just looking for opinions on the design of my fuel system. its going to be a -8 feed line from the pump forward, inline -8 filter good for 150 gph, up to a y block where it will split into (2) -6 lines, and go into the back of each of the fuel rails. at the other end of the rail it will exit in -6 and each will go into the regulator, and one -6 exit from the return line, the whole way back to the tank. im undecided about my engine yet, but i got a stupid cheap deal on a ton of fittings and hose so im gonna put this together for something to do. engine will either be around 500 hp n/a, or if i deciede to do the turbo i want about 700 at the whees. the pump is undecided also, either sump the stock tank and go A1000, or build a double pumper with (2) 255 pumps. i know both are good options just can decided that yet. would the way i have the lines plumbed in my head be enough to fuel either engine combo? thanks for any imput guys!

 

App... (97ss 383-D1 MM6).
I run two Walbo 255's in tank w/ modified fuel unit and bulkhead.
Each pump feeds a -6an Y located @ rear seat.
Single -8an to the motor compartment thru a fuel cooler and a filter.
Still running a series circuit with a remote boost/ ref fuel regulator.
My own design w/ parts from Summit. It's been doing the job well.
B.

 

so im guessing that your running a -6an return line? what kinda power do you make? thats pretty much what im thinking but id like to run the rails in parallel. thanks

 

Yes, -6an retun line from an Aeromotive regulator. I found that moving the reg off the rail allows for better fuel pressure distribution on cylinders 5 and 7. But, I agree, parallel fuel rails are a better fuel delivery circuit.
I have never dyno'ed the vehicle, but, it should have 700+hp @ the fly.

I went in thru the rear pan. Easy in/ out maintenance with the fuel pumps.
http://s306.photobucket.com/albums/nn244/mzgp5x/
I don't think I could go back to NA. The problem with FI is there are alot of changes to everything on the car. Expensive habit.

Best of luck. B.

 

ok thanks man, i just had one question about your fuel pump set up. from the pumps up to the bulkheads, what size hose is that? i was thinking that 5/16 was the only size that walbro pumps had for outlets... and what fitting is on the end of the bulkhead fittings? thanks alot man

 

Used an Aeroquip -6an socketless hose segment on each pump. Secured with a band clamp and a stainless wire tie back for axis force @ the pump output.
Used a -6an bulkhead fitting on each pump output line. Bulkhead fitting was a -6an male to male with a single 90* el.

I had to mount the pumps over/ under. You can starve top pump with low fuel and hard corner.
B.
http://s306.photobucket.com/albums/nn244/mzgp5x/

 

so the -6 socketless hose is basically 3/8 hose right? was i correct in saying the pump outlet was only 5/16? thanks for all the help man

 

Yes. a -6an hose ID is larger than 5/16. A loose fit on the Walbro male output barb fitting. So, a -6an can come off the barb fitting under load. That was the reason for a radial band clamp, and, an additional wire tie for logitudnal tube load from pump pressure. After 4+ years of Op, this mod (for me) has produced no further problems w/ the "hose OFF" failure.

The -6an PTFE Aerquip socketless hose is smooth/ straight bore teflon lined and fit well to std. -an bulkhead fittings w/ available from Summit. Thus, my approach/ selection in use of the -6an. I had to mod the attachment to the normal 5/16" walbro barb fitting to retain attachment.
I'm just throwing my approach out there. So, if NO like, throw out.

Also, I replaced the stock fuel delivery system w/ a combination of Socketless A_Qp hose and -8an hard aluminum.

You don't have to use. This was my result w/ the rolling experiment experience.
Hope this helps.
B.

 

cool, thanks for the help man. anyone else have any imput? thanks!

 

Just a couple of comments: Yes, the Walbro nipple is 5/16". It does present issues, as explained. The only true solution is to find something that acts as a 5/16" to 3/8" adapter. For the type of system described here, I have not seen one. The Racetronix double pump design does this, but it is nothing like the system mzgp5x implemented.
Second, if you want to convert from -AN to inches and back, each unit of -AN is 1/16". So a -6AN is 3/8, a -8AN is 1/2", etc.

 

i was pretty sure on the conversions, was just making sure. so what would be a way to adapt the 5/16 nipple to 3/8... the correct way?

 

The best way is to put the Y inside the tank. I am not saying my way is the "right way" but it is a way to prevent trying to attach a 3/8" hose to a 5/16" barb fitting. So, here goes:
I went down to Ace Hardware and picked up some brass fittings. They are the following, including part numbers:
5/16 barb 90-degree T 1/4 MPT fitting (2 required) – 47087
1/4 NPT female T fitting – 42049
1/4 MPT to 3/8 compression fitting – 43020
Hook them all together, and you have 2 5/16" barb fittings going into the T, and a 3/8" compression fitting going out. This compression fitting connects directly to the stock metal line inside the tank and will support 1000 hp N/A.
Do not be concerned about the 1/4 NPT fittings. I measured the inside diameter of the Walbro barb fitting, and the 1/4 NPT inside diameter is actually slightly larger.
If you want my entire writeup on putting dual Walbros in your tank, including pics, sources and part numbers, PM me your email address and I will send it to you.