I recently purchased a procharger fed 383 with all the goodies from another member. He had a racetronix twin 255lph in tank fuel pump system activated by a hobb switch. The rest of the fuel system was bone stock aside from the fuel injectors (96lb.) From my understanding the stock lines are at their limit with this hp. I'm looking at making my own fuel system and have quite a few questions..

The fuel is going to be fed via twin 255 in tank pumps which I plan on making. The main pump will have a racetronix harness and the second pump will be activated via hobb switch at 5psi.

Fuel rails will be cut and an fittings will be welded on. I think a -8an feed and -6an return should be more than sufficent?

Since the feed line from the tank will be -8an will the factory feed line in the sending unit constrict the flow of fuel? How can I remove the factory steel line in the pump/sender unit and install a different line?

From reading through the forums I have found it is better to run the rails in parallel, do I put a Y fitting on the feed line and go into the back of each rail then Y fitting the return lines at the other end of the rail into the regulator?

Does the fuel pressure regulator need to be boost referenced?

Any input will be greatly appreciated!
Jason

 

Yes, the FPR needs to see vacuum and boost in order to maintain steady pressure drop across the injectors.

I would think the stock feed line could handle 700rwhp? maybe increase the pressure to 4 bar to help with flow through the line.

 

I saw 700rwhp with stock lines and regulator.

Rich

 

The guy I bought the setup from was using stock lines and regulator with a racetronix twin 255 pump system and it made 700rwhp so I know that it can be done. How much more room does the stock system have to grow though? While the car is apart I would rather spend a little extra and only do it once. What pump were you using when you saw 700?

 

I have a twin pump Walbro sending unit. I fabricated myself. I have some pics @...
http://s306.photobucket.com/albums/n.../fuel%20pumps/
Some details...
App... 97ss 383 D1 MM6 Moser 3.73:1 gear. Custom fabed (my own) with modified bulkhead plate.
No hobbs switch. Both pumps run continuous.
-8an feed/ -6an return.
User twin -6an feed from each pump to a Y in the old stock fuel filter location. Plumbed with AeroQuip socketless hose with all -an fittings. Hose is teflon lined.
-8an (1/2") alum hard line run @ the Y output up to the motor compartment. Some -8an Socketless hose also used there.
I have wired a switch for 2nd pump disable from the driver seat.
I also use a KBell BAP on pump #1.
No fuel bucket, and, hard cornering can starve pump #2, so, I can turn it off.
Series circuit with a boost ref type Aeroquip EFI regulator mounted off the diver side rail (not the small stock rail regulator).
I have had no fuel distribution problems with the series design feeding 72# Seimens peak/ hold injectors.
Hope this helps. B.

 

I made 800HP at the flywheel on nitrous, with a -6AN supply line, and a -6AN return line. A -6AN line is the same diameter as the stock fuel supply line.

Balance of the system:
-205 LPH Bosch pump in stock location
-2nd 205 LPH Bosch pump off a sump connection at the bottom/rear of the stock fuel tank.
-2nd pump only runs when nitrous system is activated
-10AN line from tank to 2nd pump.
-6AN line from each pump into an NOS -6AN wye. (check valve in line from outboard pump)
-6AN line to an SX billet filter
-6AN line from filter to back of engine, splitting through another NOS -6AN wye
-6AN line to fitting welded on the back of each rail
-6AN fitting welded to the cross-over pipe at the front of the rails, running back to a Weldon fuel pressure regulator under the cowl. Operating at 58psi (4 bar).
-6AN return line to the tank.
-fuel pressure gauge tap on passenger side rail.
-78# Bosch low impedance injectors

I am tuned without using the vacuum compensation line. It isn't necessary as long as tune keeping in mind that the fuel rail pressure is a constant, and intake manifold vacuum (or boost) is a variable. You just build it into the fuel tables.

 

I had a single Bosch 255lph in-tank pump and a Kenne Bell "Boost-a-Pump".

Rich

 

Thanks for all the input! I wish there was a clear cut way on how to do it.. I have now started to consider putting a sump on the tank and running a big inline pump, but more than likely I will be making a twin 255 pump system. Are there special electrical connectors and wiring designed to be submerged in gas?

 

A lot of us have done it with altered fuel rails and twin in-tank pumps and it works nicely. Special electrical connectors aren't needed but use good teflon or xlp wire, not pvc and use good SAE J30R10in-tank fuel line. Use big wire back from your battery or alternator and make a good ground near the sender. Also you can unsolder the fuel lines in the sender plate and replace them with 3/8 if you want because that 3/8 fuel line pinches down to 5/16 on the tank side of the plate. I made my plate with two 3/8 feeds and a 3/8 return made from steel tubing which you can buy and bend, then solder in there in place of the stockers if you want - its not that bad to do. Then you use hard line to AN adapters to braided lines. Y into your filter and -8 up front then Y into the rails and from the rails to the regulator, then back to the tank.

 

Over 730rwhp and have done what others have done...and proven.


dual walbro 255's, hobbs switch, 96lbs inj, Rails: Modified -8 feed (parallel) -6 return

 

im running duel intank walbros second one on a wot switch, aeromotive fpr, 60lbs injectors (almost maxed out) stock lines. just down 670 thru a th400 and big stall, so that prolly around 750-800 in a 6 speed! i think my setup with bigger injectors could see 1000! and were bout to find out!

 

I decided to go with the twin 255's in tank. As everyone else does I'm gonna put the Y in tank to a single -8 line going into the fuel filter then toward the engine bay. Only thing I can't figure out is the fuel pressure regulator.. What kind are you guys using? I was looking for a single in single out but couldn't find any name brand ones.. Are you running a return from the regulator? The tune that came with the setup was made using the stock regulator so I don't think I will need to build anything extra into the fuel tables, at least not to get the car running..

 

Weldon AFPR on the return line.

 

Thanks for the info! One more question.. What did you do with the evap system? Can it be deleted?

 

Yes, EVAP can be deleted. May notice a bit of fuel smell at the rear of the car, since the canister is no longer removing the HC's from the tank vent. Actually, with a tank full of C16, its a nice high....