I wanted to use an intank pump system

I am running the rails parallel with a -6 return/reg set-up.

need to figure out if I should run -8 or -10 to the feed and y-fitting. Also how should I adapt the feed to the line in the tank?

Its 3/8" coming out...won't this be a restriction?

or maybe I am on the wrong track all together and need a cell and another pump etc.....?? engine should make around 600 or so flywheel

Not sure if the intank 255 is going to work or not, if I need to go another route recomend something.....I'm lost

 

 

I made 700rwhp with stock lines in a prior iteration.

Rich

 

I got pics of dual intank pump mod but z28 message reply will not let me insert image. Two (2) -6an fual line Y outside the tank. Sorry. Maybe e_mail. B. User803815@aol

 

Rich what pump set-up were you using? I went with a union and -8 to the front a magna fuel Y and -8 to each rail

 

I'm making 800HP with a -6AN feed line, -6AN return line. The -6AN feed line splits at the firewall, through an NOS -6AN Y, with a separate -6AN line into the back of each rail.

 

At that time I was using a 255LPH Bosch in-tank and a ""Boost-a-Pump" from Kenne Bell.

Rich

 

How would two -4 AN lines from the front of the fuel rails into the regulator with a -6 out to the factory return line work? Would the -4's be too much of a restriction? I am planning to feed the back of the rails with -6 lines coming off a y fed with a -8 from the filter.

 

The "nominal" outside diameter of AN tubing is the AN size/16.... a -4AN = 4/16 = 0.25". But pressure loss depends on the inside diameter of the tubing. Russell lists the inside tube diameters:

-4AN = 7/32 = 0.219"

-6AN = 11/32 = 0.344"

Recognizing that the area available is proportional to the diameter squared, two -4AN lines will only have the equivalent open area of about 80% of a single -6AN line. And the dual lines have more wetted perimeter, which also increases pressure loss. Bottom line... 2 -4AN lines are not as good as a single -6AN line.

Whether that is an issue is open to debate. But the objective of the fuel pressure regulator is to hold the pressure in the rails as close to a constant value as it possibly can, for uniformity of performance. Directionally, you will want to minimize the pressure loss between the rails and the FPR, so this is case where "bigger is better". The shorter the lines from the rails to the FPR, the less important it becomes.

 

So would -4 lines coming out of the top front of the fuel rails and then into a dual inlet regulator at the back of the intake cause a problem? I would use -6 from the reg to the factory return line. The -4 lines with this configuration would only be about 12" long. I could even place the reg farther forward on top of the manifold to make them even shorter.

In thinking how a bypass type regulator works, it would seem that at times of high fuel demand, the reg restricts the amount of fuel returning to the tank in order to maintain pressure making the small lines a non-factor. So is it a matter of having enough avalible fuel flow through the reg to avoid pressure spikes during high transient flow demand?

 

^^ I used to have mine like that....I had 2 -06 into a reg and someone makes a tube adapter for a 5/16" hardline so I tied it to the factory return line.


I wouldn't bother with the -4

 

I'm rebuilding a sending unit for 2 in-tank pumps with all 3/8 lines - 2 x 3/8 feed (one for each pump) and 1 x 3/8 return and the 3/8 vent line. I took all the old tubes out and have the new tubes bent and almost ready to solder in. It'll be a while til it's done cause I'm working on it peacemeal and not in a hurry - I only need to work out details of how exactly I'm going to connect the two pumps - also I need to buy the pumps and hoses still. My plan is to run 2 -8 teflon lines to a tee at the filter and -8 all the way up to the rails - tee into each rail and then back to the regulator and -8 back to the tank. The reason for all the -8 line is that I have about 50' of the steel braided teflon -8 line already, so I'm trying to use that with adapters where possible and avoid the rubber lined hose altogether.

 

I would use -6 if I were starting from scratch, but I picked up some rails with the -4 fittings already welded in (I was hoping they were -6) so I am just trying to figure out if they will sufice or if I should re-work them with -6 fittings.

Any other thoughts?

 

Did dual (2) Walbro 255lph intank pumps on a 97ss. Fabbed a new tank bulk-head plate with 2 fuel pump outlets (-6an) with socketless Aeroquip hose & connectors (low cost from Summit). Single Y @ the old fuel filter location with -8an line to the motor compartment. Easy to remove pumps with the rear floor pan door option. I have seen some pics of the racetronix Y in the tank. Alot of flow restriction with that configuration, and, each pump can cause a dead-head on the other with down-stream pressure variance caused by the fuel tank return regulator operation. B.