Question for racers running MFI...

docdan200 · 08-07-2012, 03:20 PM

I'm hoping that those similarly situated, and have found a viable solution, can share their inputs...

Given that the OEM Bosch fuel pump for the MFI is close to unobtainium, I was wondering what our vintage racing friends and tracksters have done in the form of alternative options to this fuel pump dilemna.

Can you go with an aftermarket electric pump, given that it's rated at 15 psi, and have no fueling issues during track conditions?
How critical is it with the MFI that the circuitous fuel "return path" be followed?

I have read and heard of others who have abandoned the OEM Bosch MFI fuel pump and OEM MFI fuel filter console, and opted for aftermarket fuel pumps, which are plentiful, readily available, and relatively inexpensive, and simple, "1-in, 1-out" fuel filters, and have run their cars with good reliability.

I'm just looking for a more reliable, easy-to-acquire, solution to this issue.

RSTarga · 08-07-2012, 03:52 PM

I think the race cars used a different pump exactly like the one on a 6.3 mercedes

304065 · 08-07-2012, 03:56 PM

ATL Fuel Cell
Walbro In-tank Pump
Fuel Pressure regulator mounted on cell fill plate with peanut Bar gauge

skidmark · 08-07-2012, 05:08 PM

I have used 911 cis or motronic fuel pumps. Plenty of pressure and flow. I would stick with the return flow. It could help keep the pump and the fuel cooler. Also a good idea to not circulate engine oil through the pump. Runs the pump temps way up. Put a breather on the pump and fill it with oil. Henry at Supertech sold me the parts to do my car.
Mark Kinninger

304065 · 08-07-2012, 05:43 PM

The trouble with eliminating the oil supply to the pump is twofold: first, the pump body doesn't heat up, so you are relying solely on the thermostat for warm-up mixture control, and second, you have to remove the pump to change the oil, which is a huge project.

callard · 08-07-2012, 05:56 PM

On my SCCA race car, I got my pump from Summit Racing. 15 PSI and about 1.5 times the flow. Plumbed back to the stock filter assy, MFI pump and return line with AeroQuip dash six. Wideband Data Acq shows that it works great. The tricky part is the mods to the space cam.

docdan200 · 08-07-2012, 11:23 PM

This forum's just plain great!! Thanks for the input guys...👍

Callard:
Exactly the set-up that I had in mind. Did you use the stock MFI filter console? The one that has 4 outlets, 3 on top and 1 at the bottom?
I was thinking of using a "1-in, 1-out" type of fuel filter...like the ones for the CIS engines, but without the fuel accumulator.

In this set-up, the "return-line" back to the tank will see the return-line from the MFI intake stacks and return-line from the MFI pump meeting at a T-junction.

Could this possibly work?

And like yours, this is for an "S/T tribute" car that I plan to use for vintage racing.

callard · 08-08-2012, 07:37 AM

Docdan,
Dunno about your T junction. I use the stock MFI console with a button on the dash to activate the cold start valve on top of the console. Handy for warm ups.