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Re: Return line fuel system?
[Re: SLOW67]
#1540679
11/27/13 07:08 PM
11/27/13 07:08 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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A lot of variables here but you can see 30+ degrees difference... will 30* be a problem.. again it will depend... but cooler fuel is ALWAYS a plus 
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Re: Return line fuel system?
[Re: SLOW67]
#1540681
11/27/13 07:16 PM
11/27/13 07:16 PM
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Joined: Aug 2011
Posts: 2,872
Pattison Texas
CSK
master
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master
Joined: Aug 2011
Posts: 2,872
Pattison Texas
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it works much better with the return regulator closer to the carb,volume & consistent pressure.
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
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Re: Return line fuel system?
[Re: SLOW67]
#1540682
11/27/13 07:23 PM
11/27/13 07:23 PM
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Joined: Mar 2006
Posts: 9,910
Eighty Four, PA
B G Racing
master
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master
Joined: Mar 2006
Posts: 9,910
Eighty Four, PA
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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?
It is recommended that for most application with a single line system to place the regulator as close to the carb as possible for race applications.For low HP street applications you can get regulated pumps that are pre set.For a single line race application it is suggested to run a bypass line from the pump to the tank and set bypass pressure to 18 to 28 lbs.
For your street strip application,just buy a preset pump since some of the race style pump will run hot and wear out even if you put the regulator at the pump it willcreate back pressure against the normal push of the pump.This is the main reason race pumps are not recommended for the street they are designed for short duration running and can bypass or circulate fuel with out too much back pressure. 
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Re: Return line fuel system?
[Re: B G Racing]
#1540683
11/27/13 08:46 PM
11/27/13 08:46 PM
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Joined: Jun 2003
Posts: 9,225
Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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I have my regulator after the carb but still very close so the only fuel to get warm is what is in the carb
Gen 3 power 6.22@110, 9.85@135
Follow @g3hemiswap on instagram
performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs
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Re: Return line fuel system?
[Re: Thumperdart]
#1540688
11/27/13 10:43 PM
11/27/13 10:43 PM
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Joined: Sep 2009
Posts: 928
NC
SLOW67
OP
super stock
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OP
super stock
Joined: Sep 2009
Posts: 928
NC
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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.
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Re: Return line fuel system?
[Re: SLOW67]
#1540689
11/27/13 11:15 PM
11/27/13 11:15 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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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
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Re: Return line fuel system?
[Re: SLOW67]
#1540690
11/27/13 11:17 PM
11/27/13 11:17 PM
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Joined: Aug 2003
Posts: 43,307
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,307
Bend,OR USA
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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
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Return line fuel system?
[Re: jamesc]
#1540692
11/27/13 11:25 PM
11/27/13 11:25 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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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
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Re: Return line fuel system?
[Re: jamesc]
#1540694
11/27/13 11:52 PM
11/27/13 11:52 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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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)
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Re: Return line fuel system?
[Re: MR_P_BODY]
#1540695
11/28/13 12:00 AM
11/28/13 12:00 AM
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Joined: Jan 2003
Posts: 5,875
communist bloc of new jersey
jamesc
master
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master
Joined: Jan 2003
Posts: 5,875
communist bloc of new jersey
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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
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Re: Return line fuel system?
[Re: jamesc]
#1540696
11/28/13 12:07 AM
11/28/13 12:07 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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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)
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