Return line pressure

[CTX-SLPR]

Howdy,

Well I just discovered my first real setback (ok its a small one) the return line off the regulator is 5/16in, the return line on the car is 1/4in. Since the return line has almost no restriction to it, is it under any significant pressure? I need to change rubber hose sizes somewhere and since I'm going to change the hardline size in the future anyway I don't want to make it look pretty, just functional. I was just thinking steel adapter with EFI hose clamps, am I safe?

Thanks,

[BBR]

Re: Return line pressure

That will work fine.

[CDMBill]

Re: Return line pressure

I've read in a number of places including the Aeromotive site that return lines on high performance EFI applications should be at least as big or bigger than the supply line. As I understand it, the goal is to have in effect zero pressure after the regulator or your effective fuel pressure reading may be false as a restrictive return line will build pressure on the back side of the resistance spring in the regulator.

I am not sure how true this is or could be because I increased my return line to #10 to match my supply line based on that information and I haven't seen this validated by the experts on this board. It seems the issue would be more pronounced at low rpm and load as that is when the most fuel will be bypassed.

[CTX-SLPR]

Re: Return line pressure

Well I'm going to be changing the supply and return later when I go to SS line and it'll be a 1/2in supply and 3/8in return. Right now I'm going to be running a max of 10psi of boost and a stock Impala SS pump. Pretty sure this will be adequate for the time being till I up the boost and need more fuel.

[shaun callaway]

Re: Return line pressure

unless your too small on the return line there is usually no pressure just velocity.

for a low to mid hp range car i usually go with a 3/8 line and havent had any issues. i always use a 3/8 supply aswell. then when you start getting into the high hp thats when you need to address your supply and return but keeping both the same is usually just fine.

one thing that i have found usefull is that you make sure your return fuel is not dropping in over your pick up. this only applies if you are doing an install on a tank that was not equipped with a return line already.

[CTX-SLPR]

Re: Return line pressure

Ok, I got it solved with the help of Ace Hardware with a male-female pair of 1/4in NPT barbed fittings. Just double checked my tank line too and its a 5/16 so I'll have to get another pair soon. However, I'm not planning on changing the original pushlock fuel line fittings, will these work on my 3/8 and 5/16 GM fuel line tubes:

http://store.summitracing.com/egnsearch.asp?N=700+115+4294734134

Thanks,