What size fuel line

mustangdave · Sep 14, 2005

I plan on switching to the factory 3/8" line to replace my 5/16" line but was wondering:
How much h.p. will each line support on a carb'd. car, mechanical pump, at 6 or 7 p.s.i.?
Anyone have a chart?

ForceFed70 · Sep 14, 2005

Don't have a chart or anything, but I've been told the 3/8ths line is good to around 400-450hp depending on your pump.

mdjay · Sep 14, 2005

That sounds about right for crank horsepower!

My attitude is there is no reason to starve!

dodgestang · Sep 14, 2005

I run 3/8 line....make 400 at the back tire with mechanical pump.

67GTA-FB429 · Sep 14, 2005

So if you were to switch...where would you run the new line?

I ask, because I am thinking of replacing my line with braided steel hose, AN-6.

steel1212 · Sep 14, 2005

Why couldn't he just run it where the old line went? I plan on doing the same thing this winter. Do I need it...probably not but like jay said...why starve?

19simmons65 · Sep 14, 2005

How difficult is it to run a fuel line?

rbohm · Sep 15, 2005

3/8" line will actually handle alot more than 400hp, closer to 600 or so as i recall. the only reason we ran 1/2" line on our fuel altered many years ago was because we were running alcohol and we needed the volume. we were making around 800hp.

as i recall 5/16" line will handle about 400hp before you start having starvation issues at the top end.

mdjay · Sep 15, 2005

This is funny timing. We're finding out right now that my 3/8" hard line is not sufficient enough for my set up. I'm running a #8 braided front to back today! I intend to follow the hard line route! The #8 is 7/16 so this should get more fuel volume there. The biggest problem with the hard line that I can see is the decreasing radius bends.

mustangdave · Sep 15, 2005

I plan on following the stock routing. I think steel line would be more resistant to damage on the street but I could be wrong. 3/8" will be plenty for my near stock setup or any mods I might make.
Mdjay, what kind of power are you pushing to need a bigger line? Is it f.i.?

monk302 · Sep 15, 2005

19simmons65 said:
How difficult is it to run a fuel line?

It is not difficult at all. I bought a roll of twenty foot 3/8ths from Summit. I already had a pipe bender for doing my brake lines. My experience is that shape the line at the rear first going to the fuel tank and then move forward.

dodgestang · Sep 15, 2005

mdjay said:
This is funny timing. We're finding out right now that my 3/8" hard line is not sufficient enough for my set up. I'm running a #8 braided front to back today! I intend to follow the hard line route! The #8 is 7/16 so this should get more fuel volume there. The biggest problem with the hard line that I can see is the decreasing radius bends.

I'm sure you covered this, but more than one person has been caught running larger fuel lines and then NOT remembering to increase the 5/16 line right at the tank or the size of the lines at their fuel pump also

67GTA-FB429 · Sep 15, 2005

mdjay said:
This is funny timing. We're finding out right now that my 3/8" hard line is not sufficient enough for my set up. I'm running a #8 braided front to back today! I intend to follow the hard line route! The #8 is 7/16 so this should get more fuel volume there. The biggest problem with the hard line that I can see is the decreasing radius bends.

So you used the driveline tunnel? What did you use to attach the tubing to the car? Didn't you bring it up over the rear of the engine (firewall) rather than out of the original location?

Edbert · Sep 15, 2005

I've always heard conflicting answers to this question myself. The only reason for such divergent answers that I can think of would be the pressure. I have heard that 400fwhp is the limit for 5/16 and 550 or so for 3/8 on a line with 4-6 PSI (carbureator). The mechanical versus electric is not the issue it is line pressure.

I put a 1/2 inch aluminum hard-line with some -8AN fittings and 1/2 braided lines; all behind a 110gph mechanical pump at 6psi...just to be sure.

mdjay · Sep 15, 2005

You can use frame clips or rubber insulated wiring loops.

My fuel pressure is much higher on mine. I'm using the carter provided by paxton which is 9lb at idle and it boosts references from there up to 12-14. The top end is where I'm having issues. Keep in mind this motor is no where near stock. 586 lift solid rolloer, big valves and lots of work on these aluminum heads. I'm still running the stock pulley on the paxton until I get all the bugs worked out. On the higher output motors, you definately need a vented gas cap at the least.

The other problem I ran into is if I have less than a 1/4 tank, the car pulls so hard that it moves the gas out of the way of the pick-up. Then I vapor lock!

ForceFed70 · Sep 15, 2005

mdjay said:
The other problem I ran into is if I have less than a 1/4 tank, the car pulls so hard that it moves the gas out of the way of the pick-up. Then I vapor lock!

Have you looked at using a surge tank? This is the easiest and cheapeast option but running 2 pumps kinda sucks. The only other option to fix this is to modify the fuel tank by adding baffels or a sump in the center with a new pickup.

mdjay · Sep 15, 2005

mustangdave said:
I plan on following the stock routing. I think steel line would be more resistant to damage on the street but I could be wrong. 3/8" will be plenty for my near stock setup or any mods I might make.
Mdjay, what kind of power are you pushing to need a bigger line? Is it f.i.?

I agree with the 3/8 on a mild build. I have a SC 302 with everything roller and openned way up. Somewhere between 550-600 crank hp (never bench dynoed) with about 457 on the ground. I'm only getting about 5-7 lbs of boost. I waiting on getting the bugs out and adding miles before I change the pulley. Don't ask me why I'm considering changing the pulley to their 10 lb upgrade, the damn thing is already too fast. I think it's the 500 rwhp goal that is pushing me. Click the link on my sig to get more specifics...

mdjay · Sep 15, 2005

70_Nitrous_Eater said:
Have you looked at using a surge tank? This is the easiest and cheapeast option but running 2 pumps kinda sucks. The only other option to fix this is to modify the fuel tank by adding baffels or a sump in the center with a new pickup.

I'm not that serious about racing this thing yet so it just makes me baby it if I get low on gas. That's a good thing. This car is more set up for the corners than a launch. Too stiff out back to squat. I just baby her first gear and let her rip in second gear.

ForceFed70 · Sep 15, 2005

mdjay said:
I'm not that serious about racing this thing yet so it just makes me baby it if I get low on gas. That's a good thing. This car is more set up for the corners than a launch. Too stiff out back to squat. I just baby her first gear and let her rip in second gear.

I would expect you to have the same sort of problems when cornering hard on a low tank.

It sounds like your still running a carb which probably helps. I know that alot of guys who convert their classics to EFI have the same problem. Carbs are much more forgiving when it comes to air in system.

If it does start to bother you, look into a surge tank. Easy and cheap to make.

67GTA-FB429 · Sep 15, 2005

dodgestang said:
I'm sure you covered this, but more than one person has been caught running larger fuel lines and then NOT remembering to increase the 5/16 line right at the tank or the size of the lines at their fuel pump also

So how would you increase the size of the line at the tank?

What size fuel line

mustangdave

My rearend needs a stud and two nuts.

ForceFed70

That's why they call it "dope"

mdjay

dodgestang

Active Member

67GTA-FB429

Member

steel1212

Active Member

19simmons65

New Member

rbohm

mdjay

mustangdave

My rearend needs a stud and two nuts.

monk302

dodgestang

Active Member

67GTA-FB429

Member

Edbert

mdjay

ForceFed70

That's why they call it "dope"

mdjay

mdjay

ForceFed70

That's why they call it "dope"

67GTA-FB429

Member

Similar threads

What size fuel line

My rearend needs a stud and two nuts.

That's why they call it "dope"

Active Member

Member

Active Member

New Member

My rearend needs a stud and two nuts.

Active Member

Member

That's why they call it "dope"

That's why they call it "dope"

Member

Similar threads

Privacy & Transparency

Privacy & Transparency