mikjel

E85. When does the fuel pump have to be upgraded?

blown 944

My experience is it is good for around 350 maybe a liitle more true rwhp. Depending on your parts will determine whether it will be enough. Pressure is not the determining factor airflow is. Some make 400plus hp on 15psi.

Baptizo

???

spammajamma

It’s all ball bearings nowadays. Now you prepare that Fetzer valve with some 3-in-1 oil and some gauze pads. And I’m gonna need ’bout ten quarts of anti-freeze, preferably Prestone. No, no make that Quaker State.

95ONE

^^^^ OK.. FLETCH.. ^^^^^ small Chevy Chase reference.

Bri Bro

Do the math.
Horsepower * BSFC = Fuel (lb/hr)

B.S.F.C for:
Normal Aspirated Engines is .45 - .5
Supercharged Engines is .55 - .60
Turbo charged Engines is .6 - .65

For 420 HP Crank (350 wheels)
420 * 0.6 = 252 lb/hr

convert to gallons per hour since most pumps are specified that way.
1 gallon gas = 6.3 lbs

(252 lb/hr) / (6.3 lbs/gallon) = 40 gallons/hour


So to get 350 RW HP you need to pump at 40 gallons/hour at the correct pressure (3bar in my case). With E85, you are past the capacity of a stock pump since you need +20% more fuel.

m73m95

Are we sure he isn't asking if e85 requires a different fuel pump, from corrosion issues? (Been asked a thousand times before, I know)

Adonay

In my car the pump couldn't deliver for more than 20 psi boost on E85. So if you plan to run E85 to safely bump up the boost pressure you wont get far with out a better pump.

mikjel

Ok. Thank you for the answers!

alxdgr8

Make sure to upgrade the wiring if you upgrade the pump

Scott H

Eh, I've never seen the point of this. You will never be flowing enough (at least with a walbro) to see more than just a few amps. Yes it can pull 20 amps, but that is way, way more fuel than the car uses.

Adonay

There are people that claim the wires get hot with for example the bosh 044 pump i have. I just did the wire mod with a relay connected to the old wires.

alxdgr8

http://realstreetperformance.com/sto...on-test-5.html


I've read quite a few people on this forum talk about hot wiring from an 044. Simple security measure. You don't want to have a large voltage drop to you fuel pump causing a lean situation.

Scott H

Huh, well I'll add that to the list of things to do. I forgot to take into effect the boost pressure that will increase fuel pressure (duh) so yeah, I can see how you could easily start pushing more amps than those tiny wires can handle. Especially on a track when you're constantly on the boost.

Bri Bro

I installed a Walbro GSL392 and measure the voltage at the pump with the car running. The voltage at the pump was a little over 12.5 V with the alternator running at 14V at idle. I ran a 12 gauge sister wire along side the original factory wire and tied it into the fuse box on one end and the pump at the other. I also ran a new 12 guage ground wire to the pump. The voltage drop decreased to 0.5 volts and the pump is now seeing 13.5 volts.

The pump running at 3 bar (44 psi) is pulling 8 amps. That is too much current for the factory wire going to the pump, the wire will not melt but you will see a voltage drop that will effect the performance of the pump. Increasing the voltage at the pump also increases the GPH rating so it is a good thing to do.