Fuel ?- intank Walbro 340 and external Bosch 286 on a Hobbs... is this a good setup?

[gnx7]

I am stepping up to the plate and installing a T-70BB, 72's, LS1 MAF with Trans+, PTE-218R flat tappet cam, and PTE ported iron heads with ported intake.

Car currently has a Walbro 340 intank pump plumbed into 3/8" hi pressure fuel line and then into a Morosso "Y" block with one side capped (for future additional pump) and then -8 line to a -8 fuel filter and then -8AN to the fuel rail. I've heard this is good for around 600hp+ flywheel hp via PTE's fuel pump tests when hot wired.

The plan is to run the 340 and then have the Bosch 286 pump (external mounted) come on via a Hobbs switch at 15-17psi to run in conjunction with the 340 to meet my fueling needs.

When the 2nd pump (Bosch) turns on will this flood the motor with too much fuel or make chip tuning a nightmare? I'd heard this from a few people... but not real proof to back it up.

This is my plan as I have the Bosch pump already.

All comments welcomed. I want to do this right... don't have room for a double pumper setup in my car.

-GNX7

 

[Lee Thompson]

pump

I have this exact setup and have been running it for 10 years. NO problem with bring it on at 15 plus boost. If I cross over the hobbs switch at idle, the fuel pressure will go up 10 psi, but doing it at WOT there is not spike. IMO this will work fine for you. I guess the HOT setup now is either one large pump or a double pumper. ( A double pumper does what you will be doing, just all in the tank)

 

[DR BOOST]

DOUBLE PUMPS

i have the exact same setup as you gnx7 but i run -10 to the rail from the y block.

if you are running the bosch pump inline with the otherpump, then i dont think its really worth doing.

if you use the bosch pump with its own seperate pickup, remember that the bosch pump doesnt have a check valve in it.
so , the bosch pump needs to be the primary pump, and the walbro secondary.

if you upgrade the return line to -6, then you dont need the hobb switch and you can turn the pump on and off when ever you want. the small diameter of the return cant handle the volume produced by two pumps, thus the pressure goes up.


hth

surej

 

[gnx7]

thanks for the reply guys.

The Bosch pump will have its own 3/8" pickup and then goes into the Morosso "Y" block and -8AN to the rail.

I have -6AN return line going back into the stock feed line (switched at the gas tank). I know the fuel pressure spike problem was due to inadequate return flow.... but at WOT I hope to be consuming most of it .

Lee- my friend ran (2) Bosch 286 pumps with separate pickups and 2nd one activated via a Hobbs switch. I hope to achieve similar results.... (700hp+).

Thanks again for confirming that it should work fine. Proof is in the pudding so I'll just have to find out for myself if my return flow will suffice.

-GNX7