Engine/Transmission (1998.5 - 2002) VP44 - the light dawns - maybe...

[Big White Beast]

Here's the skinny........

I believe the filter rating was 10 microns at 45 GPH. So far it has held up longer than others I tried and no loss of pressure.



Here's the part #s all available fron Napa.



Fuel Filter #4006 $7



Filter Mount #4309 $27



Pusher Pump #P4070 $90 (Napa packaged Carter 4070 pump)



Don't forget to tell them you have AAA or some other way of getting a discount.



Because of the size of the filter mount and where I originally mounted the pusher I didn't have much room for fittings. I wanted to put some valves on to accomodate changing the filter but there was no way without moving the pusher way up. I do have some vice grips with the flat ends that gently squeeze the hoses shut and that seems to work OK. It's working for now so I wont mess with it.



Garrett

 

[Diesel Freak]

This is a Post I made a while back on NW Bombers!

I got bored at work again and decided to start a thread on fuel delivery to the VP44.



Looking at the Engine Data Plate on my ETH I calculated the fuel flow out of the VP44 at rated speed of 2700 RPM and 245 HP.



Fuel flow out of the VP44 is 107mm^3/stroke.



At rated speed this comes out to 13. 74 GPH. Assuming 30 GPH recirculation (a number I remember Kondolay posting a while back... John, I am sure you can ask him to make sure) we come to a total of 43. 74 GPH.



This means that to maintain zero PSI at the VP44 it must be fed with an unrestricted 43. 74 GPM of fuel. This is without fueling boxes.



Then I thought... what would happen if we installed a fueling box that raised the VP44 duty cycle by 82% all the way to 3200 RPM.



I came up with a whopping 29. 64 GPM that was delivered to the injectors. Adding in the 30GPM recirculation gave me 59. 64 GPH.



So to maintain zero psi one would need almost 60 GPM to feed the VP44 with a Box that fueled to 3200 RPM with an 82% overfuel.



But who wants zero PSI? Not me!



I would rather have 15 PSI at the VP44.



Multiplying our flow rate by two to ensure we have plenty of fuel gives us 120GPH.



Who has a reliable 120GPH fuel pump that is regulated at 15 PSI?

 

[Gary - K7GLD]

The obvious REAL question to the above, is, would the additional fuel required actually be taken in at the VP44 INLET - or merely be diverted INTERNALLY from the "normal" bypass flow? After all, IF the incoming fuel flow rate IS determined purely by rotationl speed of the VP44 mechanical built-in lift pump, the fact that the fuel consumption rises due to a fueling box will NOT/CAN not, in any way "force" the built-in LP to spin any faster - or deliver any more fuel - and the only OTHER source for it to come from, is in the excess that would NORMALLY be INTERNALLY bypassed and returned to the tank...

 

[GLASMITHS]

Gary

That is reasonable. It is also reasonable to conclude that since the out-put of the VP-44 is controlled by the speed of it, not the inlet or lift pump pressure, then a fueling box that uses gross amounts of fuel over stock, would use up that which would normally be returned to the tank as cooling. Sounds like a Rx for failure?

 

[Gary - K7GLD]

"Sounds like a Rx for failure?"



EXACTLY my point!



Put a heavy load on the VP44, bleeding off the cooling flow it needs, at precisely the time it needs it most - say up a long steep grade pulling a heavy load - perhaps 5-10 minutes at a time...



Some of us have been assuming we could FORCE extra fuel thru the VP44 in those cases by use of higher pressures and larger lines - and in cases where stock flow and pressures could NOT keep up with demand, we HAVE made obvious improvement - but I suspect there IS a limit to what can be reasonable expected from the VP44 in terms of flow - and that those who make large demands for SHORT periods of time are probably relatively OK - but guys who run Comps on 5x5 and use big injectors - and divert fuel needed internally for cooling and lubricating the VP44 on much longer power demands might be seriously shortening it's lifespan...



It looks to me, based on apparent Bosch specs, that any maximum fuel demands that draw more than about 15 GPH - leaving 30 GPH for spec'd cooling, might present a problem if done repeatedly...



That's why I asked the question - "how much power can we get out of the 24 valve engine on 15 GPH of fuel?"

 

[cgoder]

vp 44

Great post guys. Keep it coming!

 

[MCummings]

A couple thoughts.





Okay.



It looks like the limiting factor of how much HP a 24V truck can make is the Low Pressure pump in the VP 44.

Looks like we need to get rid of this low pressure pump and run High pressure High flow pumps straight into the VP44.



So to me,,, it looks like,, even if we upped the fueling rate to 95%+ we would only starve the fuel solenoid and High pressure plunger, because the low pressure pump is restricting fuel flow.



We have enough Lift Pump Solutions out there,, We have the fuel flow and fuel pressure.

Who is going to be the first to get a drill/hacksaw and/or other non-surgical tools ahold of the VP44 to remove this Low Pressure Pump.



I wonder if DD has tried something like this?? Sounds like HP to me.



Looks like we need a new type of fuel gauge also... a fuel rate and fuel pressure.



0-100 GPH and 0-50 PSI



My $. 02



Merrick Cummings Jr



P. S. Anybody want to mess with my Spare VP-44,, Just don't break it,, it's my slightly used spare. Wouldn't mind doing a before and after dyno test with the Low Pressure pump removed...



EDIT: Getting rid of the Low pressure pump might not pick up HP, but would definatly help overfueled trucks like mine keep the VP-44 cool during Heavy fueling.

 

[Diesel Freak]

Originally posted by MCummings



EDIT: Getting rid of the Low pressure pump might not pick up HP, but would definatly help overfueled trucks like mine keep the VP-44 cool during Heavy fueling.

dont forget that the low pressure pump provides hydraulic pressure to the timing solenoid... . if you got rid of the low pressure pump... . you would have little control if any of the timing ring and piston

 

[MCummings]

Then maybe just the "pump vanes" ?



Merrick Cummings Jr

 

[Big White Beast]

Your all over my head on most of this........

But, one thing to remember is that the stock filter is only rated at 45 GPH also. I would assume that's optimum with a clean filter.



In a different thread where they were talking about too high of pressures there was a good discussion on pressure versus flow. Any positive pressure would mean your supplying the VP more than it can use.



So for my own clarification. If your pressure never drops to or below zero I would assume your feeding enough fuel for the VP to feed the injectors, but not necessarily enough to keep the cooling functions up?



Not knowing enough about the VP internally. I would have to ask how it decides to split the fuel. Does it primarily feed the injectors and what's left it uses for cooling or does it always divert an amount for cooling? At what percentage do you jeapordize the VP? Say 70% for consumption and 30% for cooling. If it will divert all the fuel to the injectors getting rid of the low pressure pump wouldn't net any horsepower as it already gave it all it had.



And the last silly question before I give up for the night. Does anyone actually tow on 5X5, let alone with larger injectors? It seems EGT's would be more of a problem than a lack of cooling fuel.



Garrett

 

[Gary - K7GLD]

Garrett - *I* tow on 5x5 all the time! My truck is totally stock other than the K&N, drilled airbox and the Comp - EGT's never go above 1200 - my clutch still lives, and power figures are in my sig... I have what I consider a VERY well balance power level, in which all I need do is DRIVE - no eyes glued to the guages, etc...



MERRICK - I'd be VERY curious, since you say you have a spare VP44 (lucky guy!), are you able to force air thru it in it's obviously stopped condition? is there any way to apply a guaged pressure - up to perhaps 16 psi or so to determine if the internal bypass valve will open to flow even with the internal LP stalled? I'm curious about leakage past the internal LP - or any other possible fuel flow routes thru or around the internal LP we might be missing here...



As far as over-running the VP44 with use of fueling boxes - perhaps I'm worrying about nothing - at least as far as "normal" power mad users are concerned - Mopar Muscle was using a box and injectors on his flow tests - and still was getting the spec 30 GPH thru the VP44 - tho inlet pressure was at zero - so at least for stock setups, that might be the ragged edge of practical power enhancement without over-running the stock lift pump, lines and VP44...



After that, yer probably on slippery ground...

 

[GLASMITHS]

VP-44 Cooling

After re-reading Mopar Muscle's post, I don't believe that the high HP boxes will take from the cooling fuel. From his post it maintains the 30gph no matter what. So it makes me haft to agree with BillK, that all the drilled banjo bolts, braided lines, oversize pushers, adnausem, does some good for yo Ko-Jones, but nothing for the VP-44

 

[Scrappy]

vp44?

Correct me if I am wrong, but if we put injectors in it that are so big that they don't allow anything for cooling then wouldn't the injector flow also cool the pump?

 

[Gary - K7GLD]

The injector pump cylinders are a FIXED displacement - as is the volume of the VP44 internal LP at specific RPM's - the changes in actuaI fuel output from the VP44 come from solenoid valving action that allows changing flow volume depending on demand - but I doubt there is any way you could "divert" bypass flow entirely to the injectors... And I seriously doubt there is any scenario where the injector pump section of the VP44 can be forced to over-run the volume the LP pump section is designed to provide, I suspect the required percentage of bypass flow is pretty well designed into the pump, and pretty hard to significantly alter - even with fueling boxes...



As far as coolent flow, injector vs bypass, I would assume different flow paths are used for each only to a small degree - and then, exactly WHAT is it we are wanting cooled/lubricated by either the bypass or the injector flow? I would assume the moving parts of the pump are what requires the most cooling and lubrication from fuel flow - and that part of the flow probably IS the same for both bypass and injector flow - I don't know for sure... (way too much guesswork here... )