I've read through this site and the chevytalk EFI forum, and thought that I had made up my mind to order two 3/8 inch prebent hardlines for supply and return lines for the '65. It will one day (crosses fingers and makes a wish) be an EFI 383 powered street car-little if any track time-so I'm not looking for every last HP, just a strong, fun car. BUT, I just read an article in the July 06 Chevy High Performance describing EFI plumbing that says "...you'll want to use at least AN-8 line (1/2-inch id)...more power than 600 horses consider AN-10." Seems like overkill to me, but I wanted to check with you good folks before I whip out the credit card. Do I need to step up to 1/2 inch lines? I don't think the cost is much higher especially once you consider the money that will be spent overall; I'm asking more from an advice/"why do I need to" angle and also I'm just trying to learn more without making too many mistakes.

Thanks for any input.

At 43 PSI you don't need lines that you would with a 7 psi carb setup. I've seen 2000 HP EFI engines with -8, several times. Go bigger on the inlet of the pump if anywhere.

I'm -6 all they way with my current engines and have seen no pressure problems so far.

Magazine articles try to sell......

Aeromotive does reccomend very large lines, I think it is way overkill.

DO stay away from sharp 90's and small orifices. They will cause problems.

Lines for EFI dont need to be nearly as big as low PSI carb setups. It is very similar to electricity and wires, higher voltage (higher pressure) requires less wire diameter for a given wattage (gallons per hour).

I have worked on a couple of blown/EFI small blocks that made 900+hp on a 3/8 fuel line. anything over 1/2" is overkill for under 1300-1500 hp.

Yeah, I have to agree with what's been said. I have a Weldon fuel system, and they have me set-up with a -10 feed and return line (-12 from the fuel cell to the pump) but my set up is built to support 1800 HP. Weldon uses the same size fuel lines on cars making well over 2000 HP the only difference is a bigger pump.

Rob