Return line fuel system?

Posted By: SLOW67

Re: Return line fuel system? - 11/28/13 02:43 AM

Quote:

Quote:

In a returnless system I understand that fuel is warmer when it gets to the carb as opposed to a return system. My question is how much of a difference does it really make? I am preparing to make my fuel system NHRA approved and I can save alot of money putting my reg. in the trunk with the pump and tank and just running my low pressure side to the front of the car. Will there really be that much of a difference on a street/strip car?

This is at least the 2nd time in two post that you used the terms "cheap" and sometimes it works but generally it doesn`t........just check out past posts about dampners, heads pumps etc. Don`t cheap out on the fuel system or it will bite you in the azz............

I understand what your saying, but I don't have much if any of a budget sometimes and I've literally built this car myself with the cheapest speed parts I can find and none have let me down yet. In over 2 years I've put close to 20k miles on this setup that was built entirely from chinese ebay parts and the only part to let me down has been the head gaskets, one of which was the original from 1976.

I like the idea of running one less line to the front for two reasons, one CHEAP and two, anywhere I can simplify or make a system more modular I will do it. If I only have one line to the front of the car it will make it so my pump, reg., and tank are all in one place. Easier to start looking for problems if one arose, and makes for a simple install.

Posted By: MR_P_BODY

Re: Return line fuel system? - 11/28/13 03:15 AM

Your gonna do what you want... but in my opinion a
return is a much better set up.. but what do I know..
I didnt stay in a Holiday Inn.. but I did work in the
fuel lab for 30+ years... when we started with perf
or injected we ran a return line... some time later
we dropped it... for 1 reason.. repeat.. 1 reason ONLY
and that was cost... but the company will do anything
to cut cost... but I also understand a budget... but
also sometimes you need to save a bit more before
you jump........... JMO

Posted By: Cab_Burge

Re: Return line fuel system? - 11/28/13 03:17 AM

I used a Magnafuel 275 pump on my street and strip Duster, it was a learning experience getting the fuel delivery system where it was relaible and trouble free

Magnafuel wanted a inline fuel filter between the pump and the tank with a 80 Micron or larger filter, follow thier instruction on that

I didn't, at first

I did use the size of lines they wanted and once I put a 80 micron filter in the feed line, instead of a 10 micron paper element filter, the car started responding to jet changes at WOT

I didn't want to run a return line from the front of the car back to the stock tank, with the Magnafuel pump mounted behind and the bottom fuel entrance below the sump on the stock tank I never had a problem with hot fuel, that I know of. I ended up putting a dual sensor wide band unit on the car to help me tune the six pak on it

Very helpful

I did plumb a blown EFI street Hemi motor years ago for dyno tuning, it had to have the fuel pressure regulator after the last fuel injector so the injectors would have the same amount of fuel pressure at idle and with the regulator boost referenced it would have the same amount of fuel pressure at WOT

On your deal I wouldn't hesitate to use a sytem with the bypass return fuel line feeding off the pump instead of running another fuel line back to the rear of the car from the fuel regulator up front

I figured(SWAG

) my Duster would empty the fuel bowls in less than .3 of a second at WOT and use all the fuel in the 1/2 inch line in the first two to three seconds of a running it at WOT

Posted By: jamesc

Re: Return line fuel system? - 11/28/13 03:19 AM

there are plenty of dead head systems out there working fine. you never mentioned any specifics though. how much HP, what pump, regulator and line do you plan to use etc.

the simplest, most effective dead head system is to put the regulator between the carb bowl feeds. if you put the regulator at the rear of the car at the very least you should monitor the pressure at the carb under full power so you can adjust the regulator to compensate for line losses. HOWEVER you could potentially end up needing to set the line pressure high to maintain necessary pressure that will be too high for low speed/idle situations and have problems sinking the floats.

personally i would NOT want to put the regulator on a dead head system at the rear of the car, this is against established procedures.

Posted By: MR_P_BODY

Re: Return line fuel system? - 11/28/13 03:25 AM

Quote:

there are plenty of dead head systems out there working fine. you never mentioned any specifics though. how much HP, what pump, regulator and line do you plan to use etc.

the simplest, most effective dead head system is to put the regulator between the carb bowl feeds. if you put the regulator at the rear of the car at the very least you should monitor the pressure at the carb under full power so you can adjust the regulator to compensate for line losses. HOWEVER you could potentially end up needing to set the line pressure high to maintain necessary pressure that will be too high for low speed/idle situations and have problems sinking the floats.

personally i would NOT want to put the regulator on a dead head system at the rear of the car, this is against established procedures.

I would NEVER put a dead head reg at the rear for a
few reasons.. the head pressure you need on a hard
launch and the temp of the fuel... cool/cold fuel
helps drop the intake temp which is more power

Posted By: jamesc

Re: Return line fuel system? - 11/28/13 03:45 AM

to calculate the back pressure during acceleration multiply .315 (for sunoco purple) x the linear length of the fuel line x the G force. this does not mean measure the total length of line but the distance between the carb and the pump. contrary to popular belief with regards to acceleration back pressure line diameter does not have an effect.

if the distance is 10' and the car pulls 1G on launch the back pressure is 3.15 PSI (at launch) however the G force falls off pretty rapidly unless it's a rather fast car

Posted By: MR_P_BODY

Re: Return line fuel system? - 11/28/13 03:52 AM

Yep.. I understand the line pressure... but to me the
biggest factor was always the temp... even with a
electric pump and the reg at the rear its no difference
than having a mech pump that vapor locks(same pressure
up front as a mech pump)

Posted By: jamesc

Re: Return line fuel system? - 11/28/13 04:00 AM

Quote:

Yep.. I understand the line pressure... but to me the
biggest factor was always the temp... even with a
electric pump and the reg at the rear its no difference
than having a mech pump that vapor locks(same pressure
up front as a mech pump)

well actually it isn't the same. with an electric pump/regulator at the rear the line to the front is under pressure not suction as it is with a mechanical pump. pumps cavitate at the suction not the discharge. this happens when the NPSH (net positive suction head) drops below the vapor pressure of the fluid being pumped at the temperature and pressure observed at the pump suction. you can of course have fuel boiling in the mechanical pump discharge

having said that i would NOT put the regulator at the rear of the car that's just bad engineering

Posted By: MR_P_BODY

Re: Return line fuel system? - 11/28/13 04:07 AM

Quote:

Quote:

Yep.. I understand the line pressure... but to me the
biggest factor was always the temp... even with a
electric pump and the reg at the rear its no difference
than having a mech pump that vapor locks(same pressure
up front as a mech pump)

well actually it isn't the same. with an electric pump/regulator at the rear the line to the front is under pressure not suction as it is with a mechanical pump. pumps cavitate at the suction not the discharge. this happens when the NPSH (net positive suction head) drops below the vapor pressure of the fluid being pumped at the temperature and pressure observed at the pump suction. you can of course have fuel boiling in the mechanical pump discharge

having said that i would NOT put the regulator at the rear of the car that's just bad engineering

It wasnt the suction side that had the issue... it
was the low pressure (7 psi) on the outlet side getting hot
that caused vapor lock(boiling the fuel)

Posted By: 70HemiGTX

Re: Return line fuel system? - 11/28/13 04:18 AM

Very interesting.....

Posted By: SLOW67

Re: Return line fuel system? - 11/28/13 04:26 AM

Quote:

Your gonna do what you want... but in my opinion a
return is a much better set up.. but what do I know..
I didnt stay in a Holiday Inn.. but I did work in the
fuel lab for 30+ years... when we started with perf
or injected we ran a return line... some time later
we dropped it... for 1 reason.. repeat.. 1 reason ONLY
and that was cost... but the company will do anything
to cut cost... but I also understand a budget... but
also sometimes you need to save a bit more before
you jump........... JMO

I'm going to rerun the return

Posted By: MR_P_BODY

Re: Return line fuel system? - 11/28/13 04:56 AM

Thumper, when he's running 10s with $1000 in china-bay and junkyard parts while cruising down the street at 2500 rpm or less, you may rethink all the "good stuff" in your big block

I'll take my chances with better quality parts...
I tend to buy American made stuff if at all possible
but thats me... I dont care if I have to save a bit
longer to get them.. or maybe I have to do a extra
side job to cover it

Posted By: cudaman1969

Re: Return line fuel system? - 11/28/13 05:56 AM

I used the Morroso bleed off regulator. The reg. was set at 8# and excess fuel bled back to tank with no restriction to the carbs since they fed directly from pump. At idle alot of bleed off, full throttle none. Worked great I'll use it again on my next car.

Posted By: SLOW67

Re: Return line fuel system? - 11/28/13 06:03 AM

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Quote:

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In a returnless system I understand that fuel is warmer when it gets to the carb as opposed to a return system. My question is how much of a difference does it really make? I am preparing to make my fuel system NHRA approved and I can save alot of money putting my reg. in the trunk with the pump and tank and just running my low pressure side to the front of the car. Will there really be that much of a difference on a street/strip car?

This is at least the 2nd time in two post that you used the terms "cheap" and sometimes it works but generally it doesn`t........just check out past posts about dampners, heads pumps etc. Don`t cheap out on the fuel system or it will bite you in the azz............

I understand what your saying, but I don't have much if any of a budget sometimes and I've literally built this car myself with the cheapest speed parts I can find and none have let me down yet. In over 2 years I've put close to 20k miles on this setup that was built entirely from chinese ebay parts and the only part to let me down has been the head gaskets, one of which was the original from 1976.

I like the idea of running one less line to the front for two reasons, one CHEAP and two, anywhere I can simplify or make a system more modular I will do it. If I only have one line to the front of the car it will make it so my pump, reg., and tank are all in one place. Easier to start looking for problems if one arose, and makes for a simple install.

I get it............I`m not money bags like some either cos if I was I`d be driving an 8-second car and have the best of everything however, I but good stuff when I can and wait if I can`t. Some people actually brag about e-bag stuff, chinese this and that and if that`s your gig go for it.

Thumper, when he's running 10s with $1000 in china-bay and junkyard parts while cruising down the street at 2500 rpm or less, you may rethink all the "good stuff" in your big block

When I get the 360 in and can afford a good converter it should be running high 10's

My last track pass was a 7.82 at 96 in the 1/8th. My 60' is terrible but my N20 kit should fix that when I get it wired finally. Keep in mind this is with a BONE STOCK 76 318. It gets right at 16mpg on the way to cruise-ins and will run on 87 octane if I turn the boost down and the timing back

Ebay parts are the only way I could afford to make any power. I've got less in my whole turbo setup, fuel system and electronics than it would have cost me to build a 450hp 360. The only thing I spent good money on was the rearend it has Dr. Diff axles

Posted By: dartman366

Re: Return line fuel system? - 11/28/13 06:44 AM

I have been running a by-pass system for quite a number years now and it has worked flawless.....till I switched to E-85 this summer and installed a new Mallory comp 250 pump as opposed to the comp 140 that I had run before, now I cannot get the fuel pressure low enough so I am installing a new -10an return line and fittings as the -08an isn't big enough and creates a restriction,,I also run a fuel log right on the carb and run the supply line right to it so the carb gets full volume, then a line to the regulator then use the regulater to bleed off unneeded fuel back to the cell. works great and the pump doesnt strain and runs much quieter and cooler.

Posted By: OUTLAWD

Re: Return line fuel system? - 11/28/13 03:04 PM

I ran my feed/return with 1/2 ss hardline. Ended up being less than $2/ft IIRC. Some swagelok type fittings from McMaster, a borrowed tubing bender, and a satuday was all I needed. All those an fittings add up quickly though!

Posted By: Thumperdart

Re: Return line fuel system? - 11/28/13 05:36 PM

Quote:

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In a returnless system I understand that fuel is warmer when it gets to the carb as opposed to a return system. My question is how much of a difference does it really make? I am preparing to make my fuel system NHRA approved and I can save alot of money putting my reg. in the trunk with the pump and tank and just running my low pressure side to the front of the car. Will there really be that much of a difference on a street/strip car?

This is at least the 2nd time in two post that you used the terms "cheap" and sometimes it works but generally it doesn`t........just check out past posts about dampners, heads pumps etc. Don`t cheap out on the fuel system or it will bite you in the azz............

I understand what your saying, but I don't have much if any of a budget sometimes and I've literally built this car myself with the cheapest speed parts I can find and none have let me down yet. In over 2 years I've put close to 20k miles on this setup that was built entirely from chinese ebay parts and the only part to let me down has been the head gaskets, one of which was the original from 1976.

I like the idea of running one less line to the front for two reasons, one CHEAP and two, anywhere I can simplify or make a system more modular I will do it. If I only have one line to the front of the car it will make it so my pump, reg., and tank are all in one place. Easier to start looking for problems if one arose, and makes for a simple install.

I get it............I`m not money bags like some either cos if I was I`d be driving an 8-second car and have the best of everything however, I but good stuff when I can and wait if I can`t. Some people actually brag about e-bag stuff, chinese this and that and if that`s your gig go for it.

Thumper, when he's running 10s with $1000 in china-bay and junkyard parts while cruising down the street at 2500 rpm or less, you may rethink all the "good stuff" in your big block

Doubt it..............plus 9`s are WAY more fun than 10`s but thankxxx 4 ur concern..........

Posted By: Chris2581

Re: Return line fuel system? - 11/28/13 05:45 PM

Quote:

I used the Morroso bleed off regulator. The reg. was set at 8# and excess fuel bled back to tank with no restriction to the carbs since they fed directly from pump. At idle alot of bleed off, full throttle none. Worked great I'll use it again on my next car.

Have a part number for this? Or is it the Moroso fuel pressure log?

Posted By: Cab_Burge

Re: Return line fuel system? - 11/28/13 06:51 PM

I forgot to mention that all the Magnafuel fuel pumps have a builtin bypass from the front of the pump, high pressure side, that you run back into the tank so it is a bypass system with no return line from the front

I mount my regulators in front of the motor so the high pressures is all the way to the front of the motor and the lower regulated pressure is to the carb.

I haven't ran a dead headed system since switching from the smaller dead head pumps like the little blue 110GPH Holleys and the Mallory 140 GPH pumps

One thing you really need to make sure of on a drag car is that you really have more fuel delivery than you need

If you can not jet your car up enough to slow it down in the 1/4 mile MPH you don't have enough fuel volume

Posted By: Thumperdart

Re: Return line fuel system? - 11/28/13 07:24 PM

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I forgot to mention that all the Magnafuel fuel pumps have a builtin bypass from the front of the pump, high pressure side, that you run back into the tank so it is a bypass system with no return line from the front I mount my regulators in front of the motor so the high pressures is all the way to the front of the motor and the lower regulated pressure is to the carb. I haven't ran a dead headed system since switching from the smaller dead head pumps like the little blue 110GPH Holleys and the Mallory 140 GPH pumps One thing you really need to make sure of on a drag car is that you really have more fuel delivery than you need If you can not jet your car up enough to slow it down in the 1/4 mile MPH you don't have enough fuel volume

Agreed...........I love the Magnafuel 300 pump and it too bypasses directly into the cell which saves lots of extra fuel line and fittings and looks cleaner to boot.............

Posted By: Quicktree

Re: Return line fuel system? - 11/28/13 08:26 PM

what are you guys running for the return line going into the fuel cell?

Posted By: Thumperdart

Re: Return line fuel system? - 11/28/13 08:50 PM

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what are you guys running for the return line going into the fuel cell?

Number 8.............

Posted By: Quicktree

Re: Return line fuel system? - 11/28/13 08:57 PM

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Quote:

what are you guys running for the return line going into the fuel cell?

Number 8.............

I meant is there some kind of tube going in the cell or just dumping it back in from the top. my arrow just dumps it back in.

Posted By: cudaman1969

Re: Return line fuel system? - 11/28/13 08:59 PM

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Quote:

I used the Morroso bleed off regulator. The reg. was set at 8# and excess fuel bled back to tank with no restriction to the carbs since they fed directly from pump. At idle alot of bleed off, full throttle none. Worked great I'll use it again on my next car.

Have a part number for this? Or is it the Moroso fuel pressure log?

I think it's the fuel log, been about 8 years, worked well, 5.60- 125 in the eighth mile

Posted By: dartman366

Re: Return line fuel system? - 11/28/13 09:00 PM

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what are you guys running for the return line going into the fuel cell?

currently -08, will be upgrading to -10 this winter.

Posted By: dartman366

Re: Return line fuel system? - 11/28/13 09:02 PM

Quote:

Quote:

Quote:

what are you guys running for the return line going into the fuel cell?

Number 8.............

I meant is there some kind of tube going in the cell or just dumping it back in from the top. my arrow just dumps it back in.

mine just dumps in like yours.

Posted By: BobR

Re: Return line fuel system? - 11/28/13 10:13 PM

Quote:

Thumper, when he's running 10s with $1000 in china-bay and junkyard parts while cruising down the street at 2500 rpm or less, you may rethink all the "good stuff" in your big block

Moparts is the epitome of "budget" parts. Not everyone but quite a few. I buy nothing but the best. My life is worth that to me.

Posted By: Thumperdart

Re: Return line fuel system? - 11/28/13 10:30 PM

Quote:

Quote:

Quote:

what are you guys running for the return line going into the fuel cell?

Number 8.............

I meant is there some kind of tube going in the cell or just dumping it back in from the top. my arrow just dumps it back in.

No tube in mine but doesn`t seem to be a problem plus I installed a few foam blocks to help aeration..........

Posted By: 440dart

Re: Return line fuel system? - 11/29/13 02:47 AM

I run a BG 250 pump, on a street car. this is the way I was told to run the return line. Before the return system was installed, the pump allways sounded like it was laboring, and very loud. Now with the return, you almost can't here it with the engine running. It holds a constant 7 lbs.

Attached picture 7939918-102_2455.JPG

Posted By: 440dart

Re: Return line fuel system? - 11/29/13 02:49 AM

2nd. pic.

Posted By: Cab_Burge

Re: Return line fuel system? - 11/29/13 02:58 AM

Quote:

what are you guys running for the return line going into the fuel cell?

On my Duster I had a 1/2 inch stainless tube fabricated to fit into the stock tank sending unit, it had a #8 steel JIC male fitting welded into the sender cap so I could use a #8 AN hose end to hook the return line from the pump onto it. It dumped into the bottom of the tank pointed away from the sump

My new car dumps the return E85 fuel into the top of the tank, I should probally reroute it into the bottom drain, but I'm afraid of hitting that hose and fitting somehow, ending up with a possible fire or some other nasty consequence

Posted By: Quicktree

Re: Return line fuel system? - 11/29/13 03:05 AM

Quote:

2nd. pic.

is that a dead head regulator used as a return?

Posted By: tubtar

Re: Return line fuel system? - 11/29/13 05:39 AM

-8 feed and -10 return. That's what was recommended by BG for my stuff , and I wasn't gonna argue. HR240 pump and I forget the filter #........9000 maybe ? I called to ask why the bigger return line and was told that it provides for more consistent pressure because of no resistance in the return line. The regulator is after the carb by about 15" of line. I guess it works on paper.

Posted By: tubtar

Re: Return line fuel system? - 11/29/13 05:41 AM

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Quote:

2nd. pic.

is that a dead head regulator used as a return?

No , it's a bypass. I have the same one.

Posted By: Challenger 1

Re: Return line fuel system? - 11/29/13 02:26 PM

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2nd. pic.

I see low flow steel hydraulic fittings, should use tube 90,60, 45s on fuel systems. Also notice the settings are weird.

Also I would not run the gauge during normal running. Just used it to set it up and then take out and plug it. It won't live like that.

Posted By: Challenger 1

Re: Return line fuel system? - 11/29/13 02:29 PM

Quote:

I run a BG 250 pump, on a street car. this is the way I was told to run the return line. Before the return system was installed, the pump allways sounded like it was laboring, and very loud. Now with the return, you almost can't here it with the engine running. It holds a constant 7 lbs.

A regulator, bypass etc should never be mounted solid to the motor, because vibration will unset the regulator and cause cracks in your fittings hanging on the end like that...if you make power.

Posted By: BobR

Re: Return line fuel system? - 11/29/13 05:25 PM

Quote:

Quote:

2nd. pic.

is that a dead head regulator used as a return?

It's a return style regulator. 440Dart is my brother.

Posted By: BobR

Re: Return line fuel system? - 11/29/13 05:27 PM

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Quote:

I run a BG 250 pump, on a street car. this is the way I was told to run the return line. Before the return system was installed, the pump allways sounded like it was laboring, and very loud. Now with the return, you almost can't here it with the engine running. It holds a constant 7 lbs.

A regulator, bypass etc should never be mounted solid to the motor, because vibration will unset the regulator and cause cracks in your fittings hanging on the end like that...if you make power.

That motor makes about 700 HP. You may be right about the solid mounting but it's been that way for 4+ years. He's had zero issues and he drives it on the street pretty regularly.

Posted By: mafo

Re: Return line fuel system? - 11/29/13 06:35 PM

I use a slightly different setup, cant say if it s better or not but it seems to work

Attached picture 7940417-ss_bypass_4.jpg

Posted By: SLOW67

Re: Return line fuel system? - 11/30/13 02:28 AM

Mine currently has a Mallory 4309 reg. that is boost referenced and a 3/8 feed and return to the tank, with a walbro 190 pump. It just dumps back in the top of the cell but I do have foam in it. Right now it is all plumbed in 3/8 fuel injection hose so NHRA frowns on that plus its a safety item too I suppose. I wanted to simplify it and upgrade the line at the same time but I guess I'll just buy twice the material and put it back the way it is.

Posted By: MR_P_BODY

Re: Return line fuel system? - 11/30/13 02:50 AM

Quote:

Mine currently has a Mallory 4309 reg. that is boost referenced and a 3/8 feed and return to the tank, with a walbro 190 pump. It just dumps back in the top of the cell but I do have foam in it. Right now it is all plumbed in 3/8 fuel injection hose so NHRA frowns on that plus its a safety item too I suppose. I wanted to simplify it and upgrade the line at the same time but I guess I'll just buy twice the material and put it back the way it is.

Are you saying its all rubber hose... change that out
and run tubing

Posted By: dartman366

Re: Return line fuel system? - 11/30/13 02:58 AM

Quote:

Quote:

Mine currently has a Mallory 4309 reg. that is boost referenced and a 3/8 feed and return to the tank, with a walbro 190 pump. It just dumps back in the top of the cell but I do have foam in it. Right now it is all plumbed in 3/8 fuel injection hose so NHRA frowns on that plus its a safety item too I suppose. I wanted to simplify it and upgrade the line at the same time but I guess I'll just buy twice the material and put it back the way it is.

Are you saying its all rubber hose... change that out
and run tubing

Definately.