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jbrown's Avatar
 
Join Date: Mar 2006
Location: highland mills NY
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044 fuel pump

Running just alittle lean up top and I wanted to see if I could get alittle more fuel. I already have my fuel head done by Imagine auto and have BR adjustable warm up regulator. I have the enrichment section maxed out and still alittle lean 12.6-12.8.
I was doing alittle reading and I though I saw some guys using a 044 pump up front and one in the back and that helped with getting some fuel. Is that true. I have a 044 in the rear now and a stock at the front. I also read that it is not good to put two in series because the first one will put to much pressure on the back one and burn them out.
Anyone running two 044 and what are the results.
Thanks John
Old 01-25-2010, 02:45 PM
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Quote:
Originally Posted by jbrown View Post
I also read that it is not good to put two in series because the first one will put to much pressure on the back one and burn them out.
That's just not true IMHO. The factory did it - even on some of the N/A cars - and Bosch advise it if necessary.

All CIS pumps are fine running in series. The flow rate drops as the regulated pressure goes up - but the first pump makes it easier for the second pump, because the inlet pressure is already higher, and the flow isn't just gravity.

A bad pump will cause problems because it can restrict flow through it, and thus the inlet to the other pump.

Quote:
Anyone running two 044 and what are the results.
Thanks John
I'm not. A single 044 supports 400 FWHP for me. In fact, the probably-original, single 'S' pump in a 250,000 mile tub gave perfectly good AFR's with a stock-ish RoW 930.

Merv was running a pair of 044's IIRC, but his car was far from stock.

I think pumps will only help if you have a problem with your pumps, like they cannot sustain the required flow. Measure your flow rate.

A pair of 044's would sustain good flow rates at a higher system pressure than the stock setup - but if you don't need that, it won't do you much good.
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'77 S with '78 930 power and a few other things.
Old 01-27-2010, 12:11 AM
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How extreme is your build, boost, HP?

Is the HF FD a non lambda cast iron head?

Have you tested your on boost Control Pressure? If it is not down around 2 bar or so you are not going to get all the fuel you have.

Are you using the BL enrichment delay? If so, are you sure it is working correctly?

It might be good to check your System Pressure to.

Also check that both fuel pumps are working.

Just some thoughts.
Old 01-27-2010, 08:55 AM
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Why not run 2 - 044 pumps in parallel instead of series?
Seems that would deliver more fuel volume than 2 in series.
The 044 pumps are quite under rated and most of them put out alot more fuel and at higher pressure than the specification.

I remember 962-104 had 4 - 044 pumps in parallel. They were mounted in an aluminum frame that looked kind of like 2 - 4 cylinder engine fuel injector rails with 4 pumps mounted in between them.

The car didn't need 4 fuel pumps to run, they were there in case 1 or 2 of them failed during a race the car would not be affected and could still win the race and it did.
Old 01-27-2010, 09:14 AM
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Did the 4 pumps come from a catch tank fed by two pumps?

Some times multiple pumps are run to get fuel from each side of the fuel cell so there is less chance of starvation. One to each corner of the cell would be interesting.

Was the 962 CIS, MFI, or EFI?

I would think, pumps in parallel for quantity at moderate pressure (EFI).

Pumps in series for pressure which is what Porsche did with the 930's CIS.

Would the order of the pumps make any difference.

I was wondering if someone added a higher spec pump it might best be the last pump in series. Especially if they have built in pressure regulators. The one with the highest regulation spec might be best to have last.

Just spit balling again.
Old 01-27-2010, 10:33 AM
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Quote:
Originally Posted by 911st View Post
Did the 4 pumps come from a catch tank fed by two pumps?

Some times multiple pumps are run to get fuel from each side of the fuel cell so there is less chance of starvation. One to each corner of the cell would be interesting.

Was the 962 CIS, MFI, or EFI?

I would think, pumps in parallel for quantity at moderate pressure (EFI).

Pumps in series for pressure which is what Porsche did with the 930's CIS.

Would the order of the pumps make any difference.

I was wondering if someone added a higher spec pump it might best be the last pump in series. Especially if they have built in pressure regulators. The one with the highest regulation spec might be best to have last.
962 had an early version of race Motronic EFI.
The race motronic ECU box was red in color and most teams had 2 of them mounted on the bulkhead to the left of the driver seat so the driver could unplug the harness from one and plug the other in if it failed during a 24 hour endurance race. This motronic ECU had a fuel mixture trim knob on it so the driver could adjust the fuel mixture while driving.
They could richen it up for more power if they had plenty of fuel or lean it out and shortshift to get better milage if running low on fuel in a race.

I was doing mostly fiberglass and bodywork on the car back in the mid eightees so I don't know all the details and I don't remember if there were more fuel pumps then the 4 I mentioned. Alot of what I learned was during lunch conversations with the rest of the guys on the team.

Also, every teams crew chief set the car up a little different and they were always trying new things for more speed and reliablility so like alot of other systems on the car there is no concrete answer to the fuel pump set up, they could all be a little different after time and team modifications.
The fuel cell was filled with chunks of yelow colored gasoline friendly large-open cell foam rubber that kept the fuel from sloshing around during cornering and braking. I don't know if there were seperate fuel pickups on the bottom of the cell or if there was another fuel pump inside the tank.
The fuel cell has 2 fill openings at the top, one on each side of the car. Only one was used during a race while the other was closed off.
The direction the cars were pointed in through the pits in relation to the pit wall and the teams fuel rig decided which one was used.

The 935 had a seperate surge fuel tank between the main fuel tank and the injection pump each with it's own dual or triple fuel pump array running.
I remember the 935 used the same fuel pumps that the Mercedes 6.3 liter engine used from the 280 SEL 6.3
Both of the 935 and Mercedes 6.3 used mechanical fuel injection.
Old 01-27-2010, 11:13 AM
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