Need fuel system oppinions!!
 

finishing my fuel system this weekend, 2x id1000 and 2x id2000 feeded with paralell an6 from dual bosch 044, so far so good.... but the problem is the lift pump, will a walbro 485lph do the job or will it choke the dual 044 (600lph), i will use an8 from walbro to splitter into dual an6 into 044's...
and will this suffice for 400rwhp on e85???

Either way will be enough for 400hp on E85, but you will have more headroom if you ever decide to increase hp goals with dual Bosch 044.

the 044 are Externaly mounted and i wanted to know if a walbro 485 is enough as a liftpump (prepump)...not whitch one to use :-) or did i misunderstand you? or are u suggesting dual 044 feeding dual 044

Oh i see, didn't see the part u were looking for a lift pump to feed the dual 044.

That's a good question, I will think that without a swirl tank you will be choking the dual pumps.

I would suggest a fuel surge tank between the lift pump (whatever you choose) and the dual Bosch 044's.

I'm assuming you are going to be running at least 20psi on E85...so with 43.5psi base pressure, that would be at least 63.5psi fuel pressure at full boost, not including line losses. At 65 psi and 14V, dual bosch 044 pumps flow ~575lph. This is what your lift pump will need to supply at 0psi (or say 10-20psi just to be safe). The Walbro 485 flows a maximum of 440lph at 0-20psi (at 13.5V however).

So at full tilt, the Walbro 485 won't provide the fuel needed for dual Bosch 044's at 20psi boost pressure and 43.5psi base fuel pressure. The better questions are do you actually need the flow capacity of dual 044's and is your surge tank big enough to not care about the difference in flow capacities?

From AMS

http://amsteam.net/files/8/fuelpumpgraph-3.JPG

From MAP

http://www.maperformance.com/product...lph-charts.jpg

Assuming you plumb the return from the high pressure circuit back into the surge tank, the Walbro lift pump only needs to supply the volume of fuel consumed by the engine in a steady state condition (as hinted above). It doesn't necessarily need to match the flow capacity of the dual -044s.

I don't like the idea of relying on the volume of fuel in the surge tank to compensate for a insufficient flow from the lift pump. If you face a situation where you're at WOT for an extended period of time, you'll eventually go lean.

So the question is: How much fuel will your engine consume at full power? Your lift pump needs to exceed that flow.

have you thought about just running dual intank pumps?

If you're going to go through all that trouble just do what I did and put 3 Bosch 044 pumps in the tank. Each one of my pumps feeds a separate fuel rail which activated as needed by the ECU.

thanks everyone! will try to mount the two bosch pumps in-tank!

Remember that the fuel pumps supplying the rails are pushing into a pressurized system and the one supplying the surge tank is pushing into a vented system.

I'd just run the two 044s intank and call it a day, way simpler and more than enough fuel for what you're running.

It doesn't matter. Since any fuel not consumed by the engine is returned to the surge tank. The surge tank needs to be replenished by the lift pump at a flow rate greater than what is consumed by the engine.

Let's take an example:

Pressure pumps total flow (worst case): 500 LPH

Engine total fuel consumption (worst case): 350 LPH

The pressure pumps will supply 500 LPH, but 150 LPH will return to the surge tank. The net fuel consumption is only 350 LPH.

The lift pump must supply more than 350 LPH to keep the surge tank full, not 500 LPH.