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efi question

Started by Semaphore, December 24, 2014, 07:15:28 PM

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Semaphore

Will a 1/4 return line be large enough as fuel return  line

Thank you

cdr

most need at least 5/16,but i would run a 3/8
LINK TO MY STORY http://www.onallcylinders.com/2015/11/16/ride-shares-charlie-keel-battles-cancer-ms-to-build-brilliant-1968-dodge-charger/  
                                                                                           
68 Charger 512 cid,9.7to1,Hilborn EFI,Home ported 440 source heads,small hyd roller cam,COLD A/C ,,a518 trans,Dana 60 ,4.10 gear,10.93 et,4100lbs on street tires full exhaust daily driver
Charger55 by Charlie Keel, on Flickr

Rolling_Thunder

Depends on the volume of the pump you're running -  3/8 feed and 5/16 return....     I ran a -8AN and a -6AN return on my old system
1968 Dodge Charger - 6.1L Hemi / 6-speed / 3.55 Sure Grip

2013 Dodge Challenger R/T - 5.7L Hemi / 6-speed / 3.73 Limited Slip

1964 Dodge Polara 500 - 440 / 4-speed / 3.91 Sure Grip

1973 Dodge Challenger Rallye - 340 / A-518 / 3.23 Sure Grip

fy469rtse

I think it will be ok , remember its excess fuel from reg just being returned to tank,
As long as your feed line good size ,
That's the one that counts  :2thumbs:

BSB67

Quote from: fy469rtse on December 25, 2014, 06:55:05 AM
I think it will be ok , remember its excess fuel from reg just being returned to tank,
As long as your feed line good size ,
That's the one that counts  :2thumbs:
Right, and depending on the engine demand, the smaller return could cause overpressure (i.e. causing pressure higher than the regulated pressure)

500" NA, Eddy head, pump gas, exhaust manifold with 2 1/2 exhaust with tailpipes
4150 lbs with driver, 3.23 gear, stock converter
11.68 @ 120.2 mph

cdr

so to answer your ?,,no to the 1/4 return . lol
LINK TO MY STORY http://www.onallcylinders.com/2015/11/16/ride-shares-charlie-keel-battles-cancer-ms-to-build-brilliant-1968-dodge-charger/  
                                                                                           
68 Charger 512 cid,9.7to1,Hilborn EFI,Home ported 440 source heads,small hyd roller cam,COLD A/C ,,a518 trans,Dana 60 ,4.10 gear,10.93 et,4100lbs on street tires full exhaust daily driver
Charger55 by Charlie Keel, on Flickr

John_Kunkel


Go by the manufacturer's recommendations. The MSD Atomic specifies 3/8".
Pardon me but my karma just ran over your dogma.

Semaphore

The reason i asked is that there is a 1/4 return on the sender
I gather its for emissions

beezee

 Have the fuel tank sumped ,Instal efi rated hose to the external pump to the fuel regulator and use the original 5/16 or 3/8 fuel line to return to the fuel tank-sender.My stroker has yet to starve for fuel down to a near empty tank.
http://www.forbbodiesonly.com/moparforum/showthread.php?84185-Fuel-return-EFI&highlight=efi

Semaphore

I have purchase a Edelbrock sump that fits under the hood.

http://www.summitracing.com/int/parts/edl-3605

Rolling_Thunder

I've never used that Edelbrock piece but I believe you would send your return line back to that - it is basically a surge tank with an in tank pump for make the high pressure the EFI needs - but doesnt require a high pressure pump in the tank....   you will need a small pump to get the fuel from the tank to the new surge tank though ---  run pressure line from the surge to the fuel rails, then the regulator, which returns fuel to the surge
1968 Dodge Charger - 6.1L Hemi / 6-speed / 3.55 Sure Grip

2013 Dodge Challenger R/T - 5.7L Hemi / 6-speed / 3.73 Limited Slip

1964 Dodge Polara 500 - 440 / 4-speed / 3.91 Sure Grip

1973 Dodge Challenger Rallye - 340 / A-518 / 3.23 Sure Grip

Mike DC

 
IMO the underhood mini-tank & electric pump deal is probably safer for old cars than the standard modern way of EFI conversions.  High-pressure electric fuel pumps are scary if they don't shut off at the right time.  But with an old mechanical pump still bringing fuel from the gas tank to the engine bay area, then the little electric pump runs dry in a few seconds once engine stops turning.   

Semaphore

Hello

I'm going to modify my Edelbock EFI sump and add a connection for a return line.

picture attached show someone has done it already

I would like your thoughts on this mod

Thank you
pete
:shruggy:

rt green

exposed to a lot of heat?
third string oil changer

MechTech

I have been running a 1/4" return line from my motor all the way back to my fuel cell for some time and it has never been a problem. I have a dash gage and run 55psi. The return line is technically a pressure line and will flow more than a suction line. My setup is supporting around 600hp. Having said that when it comes to fuel bigger can't hurt.