Fuel system return line location
#3061264
07/21/22 10:42 AM
07/21/22 10:42 AM
|
Joined: Dec 2021
Posts: 1,145 Loudoun County, VA
Brad_Haak
OP
super stock
|
OP
super stock
Joined: Dec 2021
Posts: 1,145
Loudoun County, VA
|
If you're adding a return line for an electric fuel pump where the pump is at the rear of the car near the fuel tank, would it be better to add the return at the regulator at the front of the car that feeds the carbs, or put it directly after the fuel pump before the main feed line to the carb regulator?
Traditional(?) approach...
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
|
|
|
Re: Fuel system return line location
[Re: Brad_Haak]
#3061266
07/21/22 10:43 AM
07/21/22 10:43 AM
|
Joined: Dec 2021
Posts: 1,145 Loudoun County, VA
Brad_Haak
OP
super stock
|
OP
super stock
Joined: Dec 2021
Posts: 1,145
Loudoun County, VA
|
"Short line" approach right after pump...
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
|
|
|
Re: Fuel system return line location
[Re: Brad_Haak]
#3061269
07/21/22 10:47 AM
07/21/22 10:47 AM
|
Joined: Aug 2011
Posts: 2,864 Pattison Texas
CSK
master
|
master
Joined: Aug 2011
Posts: 2,864
Pattison Texas
|
For a street car in the heat, I like the return regulator as close to the carb as possible , a fuel log at the carb with the regulator on the end .
Last edited by csk; 07/21/22 11:02 AM.
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
|
|
|
Re: Fuel system return line location
[Re: Brad_Haak]
#3061272
07/21/22 10:54 AM
07/21/22 10:54 AM
|
Joined: Mar 2003
Posts: 2,514 PA
moparacer
master
|
master
Joined: Mar 2003
Posts: 2,514
PA
|
My car had the short line setup on it with a Mallory Comp 250 pump for years with no problems. A lot less plumbing with that setup. Comes right off the pump and into the tank....All in the trunk.
I don't know about now, but we had issues years ago with the return style regulators. You have to run a larger line for the return and need to be as little restriction as possible on the return line or you get into pressure issues.
67 Barracuda street/bracket car 11.27-119 68 Dart 502 BB 8.70s-152 414 cid SB Dragster 7.65-174
|
|
|
Re: Fuel system return line location
[Re: Brad_Haak]
#3061273
07/21/22 10:55 AM
07/21/22 10:55 AM
|
Joined: Jan 2003
Posts: 17,875 S.E. Michigan
ZIPPY
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 17,875
S.E. Michigan
|
I like the regulator in the engine bay for the same reason as Charlie, street car in the heat.
At low speeds on the street will be bypassing a large amount of fuel. This is good for a real street car that is driven in hot weather, because there is a cooling effect added by the constant movement of the fuel. But the extra plumbing is a definite downside.
Rich H.
Esse Quam Videri
|
|
|
Re: Fuel system return line location
[Re: Brad_Haak]
#3061293
07/21/22 11:47 AM
07/21/22 11:47 AM
|
Joined: Dec 2021
Posts: 1,145 Loudoun County, VA
Brad_Haak
OP
super stock
|
OP
super stock
Joined: Dec 2021
Posts: 1,145
Loudoun County, VA
|
Yep, ease of conversion vs overall effectiveness... I appreciate all the feedback.
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
|
|
|
Re: Fuel system return line location
[Re: Brad_Haak]
#3061327
07/21/22 01:04 PM
07/21/22 01:04 PM
|
Joined: Dec 2005
Posts: 11,611 Fulton County, PA
CMcAllister
Mr. Helpful
|
Mr. Helpful
Joined: Dec 2005
Posts: 11,611
Fulton County, PA
|
Up front. Keep it moving. Rather than lying there deadheaded against a regulator.
If the results don't match the theory, change the theory.
|
|
|
Re: Fuel system return line location
[Re: Brad_Haak]
#3061342
07/21/22 01:33 PM
07/21/22 01:33 PM
|
Joined: Jan 2003
Posts: 5,444 Indiana
YO7_A66
master
|
master
Joined: Jan 2003
Posts: 5,444
Indiana
|
I used a lower budget way of regulating the fuel back to the tank. My thought was to keep the fuel moving at the carb, so my setup is shown below and my regulator is a .028" Holley jet in the return line up by the carb. It took a few jet sizes to get the final psi at the carb right, but the .028" worked out about 6.2psi at the carb and the rest of the fuel goes to the tank.
1970 YO7 A66 [Canadian Export] F8 Challenger 340 (Currently in shop for stroker assy.)
|
|
|
Re: Fuel system return line location
[Re: CMcAllister]
#3061345
07/21/22 01:37 PM
07/21/22 01:37 PM
|
Joined: Jan 2003
Posts: 8,028 Tulsa OK
Bad340fish
master
|
master
Joined: Jan 2003
Posts: 8,028
Tulsa OK
|
My car is EFI but it is plumbed with the regulator up front. Being a street car the recirculating fuel heats up pretty fast, it eventually gets all the fuel hot. My return fuel temp runs 120 degrees pretty easily and that is with running it through a cooler with a fan on it . Like Andy said a lot of EFI setups are starting to keep the regulator in the back to keep from returning hot fuel. I will eventually try that but have other items on the list first.
Couple of things to add, my car returns from the rails so that adds heat, I also didn't log temps before I added the fuel cooler so I really don't know how much it helps, it is back behind the stock fuel tank.
68 Barracuda Formula S 340
|
|
|
Re: Fuel system return line location
[Re: ZIPPY]
#3061352
07/21/22 01:49 PM
07/21/22 01:49 PM
|
Joined: Jan 2003
Posts: 13,374 Marion, South Carolina [><]
an8sec70cuda
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 13,374
Marion, South Carolina [><]
|
I like the regulator in the engine bay for the same reason as Charlie, street car in the heat.
At low speeds on the street will be bypassing a large amount of fuel. This is good for a real street car that is driven in hot weather, because there is a cooling effect added by the constant movement of the fuel. But the extra plumbing is a definite downside.
This. Here's my setup. Return regulator is the red Aeromotive regulator at the end of the log. -10 feed, -8 return. The return is plumbed into the stock 3/8" pickup tube. Pickup is from a sump in the tank.
CHIP '70 hemicuda, 575" Hemi, 727, Dana 60 '69 road runner, 440-6, 18 spline 4 speed, Dana 60 '71 Demon, 340, low gear 904, 8.75 '73 Chrysler New Yorker, 440, 727, 8.75 '90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt '06 GMC 2500HD LBZ Duramax
|
|
|
Re: Fuel system return line location
[Re: an8sec70cuda]
#3061452
07/21/22 05:09 PM
07/21/22 05:09 PM
|
Joined: Dec 2021
Posts: 1,145 Loudoun County, VA
Brad_Haak
OP
super stock
|
OP
super stock
Joined: Dec 2021
Posts: 1,145
Loudoun County, VA
|
I need to do some form of return system just to reduce the load on the Mallory 140 w/ the dead-head regulator. I remember that thing starting to sing the blues on occasion while stuck in summer traffic and would like to avoid repeating that scenario as much as possible.
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
|
|
|
Re: Fuel system return line location
[Re: Brad_Haak]
#3061490
07/21/22 07:41 PM
07/21/22 07:41 PM
|
Joined: Sep 2014
Posts: 4,457 Washington
madscientist
master
|
master
Joined: Sep 2014
Posts: 4,457
Washington
|
I need to do some form of return system just to reduce the load on the Mallory 140 w/ the dead-head regulator. I remember that thing starting to sing the blues on occasion while stuck in summer traffic and would like to avoid repeating that scenario as much as possible. The bypass should always be at the carb. Never back at the pump. If you put it at the pump, it takes much longer for the system to respond to the floats dropping. A short return line looks good on paper, but in practice it’s bad. And, think of all the fuel in the line from the pump to the carb. It’s still just sitting there, heat soaking. One last piece of advice. Buy a Mallory regulator. The one you have in the first post is just a sorry excuse for a bypass regulator. Running the fuel backward through a modified dead head regulator is not good. Use a dedicated bypass regulator.
Last edited by madscientist; 07/21/22 07:43 PM.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
|
|
|
Re: Fuel system return line location
[Re: Brad_Haak]
#3061626
07/22/22 01:31 PM
07/22/22 01:31 PM
|
Joined: Mar 2007
Posts: 3,285 West Coast, USA
jbc426
master
|
master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
|
Some fuel pumps bypass at a higher than optimal carburetor pressure directly at the pump to keep the pump cooler. The bypass regulator up front also bypasses fuel, but at a much lower volume than the fuel pump is bypassing. I ran my fuel system like that for years at the recommendation of a fuel systems engineer.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's 1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
|
|
|
Re: Fuel system return line location
[Re: jbc426]
#3061794
07/23/22 09:24 AM
07/23/22 09:24 AM
|
Joined: Dec 2021
Posts: 1,145 Loudoun County, VA
Brad_Haak
OP
super stock
|
OP
super stock
Joined: Dec 2021
Posts: 1,145
Loudoun County, VA
|
I'm looking at RobbMc's regulator to go along with his 1/2" sending unit that includes a return feed. https://www.robbmcperformance.com/products/regulator_bp.html
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
|
|
|
Re: Fuel system return line location
[Re: AndyF]
#3061868
07/23/22 02:46 PM
07/23/22 02:46 PM
|
Joined: Dec 2021
Posts: 1,145 Loudoun County, VA
Brad_Haak
OP
super stock
|
OP
super stock
Joined: Dec 2021
Posts: 1,145
Loudoun County, VA
|
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
|
|
|
Re: Fuel system return line location
[Re: Brad_Haak]
#3062178
07/24/22 06:23 PM
07/24/22 06:23 PM
|
Joined: Jan 2003
Posts: 19,375 Las Vegas
Al_Alguire
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 19,375
Las Vegas
|
FWIW I tried a return system on my street car, ie pump gas car thats not used alot. After having to replace the return line for what would have been the third time, in 8 years I decided to NOT use the return regulator and line(mounted near carb) and just use the pump bypass. No ill affects, no issues in traffic in Vegas heat and no difference at the track, been like this for 14 years. Pump has been in the car for 22 years....Never had to touch it.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
|
|
|
Re: Fuel system return line location
[Re: Al_Alguire]
#3062197
07/24/22 07:47 PM
07/24/22 07:47 PM
|
Joined: Sep 2014
Posts: 4,457 Washington
madscientist
master
|
master
Joined: Sep 2014
Posts: 4,457
Washington
|
FWIW I tried a return system on my street car, ie pump gas car thats not used alot. After having to replace the return line for what would have been the third time, in 8 years I decided to NOT use the return regulator and line(mounted near carb) and just use the pump bypass. No ill affects, no issues in traffic in Vegas heat and no difference at the track, been like this for 14 years. Pump has been in the car for 22 years....Never had to touch it. What was going wrong with the return line?
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
|
|
|
Re: Fuel system return line location
[Re: Al_Alguire]
#3062200
07/24/22 07:58 PM
07/24/22 07:58 PM
|
Joined: Mar 2003
Posts: 2,514 PA
moparacer
master
|
master
Joined: Mar 2003
Posts: 2,514
PA
|
FWIW I tried a return system on my street car, ie pump gas car thats not used alot. After having to replace the return line for what would have been the third time, in 8 years I decided to NOT use the return regulator and line(mounted near carb) and just use the pump bypass. No ill affects, no issues in traffic in Vegas heat and no difference at the track, been like this for 14 years. Pump has been in the car for 22 years....Never had to touch it. Same here, pumps been on the car since the 90s. If I went back to a carb I would run the single line to the carb and let it eat.
67 Barracuda street/bracket car 11.27-119 68 Dart 502 BB 8.70s-152 414 cid SB Dragster 7.65-174
|
|
|
|
|