customblackbird

iTrader: (15)

521cuin big block ford engine swap. Using stock tank, walbro 255lph high pressure pump. Going to have to run new fuel lines from the tank back. I should be in the 550-600hp range Naturally aspirated. I was told i could run a bypass type fuel regulator to bring the pressure down to 4.5-9psi for a carb application which is what im going to do. The walbro 255lph high pressure pump is good for 800hp but Im unsure what HP its rated for at carb like pressures?

heres the regulator Im going to run
http://www.summitracing.com/parts/PFS-10653/

I was planning to run -6an from the stock lines on the fuel tank to the regulator since the regulator has 3/8" NPT fittings, so there would be no point in running a -8an line since it would be bottle necked at the tank and regulator. I guess what im saying would the walbro pump at 4.5-9psi be able to support 600hp with -6an/ 3/8" lines?

customblackbird

iTrader: (15)

no one?

Apeiron

Are you going to use hose or tube?

Remember pipes are specified by I.D. and AN fittings by O.D., so 3/8" pipe is about equivalent to -8 AN, just a little bit smaller.

customblackbird

iTrader: (15)

what do u mean? do you mean that the -6an line is not the same size as 3/8" hard line?

I was planning on running AN braided line but that would mean i would need to run -8an? since your saying the ID size is the same as 3/8" hard line?

The stock tank has 3/8" hard line so thats my limit as far as bottle neck. I would want the line to support whatever HP i run which will be in the 550-600hp range without NOS and i will prob run a 100-150shot. so do I run 3/8" hard line again to the firewall? then -6AN or -8AN line to the regulator/carb? Or do i have to increase the line size to a -8an from the tank to the carb? i just dont see the point when the tank already has 3/8" hard line coming out so upgrading to 1/2" line would serve no real point i guess.

Im tryin to do this as cheap as possible! Dnt care about looks as much.

customblackbird

iTrader: (15)

bump

Apeiron

The size of a -6 AN line is derived from a thin-walled tube which has an O.D. of 3/8". The I.D. of the tube is something like .340" or so.

The size of the 3/8" NPT fitting is from a thick-walled pipe with an I.D. of 3/8", which is .375", so the "same size" pipe fitting is slightly larger.

A -8 AN line has an interior diameter of about .435", which usually works out to a better match with 3/8" NPT. Having a couple of 3/8" NPT fittings won't present much of a restriction.

The rear-mounted Walbro pump shouldn't have any problem developing enough head pressure to drive the volume you need through 3/8" line, and a with a front-mounted regulator you won't have to worry about line loss. If you were using a front-mounted mechanical pump, it would be a different case.

Even still I'd probably be tempted to run -8, anyway just to be sure that it wouldn't have to be upgraded in the future.

xpndbl3

iTrader: (5)

i wouldn't run that cheap regulator, stay away from professional product stuff. Buy aeromotive, magnafuel or the like.


Also run -8 front to back, that pump will definitely want -8 for a return since it'll be bleeding off a lot of pressure/volume with the carb setup at an idle instead of high pressure like EFI systems. Makes no sense to run a -6 feed to later need to upgrade if power levels increase.

customblackbird

iTrader: (15)

hmm ok i got ya. so steel 3/8" hard line like from summit has a 3/8" outer DIA, and due to the thickness of the tubing the 3/8" is actually smaller therefore diminishing the fuel capacity. So 3/8" line would be adequate for my HP goal but going much above that and i will have to upgrade to -8an. So i might as well upgrade now instead of purchasing the line all over again... unless the 3/8" line would support 550-600hp NA with a 100-150shot of NOS? Or would i need the -8an line bc of the nitrous?

1.) Fuel filter... im running a stock type filter now within 24" of the pressure line from the tank... Do I have to run the filter on a carb setup with the EFI pump this close or can I run it in the engine compartment?

2.) Will running -8an line after the stock 3/8" hard line coming out of the fuel tank even be possible? will the 3/8" hard line negate the point of running the -8an line bc its smaller and already creates a bottle neck? Also the stock return line at the tank is 5/16" which is much smaller than a -8an... so how would i do this? Im not really wanting to sump the tank since i would have to then purchase a different fuel pump etc which would kill the budget aspect of the build.

3.) how would you run -8an line from the stock 3/8" hard line, i can only find fittings that go from 3/8" to -6an. I havent seen anything for -8an.

4.) i agree professional products might be cheap but Ive used many products from them including 3 balancers, one 58mm TB, a crosswind intake, and some other miscellaneous stuff and they all worked great. I can not find an EFI to carb regulator made by anyone else tho, so if u got a part # then post it please. Ive used holley stuff and had to throw it away, my brother as well.

fast82z

iTrader: (1)

1) I wouldn't worry about the filter, just have one on there and call it good enough.

2) If you're going to take the time to put a -8AN (1/2") supply and return, which would be the smart thing to do to provide some growth room, I'd say you have to make it all the way that size. You or someone could weld and/or braze some larger line into the stock sending unit.

3) I used 1/2" copper (stuff used for home water plumbing) for most of the line in mine which was nice with the tight angles the fittings can make. Also, this line is actually bigger than 1/2" even on the inside, and to convert to a hose or thread on the ends you can soldier on a 1/2" or 3/8" NPT.

4) You don't need an EFI to carb. conversion regulator, just one that has a return line involved with it and uses at least 3/8"NPT fittings. The one you selected fits the bill fine although there are probably cheaper ones out there, I believe I've seen some around $35 or so.

customblackbird

iTrader: (15)

ok thanks. Ive never heard of someone using copper line before lol... thats not something i would have thought off. kinda interesting to see that it works. are you running EFI or carb? looks like u got a fuel rail in your pic.

well do you have a part # for that regulator? Ive been looking at return style regulators... but theres gotta be a reason professional products says that this is used for EFI pumps on carbed applications.

I measured the 3/8" line i just pulled off the car. heres the DIA's and theyre larger than i thought (used dial caliper)
OUTER DIA= 0.470"
INNER DIA= 0.410"
overall tube thickness= .030".

how is this possible when the line is 3/8" lol... it should be outer DIA .375".

Apeiron

Copper won't be allowed at the track, IIRC.

customblackbird

iTrader: (15)

i wouldnt think it would. Still tho... the 3/8" line is much larger than 3/8" apparently.

Apeiron

Sure it wasn't .370" and .310"?

fast82z

iTrader: (1)

The regulator I'm using is an aeromotive that comes with a spring for carb pressures, and a spring for fuel injection pressures and I have used both. The regulator is this: http://www.summitracing.com/parts/AEI-13301/

customblackbird

iTrader: (15)

sry your correct, it was .315" ID and .370" OD.

customblackbird

iTrader: (15)

I was looking at that regulator... thriple outlets means i would have to plug 2 of them. hows the regulator been working for u?

fast82z

iTrader: (1)

The regulator has and is working just as it should. I've always used it in a boosted combo which requires a rise in fuel pressure to go along with the increase of manifold pressure, and it's actually a little better than the 1:1 ratio they advertise meaning that it actually adds a little more than a psi of fuel pressure for every psi of boost. The regulator basically has 4 ports on the pressure side and a return line, so one of the pressure ports is the inlet and any of the other 3 are outlets. Plugging an extra port isn't anything spectacular, just a 3/8" pipe plug of any sort works.

When I had it with the carb. I had 2 of the outlets with barb fittings so each fuel bowl had its own 3/8" supply line and the third port used for a fuel pressure sensor/gauge. It's basically the same with the fuel injection, just that I use the stiffer spring for 60psi of fuel pressure instead of the carbs. 5-8psi and the regulator is mounted inline on the fuel rail(s).