Bracket Talk
Return vs Bypass vs Deadhead

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July 23, 2025, 03:29 PM
BG7X77
Return vs Bypass vs Deadhead
Does anyone have any real world data on a return fuel regulator being more consistent than a dead head or more appropriately dead head with bypass at the pump. Deciding how to run a new fuel system.


BG
July 23, 2025, 04:00 PM
Goob
No I don't, but if I were starting with a clean sheet, I'd use a bypass style with return, at the carb / fuel rail.


"Despite the high cost of living, it remains popular."
Dave Cook
N375
July 23, 2025, 08:06 PM
rusty
quote:
No I don't, but if I were starting with a clean sheet, I'd use a bypass style with return, at the carb / fuel rail.

x2 with a good belt drive pump


honesty is the best policy,insanity is a better deffense
1.036, 6.16@ 224

July 23, 2025, 08:59 PM
markemark
quote:
Originally posted by rusty:
quote:
No I don't, but if I were starting with a clean sheet, I'd use a bypass style with return, at the carb / fuel rail.

x2 with a good belt drive pump


And front mounted fuel cell
July 23, 2025, 09:01 PM
Curly1
A return style regulator is only way to go. More consistent, much easier on pump and no worries of vapor locking.
With a return style regulator your fuel pressure and fuel temperature will be more consistent, your car will be more consistent and your pump will last longer because the fuel is not starting and stopping and pump is not going wide open against closed deadhead regulator. Your pump will draw less amps and run cooler.


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July 23, 2025, 11:29 PM
TOP38
You didn't provide more specific details on your combo,,, I have used a dead head regulator for ages with no issues. The pumps that require a bypass are equipped with them so why add more cost with more fuel lines and fittings for a bypass! This applies for electric fuel pumps only. Belt drives are a different story. Buy a got quality pump and regulator such as Product Engineering!
July 24, 2025, 07:56 AM
BG7X77
Back half door car, fuel cell in front isn't really feasible. Currently 650hp sbc, 150 billet holley, old style canister style filter and a mallory return style with #8 up and #8 return (not really ideal), regulator up front, no issues but going to upgrade. Several schools of thought better to have higher pressure up to regulator with bypass at pump in rear, or return style up front to keep fuel from sitting in lines. New motor is 845hp sbc, looking at magnafuel, weldon, product engineering as pump and regulator options. If I could go to a belt drive and fuel cell up front I likely would take that advice all day long, just dont think its really feasible with stock front end. If anyone has pictures of how they have done that I would love to see it.


BG
July 24, 2025, 07:59 AM
BG7X77
quote:
Originally posted by Curly1:
A return style regulator is only way to go. More consistent, much easier on pump and no worries of vapor locking.
With a return style regulator your fuel pressure and fuel temperature will be more consistent, your car will be more consistent and your pump will last longer because the fuel is not starting and stopping and pump is not going wide open against closed deadhead regulator. Your pump will draw less amps and run cooler.


Will still have any outlet to return fuel to tank, simply in rear. Would need to run a #10 return from front, which is doable, just considering options.


BG
July 24, 2025, 08:01 AM
BG7X77
quote:
Originally posted by TOP38:
You didn't provide more specific details on your combo,,, I have used a dead head regulator for ages with no issues. The pumps that require a bypass are equipped with them so why add more cost with more fuel lines and fittings for a bypass! This applies for electric fuel pumps only. Belt drives are a different story. Buy a got quality pump and regulator such as Product Engineering!

Product engineering is high on the list. I hear very good things.


BG
July 24, 2025, 09:30 AM
markemark
If new fuel system and also replacing fuel lines consider using PTFE. I just purchased transmission lines in 6AN, black plastic coated PTFE and crimp on ends installed. Slightly more expensive, but easier to run being smaller finished OD. I have fuel cells on both ends of my car and replacing the rear cell line with this same style PTFE.
July 24, 2025, 12:19 PM
rusty
build a cell to fit the space you have in front.i have done two or three times.


honesty is the best policy,insanity is a better deffense
1.036, 6.16@ 224

July 24, 2025, 12:24 PM
Goob
quote:
Originally posted by BG7X77:
quote:
Originally posted by Curly1:
A return style regulator is only way to go. More consistent, much easier on pump and no worries of vapor locking.
With a return style regulator your fuel pressure and fuel temperature will be more consistent, your car will be more consistent and your pump will last longer because the fuel is not starting and stopping and pump is not going wide open against closed deadhead regulator. Your pump will draw less amps and run cooler.


Will still have any outlet to return fuel to tank, simply in rear. Would need to run a #10 return from front, which is doable, just considering options.


-8 return line is larger than necessary, don't think you need more than the -8 to the regulator.
Remember that the larger the fuel line from the rear mount pump, the higher inertia weight (resistance) of the fuel column you're pushing forward.
I'm running 550-ish HP on a Holley Street/Strip block mount mechanical pump, no regulator or return.


"Despite the high cost of living, it remains popular."
Dave Cook
N375
July 24, 2025, 02:32 PM
BG7X77
Decided to go with a Product Engineering Pump/Filter/Return to tank coupled with their hi/lo bypass bleed system that also returns to the tank. Maintains high head pressure to front of the car, and allows constant fuel flow with bleed offs one on inlet side (0.058 jet) of regulator and one on the low pressure feed side (0.22 jet). Appreciate everyone's input.


BG
July 28, 2025, 04:32 PM
FootbrakeJim
I think you made a good choice. I plumbed mine with -8 from cell to regulator, and -10 return to cell.
That was based on Barry Grant's advice, and he really did figure out a lot of stuff before many others did. His thinking was the return needed to be larger than the supply, otherwise when demand drops sharply, (like when you pedal or lift), the regulator would not be able to control the fuel pressure if the return hose is the same size as supply or smaller, and already full of fuel at nearly pump pressure, so it would "spike" the pressure to the carb inlet and surge past the needle and seat, creating potential for a rich stumble if you whomped it.


Dan "Jim" Moore
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