dave I think you're right...i cant remember the exact diameter but that sounds close....
as far as staying under a certain powerlevel, lol, he wont have the choice but to stay under the maximum possible hp supported by the lines
if i were to take a stab at this from a realistic situation i would say that you would run out of injector before you run out of line in your car.
the reason i say so is that the cost of upgrading injectors (past the regular 525's we can drop in) is much more significant than running an extra pump
and another line. I just ran another -8an line along the stock line. Each line is fed by an in-tank walbro 255hp (makes me want to puke that im still running these things....) pumps and i have a dual feed to my boostlogic fuel rail which feeds the 1000'cc injectors.
if i remember correctly when i had my car tuned on the old set up with the 525's my injector duty cycle was at about 90% making 450rwhp on pump on a hot day. keep in mind thought that htis was with the crappy fuel-pressure-regulator so i could have easily squezed out more power from both the lines and the injectors. But i would think that around the 500rwhp mark both of the factors would become the limiting ones just about at the same point
Well I have 630cc injectors. I have a single feed FSmoto rail.id like to make 550whp if I can on the stock lines if I can just want to know. I really don't want to have to add another pump I wana keep it simple and make some nice power but idk ill have to see how I can run dual pumps on a single feed.
If the stock stock hard lines are 3/8th inch diameter (-6AN standard), it will work fine for ~190 Gallons Per Hour flow IF you're PUSHing fuel through them with a fuel pump inside the tank. (credit: T1 Race Development) The stock lines only become more restrictive when you try to PULL fuel from the gas tank via external fuel pumps, etc. Measuring the diameter of the fuel pump pickup hard-line inside a Lexus SC300's gas tank, I saw 3/8th inch diameter. Thus, a 3/8 inch diameter fuel hard line is fine for 1,000+ whp on ethanol if you're pushing fuel through it. Just make sure the fuel pump can flow that volume and handle any pressure drop .
yes, I believe a stock 3/8 inch diameter fuel feed hard line is not an "upgrade-worthy" restriction when using a high-flow in-tank fuel pump for most of our power goals. Since I'm using a fuel pump that allows PWM control of its speed (volume flow), I'm retaining the stock return line as well. Whether the oem fuel hard line path becomes smaller diameter in some sections, I don't know. But, my test results will go public when it's done...always learning .
Im very interested to hear more. I'm planning on pushing two pumps in tank. Then have them come together to one -8an line. But if I can push enough fuel for 700whp t on stock hard lines then ill jus use them.
FWIW, the hard line is sized for a -5AN line. This comes from direct experience after removing the rubber feedline, cutting and flaring the hardline and installing the flared -5 fitting and nut. A -6 flared fitting and nut are too big.