Fuel line material...

[aarvig]

Aluminum, steel, copper/nickel, stainless...which material is the best for fuel lines and why? Looking at making some fuel lines and I know SS is a bear to deal with, steel is also difficult but aluminum and copper/nickel are easy to bend and shape. Any issues with them?

[RoadRacer]

Last time (non-FFR) I ran 1/2" aluminum hardline so I never had to worry about not flowing enough fuel. It was easy to form and flare.

[edwardb]

Personally, I would stay away from aluminum tubing. Many will say it's OK (used on aircraft, etc.) but it has the potential to work harden and break/crack if not supported properly. Also maybe not the best for compression fittings, clamps, etc. since it's relatively soft. There are other choices that aren't that much harder to use so personally I wouldn't. Any of the other three would be fine. Agreed SS is the hardest to work with. But if using the proper annealed material and good bending and flaring tools, it's doable. I've used it twice. But for no good reasons really other than I like the final look and it will last indefinitely. Steel is not hard to work with or flare, again if using a good flaring tool. Many like the cunifer (copper nickel) for brake lines. I don't recall seeing any builds using it for fuel lines. But it's rated for that purpose as well.

[Jim1855]

I'm interested in this as well.

My question is what size? My previous car, a Superformance, had steel 3/8" lines. Never had a problems at 550hp but always wondered if bigger would be better.

Jim

[DaveS53]

I chose to use -6AN stainless steel braided teflon hose ($5 per foot at Summit Racing) and -6 AN fittings for a 430 hp LS3, with 58 psi electric fuel pump.

[aarvig]

My engine builder, Smeding Performance, in Texas, built me a 607hp 427w and told me to go no bigger than 3/8 inch line. Fuel flow and pressure are regulated anyway by the mechanical fuel pump. You could put a 3 inch pipe on the fuel tank and the carb will only be able to handle so much before it blows past the needle and floods the bowl.

[RoadRacer]

My engine builder, Smeding Performance, in Texas, built me a 607hp 427w and told me to go no bigger than 3/8 inch line. Fuel flow and pressure are regulated anyway by the mechanical fuel pump. You could put a 3 inch pipe on the fuel tank and the carb will only be able to handle so much before it blows past the needle and floods the bowl.

I'd rather have a big fuel line and rely on a pressure regulator than need to replace the line after a motor upgrade - anyway OP didn't mention mechanical pump or carb

I was running 3 fuel tanks and 2 electric pumps on that car, and had them both running when racing. In the '33 I'll probably be using the supplied parts (5/16?)..

[mikeinatlanta]

700hp 432 small block. 1,200 cfm throttle body injection.
1/2" nickel copper pressure. Rated to 6,000psi
3/8" 300psi pressure rated aluminum return (not the cheap crap from summit).

[GoDadGo]

3/8" steel >>>-------> Nothing Fancy, Keeping It All Super Simple With "Form" Always Following Function!

[Boydster]

I did copper nickel front to rear, 3/8 for an injected 427W. Earls braided -6AN hoses front and rear. Hasnt been started yet, but I liked the ease of manufacture and the fact that they will never rust.

[CraigS]

I did copper nickel front to rear, 3/8 for an injected 427W. Earls braided -6AN hoses front and rear. Hasnt been started yet, but I liked the ease of manufacture and the fact that they will never rust.

I agree. I recently tried ni-cop from Advance for a couple of brake lines. Really easy to work with. They have it in sections or in a 25 ft roll.

[CDXXVII]

I use stainless hard line for brake and fuel lines. Stainless is not hard to work with if you have the right tools. Stainless Teflon Hose for final connections on the fuel lines.

[Frank Messina]

Nice work CD. For fuel lines the simple rule is hard line for the long runs and flexible line for the short end runs that are subject to vibration and/or movement. Following that protocol aluminum line is as serviceable as anything else but personal preference wins on that decision. As for line size, some manufacturers of return style fuel pressure regulators call for the return line to be larger than the supply line. So... that 1/2" ( -8 ) line you were going to use for supply just became your return line with a 3/8 (-6) supply. Sounds weird but it works. Actually 3/8 is more than enough to feed just about anything but the most outrageous race motor.
Frank

[johnnybgoode]

I chose to use -6AN stainless steel braided teflon hose ($5 per foot at Summit Racing) and -6 AN fittings for a 430 hp LS3, with 58 psi electric fuel pump.

2X on SS 6AN teflon hose. Easy to install and works fine with a low pressure carb setup. Scott

[DaveS53]

I started out with the idea of using aluminum tube for the one long run, but later realized that it would be much easier to just use the braided hose for the whole thing. With a conventional frame, no sharp bends were needed so the entire line from the pump to the engine is one piece. The return from the filter/regulator is only about 1 foot long and the same -6 size as the rest. I probably used about 8 stainless clamps along the line. I drilled and tapped 10-32 threads into the frame for each clamp. I made a support bracket attached to the valve cover, that insures the quick disconnect fitting at the fuel rail is not stressed and can't come loose.

You can now buy in tank fuel pumps that totally eliminate the return line.

If using a regulator with a return, I wouldn't place it so it required a full length return line. There should be no reason to have a return line larger than the supply.

[Avalanche325]

Use steel, or stainless steel (if you want to make it shiny) hard line. Stainless will require serious tools. Even 3/8" steel is too much for those cheapo flair tools.
Aluminum is not tough enough. The flares are prone to cracking. I ran AL from my fuel pump to carb. A flare cracked and left me for a roadside repair.
Flex line should be used as little as possible. The only place you need it is from the frame to the engine. Everyone calls them "Stainless steel flex hoses". They are really rubber or Teflon hoses with a braided cover. They are tough enough for abrasion, debris, etc. The problem is from the inside out. They are a wear item and should be replaced periodically.
Cunifer is another option. Easy to bend. I have never used it.

From my research. 5/16" is good for around 400hp, 3/8" will get you to about 600hp. Then you need 1/2" and a big set of cajonies.

[DaveS53]

I disagree about the PTFE hose with stainless steel braided cover being a wear item that needs periodic replacement, unless the period is something like 10-20 years.

PTFE has an excellent rating for resistance to both gasoline and ethanol - better than any hose used on a production car. -6 hose has an ID of 3/8" so it's a a little larger than 3/8" tube.

It's also great for transmission fluid or motor oil cooling lines.

https://www.summitracing.com/parts/sum-230620

If aluminum tubing is used, there is no need to use a single flare. Compression fittings are available to convert from tube size to AN hose.

https://www.summitracing.com/parts/s...077b/overview/