how much horsepower can a 3/8 diamerter support at 4-6 psi on gas?

between 4 and 500 BUT the pump has to be able to produce the volume vs time ( gals per min ) that the motor is going to use... which, for the sake of discussion is generally something more than 60 gal per hr.

in the end, people talk about using 1/2 to be safe all the time which i suppose is cheap insurance.

No More Than 450 Hp.

Look at what Merc uses for their 600's....3/8".

I'm using 3/8" on 650's....Stock Merc (HP500) pump..NO Problems.

Dave

I am using -6 line (3/8') on 780 HP and hold 5.5-6.0 lbs at WOT.
If you figure a 3/8 line will flow approx 60 GPH, then a 3/8 line will support 800+ HP at .5 lbs per HP per hr.
If you can easily re-rig with 1/2" line, I suggest it so you won't have to listen to the chatter on OSO that it won't work

My 525SC had 3/8 and was bumped up to 550hp+ and had no issues.
I would also get a pump that will keep fuel psi at 6-7#

thanks for all the input.it gives me food 4 thought on a problem i have had for a long time.