5/16 Fuel lines with LS Motor

[GBPCAZ]

The 5/16" fuel lines supplied with the kit seem too small to handle an LS Motor. The GM OE lines are all 3/8". I'm thinking of upsizing but some of the fitting supplied with the EFI Kit choke the flow down to barely 1/4". Any suggestions?

[GoDadGo]

I'm NOT running an E.F.I. set up; however, I was able to get a 3/8" pick up via my local NAPA auto parts store since a friend of mine manages it. We ordered all the different Mustang pick up part numbers to see what would show up and found that we had a Winner, Winner Chicken Dinner moment. I ran the 3/8" feed line, since I'm running a mechanical pump, but didn't need to run a return line since my system is Stupid Simple compared to yours.

My suggestion would be to contact Mark Reynolds at Breeze Automotive because I'm sure he'll have a solution for you, especially if your pump is externally mounted.

His link below may be of some help to you:

https://www.breezeautomotive.com/?s=...t_type=product

Good Luck Fellow Dark Sider!

[cgundermann]

I had that same concern for my EFI (multiport) 347 and called FFR. They said they are running 5/16 lines on their EFI 500 horse 363 SBF. They indicated 500 horse is the upper threshold for 5/16 lines. The smaller lines for EFI run a much higher pressure compared to the lower pressure larger volume mechanical lines.

Do not know what your LS motor is putting out for power, but my 450 horse 347 with 5/16 lines runs just fine.

Chris

[GBPCAZ]

Thanks for the info. I'm not planning on over 400HP. Aging out of insane power to weight ratios!

[HVACMAN]

I have the 376/480 which is 495 hp. I bought 3/8 steel lines for the supply and used the 5/16 lines for the purge canister.