What HP can a 3/8" supply line feed without problem?

[Samckitt]

How much horsepower can a 3/8" feed & 5/16" return line feed without problem?

[Hammered]

Up to 500HP from the info I've gathered. I have line sizing info on this page of my website: http://john.my67.net/efi.htm

[Doug F]

At 43 PSI "quite a bit". I wouldn't be scared to run 750HP or higher. I run 630 HP with all 3/8 (-6). I have less than 1 PSI drop with a Walbro pump from low flow to WOT. I'd rather have a little larger on the pump feed, -8 say. The return should be the same size as the feed, otherwise you might get some non-linearity in your regulator performance.

If you look at a lot of 2000HP EFI cars, they are running -8.

WHat you want to watch for is restrictive fittings, such as non-swept 90's, or banjo fittings.

[MonzaRacer]

I have pushed 500 to 600 with 3/8ths. I just ran a double rgulator set up we pushed 50 PSI to first regulator then backed it down to our line preasure then regulated that down if FPSI and reg 1 dropped we checked fuel system if we leaned out after that we upped the psi to engine feed and we kept a lot higher PSI on first reg as we pulled NOS fed from there too.On data log if it dropped on full booby run we would turn up the pump.
We had 1300 hp with (900 hp,300 port fogger and 100 plate and never failed to feed the engine)on a 3/8ths line and I hate 1/2 in aluminum line and a larger line requires more pump as the colum of fuel is larger and it takes more pump torque(re electricity ) to push a larger weight and this calls for a more charging system/batteries ,more money for bigger pumps etc.
I agree with the fittings and I dont use bras fittings I use compression fittings (the steel type) as they have less restrictive design and keep my bends as gentle as possible. I like the compression fittings that adapt steel line to AN fittings, very unrestrictive and it comes up clean and very safe as the steel line can handle LOTS of preasure.
They turn 600 to 700 hp out of LT Fbodies and never up grade the lines.
Good luck,
Lee Abel