Fuel Pump for EFI FE

[Dimis]

Hi gents,

What sort of fuel pump pressure do I need if I'm planing to run an EFI on an FE?
So, I guess the real question is: What fuel pump do I need to supply that pressure?

I think I remember reading something by Rick Lake on this topic but I can't seem to find it...

Thanks in advance

[blykins]

I would use a Walbro or Aeromotive. Depending on what setup you have, you could run anywhere from 20-40 psi.

[RICK LAKE]

Dimis Have to remember I was going with super charger and 10 psi of boost. With just the motor and 55 pound injectors, idle WITHOUT the vacuum con trolled regulator on is 44-46 psi. With the regulator running it drops into 36-38 psi. This is at 750 rpms. Sorry I don't have the cycle % off the top of my head. I started with a 452 motor and now run a 482 stroker. The setup was about the same. The amount of fuel dumped is alot and I run FI motors soft on A/F ratios with racing. At WOT my duty cycle is only 68% with 46 psi on the rails. I have 2 Walbro 255 litre pumps in the tank with 2 supply lines and anti reverse flow valves. 1/2" supply to a V block and goes to a #12 line to the rails. Return is #8 back to the tank. This is way over kill. One pump of 255 in the tank with a #10 line supply and #6 back to tank will do a fine job. i am not a fan of deadhead fuel rails. Over time small partials get to the injector on the end of the lines and you start to have problems with injector flow and spray patterns. Trade off is than after 20 minutes of track time my fuel is warm. Again 2 pumps working. Find somone WHO really knows how to setup an FI system and you will be fine. I leave about 15 pounds of tork and 22-25 HP with running a soft A/F ratio and timing. Motor will last for years. Clean the plugs is cheap after racing. Sand bead and regap. They are lite black which could also be a little oil from the PCV valve or flooded valve train. Both sides are the same color. Good luck Rick.

[Barry_R]

Pretty common pressure values are between 40 and 50 pounds. The common aftermarket EFI systems are usually looking for around 45 although OEM stuff can be much higher these days. Like Rick I use a return system.

Best pumps for long term durability are OEM style Bosch, Carter or Walbro stuff. Race pumps like the Aeromotive or Weldon are higher output but seem to be shorter lived. Lots of guys prefer to run a pair of the OEM Bosch pumps for the proverbial best of both worlds.

Most common injector sizing formulas are referenced to published flow rates, which are in turn based on +/-80% duty cycle. Smaller injectors will generally have better controllability at low flow - nicer idle and part throttle behavior.

[428 Cobra Jet]

Guy's,

Just did a F/I changeover using the weber manifold and webers (tried to keep the look) but upgrade the fuel system, anyway to get back to your question, I used the Mallory fuel filter and 140gph pump that was already installed to the vehicle, I made a 250ml surge tank with a second inline filter attached directly to a 044 Bosch OEM fuel pump (flows to 700hp) to a fuel pressure regulator set at 35lbs. It's a 427 s/o with 428 crank, rods, crower stage 5 hyd cam, shaft mounted roller rockers, ported heads, in 70 fastback, 4 speed, 3.89 rear end and it puts out 394.6hp at rear wheels. Good Luck,

But I am going back to a 2x4 setup, the injection seemed to tame the engine too much, it lost its mongrel feeling that all good Big Blocks have.

Darryl

[Avmaviator]

I had order an aeromotive one but it was too long for the stock mounting location of the Kirkham. So I ordered a Mallory "stand up" one which is good for 100 psi, but we only need 45 psi for the system. Hopefully that one will work out better mounting wise. If it becomes a problem for durability and such in the future then I will switch to a Bosch or something like that, and tackle the mounting issue. At this point I went the "easy" route because I want to get the car on the road. Hopefully the "easy" route will last me long enough.

[PANAVIA]

Fuel pressure and volume are key concerns here -- Bosch makes a good pump that Tom Kirkham turned me on to , that you need a couple of metric fittings to use then you are online.

You need to have a conversation with the mfr of the system and have engine info ready.

the higher the pressure, the smaller injector you can use to a certain point.

old 86-93 fords used 39PSI , the new GM stuff runs at 58-60 PSI -- there are variables all over the place.

Steve

[Dimis]

Many thanks gents,
As a rank royal rookie in this area, I had to read it thrice to ensure I understood what I thought I was understanding, eventually me thinks I gets it.

But just in case... can you pls confirm what I've concluded.


Here's the low down -
I'm specking my car out with a return fuel line for EFI.
But the standard pump with the car is only good for a carbie, 5psi?.

I don't have the engine yet and wont have for some time, and will probably need to make a decision on this sooner rather than later.

Engine Parameters - FE - mild build, cammed mostly for street.
Cubes may be anywhere from 427 up to 482 stroker. Thus anywhere b/w 500-600hp & tq.

So from what I understand - Wolbor or Bosch that can get me at or just over 50psi is the way to go?
Or
I should just plumb the return line and then wait till the Engine details are confirmed and then go from there?

Your thoughts?


Thanks again

[blykins]

I would go ahead and put a return line in the car. It's nice to have one, even with a low-pressure fuel pump, as it keeps the pump from being dead-headed. I'd then nail down the engine specs, then purchase another pump when you decide on what fuel system you'll need.

[Avmaviator]

**Brent beat me at responding first, hah**

You can plumb the return line, and main fuel line (just leaving an area for a pump if you are going with an external pump) and just wait till you have your set up to finish the "ends" of the line.

You'll need a fuel pump, pre filter, post filter (optional but recommended), a fuel regulator for the range of psi you will need. The system you go with will dictate what exact fuel pressure you will need, and the kind of injectors. But like several folks on here have mentioned, it will be in the range of 45psi +/- a few. You will also need to regulator to control the psi at the rails/injectors.
The way mine is set up, using the FAST EZ-EFI system goes like this: Tank, line, pre filter, Mallory pump, line, post filter, fuel rails (the TWM system has two rails so I have to put a Y before the rails to split the line in two), through the rails, regulator, return line back to the tank. Like I mentioned before, our regulator is set at 46 psi right now (what was set on the dyno) and I will try to get it closer to 45 as per FAST.

Hope this clears things up? Or did I confuse you more?

Arno

[Dimis]

Ahhh... you guys are great!
I only had to read that once

I'm going with plan "A" hold off on changing the fuel pump till I've sorted the specs on the engine.

Thx

[RICK LAKE]

Dimis Problems are starting to show with gas here in the states. The 10-15% methonal is eating any rubber lines that are not designed to handle this kind of fuel. Over time the rubber is falling apart into small partials that are getting through 20 micro filters. Either plastic or Stainless lines are going to be the only way to go down the road.
Build your fuel system so you can expand without alot of changing the lines. Run your carb setup but leave it simple to just add a short line with added filter and one way valve and cap the line. Also run the relay and wiring for the electric pump. This way all you have to do is connect. You can always go back to a carb if needed.
In tank fuel pumps need gas to help cool them and extend their lifes, I run 1/4 tank min with 2 sets of baffles in the tank. I did have to remove the foam because it was breaking down. Tank foam was only 5 years old. May have been due to gas additives and boosters. Now run only 91 without and additives, even at track. Have added 2 gallons of 100 unleaded couple of times and found no change.
Walbro fuel pump(255) will push 80 psi if needed. Running #10 and #6 lines will give you an 700-900HP range. This should cover all your needs. As for injector duty cycles, going small will cause the driver to hold the injector open longer, make more heat to both, and over time burn out the system. You can make the injector run at a higher pressure but will cause failure of the pintle seat and cause a leak from fuel wash wearing out the seat.
A set of 45-60 pound injectors will be in the ball park for your setups. Dropping fuel pressure also drops flow to motor and makes a larger injector smaller, same applies the other way. This setup is for 8 injectors, 1 for each cylinder. A throttle body system would need 96 pounds for running a 452 or 482 and would ned to watch the A/F ratios in the 5,500 rpms and up for a lean out condition. You are looking for a 12.5-12.7 on accell and 13.2-13.5 on cruise for safe ratios. Can go leaner if needed, depends on weather around you. Good luck. Rick L.

[PANAVIA]

Good advise all - if you can manage , hard lines with well crafted transitions are the way to go - a #6AN should be good, - an 8AN feed with a #6AN return should be very close to spec. --