Fuel Line Size

[Runner 68]

Sorry if this question has been kicked around before but I couldn't find satisfaction in searching FBBO.
I'm sure I will get a 50/50 split on here as I have talking to friends and gurus I know.
68 Runner, carbureted 850CFM, 500" stroker, ~600-650HP, internal tank EFI fuel pump regulated for carb, AN-6 or AN-8 Fuel line?
As my engine designer says "Stop Light **** Talking Poser". This car will not see the track but has a moderate race mill on pump gas.
Looking forward to input from the Mopar Gods on here.

 

[sabre67]

my suggestion would be a bypass .regulator with a return to tank and 6an is fine

 

[pnora]

If your starting from new go big. With the pump in the tank you will push more fuel than you can pull. Some EFI pumps have internal regulation. You could always do a volume test on a section of line and that will give you your GPH or what ever measurement unit you want to use.

 

[dadsbee]

650hp is under 60gph fuel burn at full throttle. Good pump and a 3/8ths line will feed that all day long

 

[diesel_lv]

+1 for -6AN, 3/8". I run it on my 610hp fuel injected 496, and carbed 700hp 4.6 turbo jet boat. No problems on either.

 

[kiwigtx]

my suggestion would be a bypass .regulator with a return to tank and 6an is fine

-6AN is fine, but with EFI you cannot use a Bypass regulator.

Full flow and a separate return line is a must.

Dead-heading will not work.

 

[Runner 68]

Thanks everyone. 6-AN / 3/8 is the direction I was leaning for this set up for a variety of reasons.
Yes, bypass regulator. Yes, return line. No EFI, 850 carb. Just an EFI pump.
Thanks for helping confirm my decision. 6-AN makes several things much simpler in this application.

Gotta love this place.

 

[sabre67]

I stand corrected,should have said no deadheading regulator,return to tank

 

[kiwigtx]

I stand corrected,should have said no deadheading regulator,return to tank

I know this to be true because I foolishly tried it before changing to flow and separate return lines.

 

[sabre67]

Confirmed

 

[Runner 68]

I know this to be true because I foolishly tried it before changing to flow and separate return lines.

Dead heading tends to fry pumps.

 

[dusterkid]

I'd go for the -6an as well, esp since it's not a race car.

 

[4mulas]

6an will support that. If you have future upgraded **** talking plans consider 8an…

 

[33 IMP]

I've had 1/2 aluminum line with -8 hoses and fittings in my cars for years. It's probably overkill however. Pump and lines are capable of supporting twice the power I've got at the moment. I'm set up for a 200-400 hp increase.
3/8, -6 should be fine for your app.

 

[RJRENTON]

-6AN is fine, but with EFI you cannot use a Bypass regulator.

Full flow and a separate return line is a must.

Dead-heading will not work.

I would think it would depend on the EFI system......Throttle Body Injection (TBI), Multi-Point (1/N, where N = number of cylinders / fuel charge per cyljnder, simultaneously), Sequential (leads but replicates firing order), or GDI (Gasoline Direct Injection which leads firing order by mili seconds). Each system has specific fuel pressure and volume requirements.....the highest of which is GDI where fuel pressure at the injector is ~ 1800 PSI and the least volume and pressure requirement of the TBI, which is ~ 20-22 PSI. There is no "universal line size" but can be calculated at maximum fuel VOLUME and PRESSURE, factoring in line losses (pressure drops). Most factory systems use a reducing regulator in the system to maintain a steady state pressure condition. Perhaps it would be best to determine the EFI system being used b4 erroneous assumptions are made......just a thought.....
BOB RENTON