What I'm asking is, has anyone made a double pumper using 2 of the 450/267 E85 pumps?

 

yes

 

Yes, my buddy nick has made and sold a few of his 450 double pumpers. He's still managing to run out of fuel around 740hp MD though.

 

Nice!

 

This isn't a factor of fuel pump capacity. Something else in the system isn't up to snuff.

 

+1

 

I have just installed one of the E85 pumps on a car. Had serious fuel pressure drop off under load. Spent/wasted some time diagnosing issues. What I have found is that these pumps seem to be very sensitive to voltage, more than the 255 pumps. On stock wiring they perform the same or worse than a 255. Once you upgrade the wiring then you see the difference. Maybe a lot of these people with lean issues are running the stock wiring.

 

When set to factory (43.5 psi) base pressure:

The Walbro 255 lph pump @ 30 psi boost draws about 10.5 A @ 13V.

The Walbro 450 lph pump @ 30 psi boost draws about 17.5 A @ 13V

The Walbro 450 draws 67% more current than the 255 under these conditions, and it is a well-known fact that the factory wiring cannot support a 255. Simply put, the terms "Walbro 450 pump" and "factory wiring" do not belong in the same sentence.

 

So highly recommended rewire for 450lph?

 

Installing this pump with the factory wiring makes as little sense as installing a large audio amp with factory radio power and ground wiring.

 

I have a 450 rewired with 12G into a 30amp relay and im still having fuel pressure problems. Base fuel pressure is stock and its correctly seated into the hat. Do you think my problem is the wiring still being to small or should I be looking for another issue?

 

12ga may be sufficient if the length is no more than a few feet, but not for long runs. Crutchfield's wire guage chart supports this. I wouldn't recommend anything less than 8ga, especially if the battery is still under the hood. My setup uses 4ga power and ground straight to the battery (in the trunk), and that's enough to keep 14.3V on twin 255s at full tilt. One really needs 20A capacity with some headroom to be sure.

 

I found this a bit surprising, so I had to check. The Crutchfield FAQ recommends 10 ga for 10-13 ft runs (From battery to pump is about 10.5-13 feet depending on route) running up to 35 amps.

http://www.crutchfield.com/Learn/lea...uge_chart.html



However, perhaps more interesting is the voltage drop estimate on this website:

http://www.bulkwire.com/wireresistance.asp

For this webpage, a 13 ft run of 10 gauge running 20 amps at 13.8 VDC will have a 0.26 V drop. 8 gauge is 0.17 V, 6 gauge is 0.1 V, and 4 gauge is 0.07 V. I'm actually at 10 gauge with my install, but must admit that I find 8 gauge a bit more preferable. 4 gauge is definitely the ultimate.

 

Im not sure what your issues are. I have my fuel pump hard wired with 12g wire, inline fuse, and a relay setup. I made about 630/470 on e85 at 32#. This was on a stock fuel rail/fpr and 2150cc fic injectors.

 

My battery is in the trunk and my wiring is very short. Maybe 2.5- 3 foot total with an inline fuse and a 30a relay. I have 2150's, single walbro 450 intank, fuel labs regulator, stock lines. Are you guys wiring 4-8g wire in the top of the hat?