^^ I'm with you Greg.

I figured if it was good enough to last nearly twenty years without trouble, why not just replace the hose ... https://rennlist.com/forums/928-foru...with-pics.html ... and when it finally dies I'll just put in a new one ... and it will likely outlive me.

 

So this is getting a little bit more complicated; lots of happy people who have ditched the in-tank pump and found joy and others (928 knowledge based specialists) still on the fence. Makes it difficult for a learner like myself to get it right and not end up stranded on the side of the road.

Greg, I thought that you were okay with it (based on this comment)


The kit we are looking for to properly use the 044 pump should include the following:

1. New tank fitting with o-ring
2. Stainless strainer
3. M18 to 5/8" barb for the pump with a bonded seal
4. 5/8" fuel hose
5. Hose clamps
6. Strain relief for the hose - bending a hose this size at the angle needed was another challenge.

This is the stainless steel strainer that is shorter than the Porsche unit but has a larger diameter opening to allow more fuel to flow to the external 044 pump



I am still unable to find who to order it from
Can someone provide that info please as I am sure the testing period is over.
AO was one of the orig testers but never disclosed the Seller's contact info
Can we have it now?

Please and thanks

 

Its available from Tim Murphy - the supercharger expert and a rennlist site sponsor.

 

Thanks Hilton.
I have written to Tim


Absolutely. Waiting for Tim to respond if he's got stock

 

Fred,
Another link...
http://www.murf928.com/
or you can call Hacker.

 

Iny own car, I'd use an in tank pump to feed the 044 pump.

I have supplied pieces for the 044 pumps both with and without feed pumps, depending on the customer's desires.

I make a kit for adapting these pumps to the stock in tank pump or to a stock strainer.

Porsche used the 044 pump, in the factory Cup Cars without a "feed" pump, so you should be fine with that, even though people report them getting noisy when hot.

You will need to control it with a relay, as the current required to run these pumps stresses the stock wiring.

I make a relay kit for this application, too.

 

It is not a question of flow-- as Greg correctly points out, the stock strainer flows plenty of fuel. The issue is pressure drop between the tank (at atmospheric pressure) and the pump inlet-- something less than atmospheric pressure, depending on flow and plumbing size.

The problem with lower pressure at the pump inlet is that gasoline has a tendency to turn to vapor, at temperatures and pressures that are not far away from normal conditions.

Temperature, pressure, and vaporization are all interrelated. And pressure drop, flow, and tubing size are also interrelated. Porsche put the internal pump there for a reason: To overcome the pressure drop due to flow, and maintain a higher pressure at the pump inlet. This reduces the tendency for the fuel to turn to vapor at higher temperatures. It won't literally vapor lock (as in stall the engine), but it will reduce flow. How will you know unless you monitor fuel pressure at WOT, or watch AFR with a WBO2?

I've got a theory for noisy pumps: The lowest pressure is right at the rollers, which are sucking fuel from the inlet. If the fuel is going to vaporize it will be right there, at the moving parts, and then the vapor turns to liquid as soon as the pump raises the pressure. Could parts spinning in partial vapor be the source of the noise? If so, it would be worse with low fuel levels (less pressure), which is something that is often reported.

Ditching the in-tank reduces pressure at the main pump inlet, that much is certain. And depending on altitude and temperature that may or may not create a problem- likely not, but it is difficult to know how close to the "edge" you are.

But IF you want to ditch the in-tank pump, why not hedge your bet (which is what it is) by fitting a larger strainer?

Personally I chose to stick with the in-tank pump-- it is a good solution for a potential problem, and we do periodically drive in high temps, and at high altitudes.

 

The specifications from Bosch for the 044 pump calls for a larger feed line than the stock tank fitting can supply, which is why the larger unit was designed and produced.

I still remember when Todd called me: "Do you guys realize you are starving the 044 pumps? The minimum specification is a 5/8" feed line...."

He had already made an adapter for his car, I asked him to make one for me as a prototype and to make up a drawing for reproduction. We took this to Tim Murphy to start making the tank and pump fittings.

We actually talked about going one size larger but the tight radius of that bend proved to be a challenge, so we stayed with 5/8". Our goal was to keep the hose as long as possible for safety reasons. Too many hard fittings increases the chances of a breakage in the event of a rear end collision.

Not to pick on Rob, but this is the exact type of setup we were trying to avoid:
https://rennlist.com/forums/928-foru...ml#post8522881

Todd was very adamant about this. He saw multiple 928's (including Murphy's) with a setup like Rob's above. He felt this was a safety issue with all those hard fittings in such a short area between the tank and the pump.

So the Murf928 strainer served two purposes:

1. Properly feed the 044 pump in cars opting not to use the in-tank pump
2. Offer a better and safer method to connect the tank to the pump

Fred - you should be hearing from Murphy shortly, I was on the phone with him last night discussing the plans to do another production run of these. He does have a couple left he will be contacting you about.

 

Thanks H.
I need two, one for me and one for Livio

 

Sorry,
I am late to this discussion and have not read all the posts. In my industry (HVAC) special attention has to be given in selecting a pump with low inlet pressure. You have to make sure that the inlet pressure the pump sees is more than its NPSH (Net Positive Suction Head). If the inlet pressure is lower than the NPSH of the pump, the pump will cavitate and sound like it has marbles rattling around in the pump casing. The phenomenon of cavitation has been documented a lot in the industry and is caused by the pressure at the inlet being reduced sufficiently to make the liquid boil and the bubbles thus created hit the impeller causing the sound. The bubbles will also hit the impeller with such force that the impeller will see pitting and the pump performance will degrade as it is not pumping a liquid but a liquid/gas mixture.
Hope that helps.

 

In my opinion, most all of the analogies expressed in this thread are correct.

With the stock strainer it will starve the inlet to the 044 pump and I think Jim Coreman's explanation describes best what is going on.

With a full tank of gas you have enough head pressure at the 044 pump through the stock strainer where is it not a problem, it's when you get below 1/2 or 1/3 of a tank. You can audibly here the pump begin to whine as the fuel gets lower and lower in the tank.

I can't remember the exact setup that Todd had but with the high fuel flow he was using through the modified fitting to run parallel 044 pumps, he collapsed the stock strainer. Not sure exactly how he has it now but I know he modified the strainer and he only brings the second pump online at a certain rpm and boost level. Otherwise running two pumps at the same time just heats up the fuel when just idling or at cruise.

I like the idea of the in tank pump feeding the 044 pump and I think the strainer on the in tank pump, being a different design, would be up to the task. This will help with the pressure drop through the fitting but the problem with the in tank pump setup is they have an even smaller fitting/hose feeding the second pump. So, I’m not positive if that would be adequate or not keeping a positive inlet pressure on the 044 pump. You can pump a lot more fluid through a hole at pressure than you can pulling it though with vacuum. Did you ever look at the tiny tiny hole in the outlet check valve of the pump? Amazing you can get enough fuel through there to feed 650HP. I datalogged the fuel pressure with and without the check valve and there was a neglagible difference in fuel rail pressure between the two setups.

The new tank strainer I developed turned out to be a very nice, high quality robust design. For those who have had one in their hand I’m sure would agree. Problem is, they are expensive to make. I really was not planning to make anymore but if there is enough interest I guess I could look into a smaller run, but making the tank fitting was very quantity sensitive so I’ll have to think about it some more. Perhaps if I had at least 10 of them spoken for I could make a batch of 25 or so. The machine shop gave me the 50 piece price for 25 units the last time, not sure if he will go it again.

 

Thank you Tim. So I will start the ball rolling. Count me in for 1

 

That original line set-up on Rob's car was what I came up with, because I couldn't find a fitting that did exactly what I needed. The "metric" to "AN hose" fitment, at the outlet from the tank turned out to be very poor and we had leakage issues. Rob's car was the only vehicle that received these "trial parts".

I've now found a fitting that adapts the 044 pump directly to the stock hose that runs from either the strainer or the filter. Much better fitment, because it directly attaches to the stock hose.

 

Makes total sense to me.

I tend to use new pieces...because my labor rates sometimes make fixing/cleaning economical pieces impractical. Therefore, if I'm installing a new pump (including a new 044 pump), I'm using either a new stock strainer or a new internal fuel pump.

I'm guessing that a large percentage of 928 owners would spend hours figuring out how to get all those tiny little holes in the stock strainer cleaned out.

Obviously, the stock strainers become restricted with debris over time. Perhaps because I'm using new strainers I have not noticed any issue with restriction.

Tough to calculate strainer area from a picture, but I'd guess that your strainer probably has a larger area, making it a good choice, if replacing the strainer.

Because of the larger outlet, do you have a hose which connects this strainer to the stock fuel pump? That would make your part applicable in a much larger cross section of applications....since very few people want/actually need an 044 pump.

 

Sorry Greg, I didn't mean to imply it was a bad setup. I'm fully aware of the limitations of finding M18 fittings for the 044 pump. A lot of us has similar setups since as you stated, the necessary fitting didn't exist.

Tim scoured the earth trying to find the needed M18 to 5/8" barb since anything pre-made would have been significantly cheaper than making our own.