Fuel Line size for V8

[deMideon]

I am at the point of getting fuel line... I have a fuel cell so that is taken care of, so now I need to know what size line to get. I am going to be running about 450hp, but I want to make sure the line will support 600... cause ya never know what I will do to it down the road So what size is good? 1/2" is what I am thinking. What are your opinions? Also where is a good place to get it? Thanks!!!

[Pyro]

Before I did any fuel system upgrades on my V8 Z, I got by with the stock 240 fuel lines (5/16"). At that time, I was using a mallory 110 pump and a 750 Holley carb. I was running low 12's at 115 (400 hp) with that setup. Then I installed a 3/8 feed line welded into the factory tank and a better set of heads and exhaust and ran mid 11's at 120 mph. Then I installed a 1 gallon fuel cell by the radiator and used a comp 70 pump on a 175 shot of N20. I would use racing fuel in the 1 gallon fuel cell. My car ran mid 10's at over 130 mph with that setup. So if you are going to run N20 then two fuel pumps and two feed line might be a good idea.

 

Now, I have a fuel cell with 1/2" feed and return lines, a return style fuel pressure regulator, and a Mallory 140 pump. When I first installed the bigger lines, I used a comp 250 pump but the pump made too much noise for my taste. However, I think the comp 140 is a little too small for 600 hp. But that comp 250 was LOUD!

 

The size needed will also depend on what fuel pressure you use (carb or injected). You will get more flow through a fuel line at higher pressures. The comp 140 and comp 250 mallory both run at 14psi. A high pressure fuel injection pump will flow even more volume through the same size fuel line.

 

So, I think 3/8 should do it but 1/2 will be safer. FYI, 1/2" lines were a pain to run. If I had to do it over again I would run two 3/8 lines. And, if you use a return line system then the return needs to be the same size or larger than the feed line.

[Guest Big Geek]

While the V-8 was in my 240 I used 2 #8 Russell feed lines with two 90-degree fitttings from the cell(One for the motor and one for the N2O.) and a #6 for the return. I was using Holley Blues but they are noisy. While spraying it I never saw the FP drop below 5-lbs under full throttle. I hope this helps some. Cheers !!!

 

Jim C.

[Guest Grenade300]

This is probibly a dumb question, but I have never messed with the fuel systems on my cars. What is purpose the fuel return line?

[Phantom]

Fuel Return Line: Many fuel injected cars use a fuel pressure regulator that "bypasses" fuel to maintain the proper downstream pressure. This "bypassed" fuel is sent back to the fuel tank via the "return" line.

 

Now - My LS1 V-8 that is currently running about 365 HP is using the stock AN6 (3/8") fuel line. An AN8 (1/2") line would flow about 75% more fuel so it should be plenty big enough for your application, depending on the pressure rating of the fuel pump you select.

[deMideon]

Thanks everyone for the replies! I guess I will think about this a little more... I would hate to have to run a 1/2" back for the return, I figured I would be able to use the 3/8" stock one for that.... hmmmm.

[Guest Grenade300]

Thanks for the info Phantom. I used to think that I know a lot about cars, but the more I learn, the more I realize that I really don't know that much especially the simple things.

[Scottie-GNZ]

Just a tad over 500RWHP and I run a fuel cell with a short -10 feed to a SX pump/filter assembly at the side of the cell, then -8 out of the pump to the fuel rail. On the return side I run -6 from the rail to the firewall where I connect it to the stock 240Z feed line.

 

HTH,