuel but they push very well. There is only 14.7 pounds (atmospheric) pressure pushing the fuel towards the pump. So, a reduction (larger hose) of hose sidewall friction (drag) allows the fuel to move more freely towards the fuel pump from the tank.
Its the same reason well pumps cannot lift water more than 34 feet without a booster venturi (jet) or having the pump located at the bottom of the well no matter how many horsepower the pump motor has. The atmosphere is only pushing so hard at 14.7 pounds or 34 feet water column pressure.
And there is the matter of the g-forces (inertia) making it harder for the fuel to flow towards the pump under acceleration. Assuming the pump is forward of the tank.
Where I worked municipal water systems, we had wells drawing at the 400' level with the multistage centrifugal pump mounted 400' down with the motor located topside in the pump house. That's right, a 400 foot driveshaft with a 350 horsepower motor at one end, pump at the other end.
Its basic high school Physics.
But its your fuel system, do what you feel like.
Another reason is pumps don't do a good job of sucking fuel but they push very well. There is only 14.7 pounds (atmospheric) pressure pushing the fuel towards the pump. So, a reduction (larger hose) of hose sidewall friction (drag) allows the fuel to move more freely towards the fuel pump from the tank.
Its the same reason well pumps cannot lift water more than 34 feet without a booster venturi (jet) or having the pump located at the bottom of the well no matter how many horsepower the pump motor has. The atmosphere is only pushing so hard at 14.7 pounds or 34 feet water column pressure.
And there is the matter of the g-forces (inertia) making it harder for the fuel to flow towards the pump under acceleration. Assuming the pump is forward of the tank.
Where I worked municipal water systems, we had wells drawing at the 400' level with the multistage centrifugal pump mounted 400' down with the motor located topside in the pump house. That's right, a 400 foot driveshaft with a 350 horsepower motor at one end, pump at the other end.
Its basic high school Physics.
But its your fuel system, do what you feel like.
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old man dave
New member
This is sorta correct, you are ignoring flow drag of fluids moving in a duct. Fluid near a duct wall is almost not moving, the fluid flow is only near the center of the duct only. So, real gains due to increased duct size is more than what the ratio of squares indicate. Drag surface varies by the increase in circumference, a linear function, the area with flow increases by the square.
Picture a (as an example only) dead flow thickness of 1/32" in the tube. The area of dead flow increases linearly (C=pi xD)as the duct size goes up, the area of actual flow increases by the square (piR squared), the thickness of dead flow doesn't change much if at all with a duct size increase.
You do the math. Actual flow increase is better than what your example says.
opcorn:
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Krause
New member
This is sorta correct, you are ignoring flow drag of fluids moving in a duct. Fluid near a duct wall is almost not moving, the fluid flow is only near the center of the duct only. So, real gains due to increased duct size is more than what the ratio of squares indicate. Drag surface varies by the increase in circumference, a linear function, the area with flow increases by the square.
Picture a (as an example only) dead flow thickness of 1/32" in the tube. The area of dead flow increases linearly (C=pi xD)as the duct size goes up, the area of actual flow increases by the square (piR squared), the thickness of dead flow doesn't change much if at all with a duct size increase.
You do the math. Actual flow increase is better than what your example says.
Correct, drag will be linear while volume is not, as you said this only drives home the point but I didnt want to get too physics-y all in one post. Nevertheless, Strokersauce you have a 5/8's pump so it is what it is haha, that thing must be a monster!
FrankTheTank
Active member
If your so adiment on a 1/2npt fitting, why not just use an equivlant size bulkhead fitting in the tank instead of a sump
old man dave
New member
AN-10 fitting is just about the same size as 1/2NPT but may need machining of the nut section to fit the sump.
97powerstroke
New member
Is anybody putting baffles in their tanks to get the full use out of the sumps?
lincolnlocker
Well-known member
lincolnlocker
Well-known member
Why not just make your own sump.?.. start with a big washer and step it down till the hole is the size of a bulkhead fitting. weld each washer in place. Drop the tank and weld it on the tank..
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Strokersace
Well-known member
I could and may. But like the cleanliness of the sump. Plus a larger cavity to draw from on the sump. And not really too keen on welding washer spacers to the bottom of the tank (to do it right anyway). I just find it funny that sump makers and others here are saying that 1/2" npt or 5/8" hose is way overkill when fuel pump manufacturers like aeromotive and fuelab require 5/8" on the thank side or warranty is void?!?! Sure the size may be plenty big but I'd rather have a warranty.
lincolnlocker
Well-known member
I dont blame you one bit bud! I was just throwing out sugjestions. Its a steel tank. If you can tig weld or know someone who can then I dont see why it couldn't be done in nice neet fashion?
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Krause
New member
I didnt realize you had to to get a warranty, in that case go nuts as I would as well! But 5/8 is nevertheless still way overkill.
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lincolnlocker
Well-known member
Even if one wasn't worried about the warranty, its not overkill on a pump of that caliber, or any pump for that matter.
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FrankTheTank
Active member
If you are willing to weld on the tank, here are your 1/2" npt fittings
Krause
New member
Thats correct, but the pump is overkill then. I can see 1/2, and to each their own on if someone wants to (or in this case needs to) use 5/8. But... 5/8 line will flow way more fuel that you could ever hope to pass through the two fuel rails, let alone pass through injectors (regardless of how big). I wont speculate how fast it would happen cause im only guessing, but a pump this size at 60 psi would empty 100 liters of fuel in like a minute (thats a guess). Point is, wide open, going up a hill, with a load, agaisnt wind, with huge injectors etc etc, it's just never gonna suck the tank dry as fast as a 5/8's system could. Its just a huge mismatch. Like I said to each their own, but we are talking around capacity to empty the tank faster than you filled it up at the pump, the motor could never use that.
lincolnlocker
Well-known member
Its not really the point on the pressure side.. its only on the tank side where it needs the large lines for the ease of pulling the fuel.. pressure side can be whatever size you feel like running since the inlet to the heads are 1/8 npt...as long as pressure stays identical before and after the heads. That way you know that there is zero pressure drop to the injectors.
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Krause
New member
Yep, hopefully you find something that fits your liking Strokersauce, that aeromotive pump must be a thing of beauty! (And please lets not hear of a hose get snagged off in front of that thing somehow :jawdrop: haha)
old man dave
New member
My fuel inlets are 3/8" ID feeding through the back of the heads with sweep bend fittings....And probably the same for StrokerAce.:hammer:
And pumps are rated in liters/gallons per hour, nowhere's close to 100 liters per minute. 26 gallons per minute would mean the pump empties out a tank in 44 seconds, ain't happening with any automotive based fuel pump unless you commute with a top fuel dragster (8000hp takes a lot of nitro at the rate of about 225 liters per minute or one gallon per second).
For reference, the stock pump is supposed to pump 19gph or 71 liters per hour.
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lincolnlocker
Well-known member
Guess I shoul have said, unless customized, lol...
Ill take a pm on how you did the 3/8s id feed port that was ment for banjo bolts.. did you machine the head to except bigger fittings cuz I dont think the port is 3/8 diameter to begin with.
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