Engine/Transmission (1998.5 - 2002) Modifying fuel system so temperature input to VP44, 80* - 100*, your inputs.

[rweis]

Texas Diesel -



I do not know of a way to measure internal temperature of the VP44 except by the temperature of the fuel going in vs the temperature of the fuel comming out with the difference being the heat rise generated by the VP44. Marco says the VP44 internal input fuel temperature is one of the temperature values available with the proper reading tool.



Sort of like measuring engine oil temperature, radiator fluid temperature, differential fluid temperature, transmission fluid temperature. All are not the temperature of the actual component, but the cooling fluid going through the component. The component could have a very different temperature, but we ASSUME (and you know what assumeing is) the component temperature is reasonably close to the cooling fluid temperature.



How would you measure internal VP44 body temperature?



I think you are saying that in Gary's case he is measuring the EBC cover temperature and you are saying the circuit board may or may not be close to the same temperature.



Probably true if you measure the fuel temperature as well. Fuel temperature would not necessarily equal the circuit board temperature. Although the fuel is routed under the circuit board bay and used to cool the circuit board bay (as well as the rest of the VP44).



On engine shutdown both Gary and I flood the upper Vp44 area with outside air for a couple of hours trying to draw heat away from it and provide a sort of heat barrier for it. Not scientifically correct for sure, but a sensor mounted to that area should reasonably show how the heat in that area is rising or falling and the effect that the air flow is having in the general direction of the temperature.



We (Gary and I) each have a slightly different approach.



I am trying to cool the cooling fluid that circulates throughout the VP44 to try to get to the internal temperatures in general and the electronics bay in particular. My theory is cooler fluid, cooler component, then do your best to hold or lower the total VP44 mass temperature after shutdown.



My bench mark is 100* maximum fuel input temperature. The benchmark is purely a WAG, and just a value that if I can hold the input fuel to that benchmark (100*) then the VP44 internal temperatures SHOULD be well below the limit (by Bosch) of 160* fuel input temperature. (My first misting (see above) install will be this weekend. )



What would your ideas be to help with the longevity of the VP44 with respect to temperature?



Bob Weis

 

[Gary - K7GLD]

Since a handful of members here permanently reside in my "Ignore" bin due to past unpleasant encounters, I'm not aware of the specific issue Bob covers and responds to above.



BUT, if the complaint/criticism is that merely circulating cooler air over the VP-44 is ineffective in cooling internal components - especially the relatively temperature sensitive computer board, then we'll just have to agree to disagree!



That board, like MOST solid-state devices, is seriously challenged by operating temperatures above 150 degrees or so. The VP-44 itself is both cooled and lubricated primarily by fuel flow thru it.



That's generally fine as the engine is running, and the vehicle is in motion - but in our trucks, recirculated fuel that has been heated in it's flow thru both the VP and the engine steadily heats the rest of the fuel in the tank - which in turn steadily increases the operating temperature of the VP-44 - THAT has been well proved by previous operating over-the-road temperature testing done by Bob, me, and other contributors in this thread.



Even if we attempt to add fuel coolers to the system to reverse the normal occurring temperature rise while the engine is running and in motion, we STILL must come to grips with other underhood heat sources at lower vehicle speeds and after engine shutdown - heat-soak!



The VP-44 sits in a relatively enclosed area, within an inch of an engine that operates at nearly 200 degrees - and also shares space and radiation from the exhaust system that may well be well over 400 degrees at engine shutdown, as well as the water and A/C radiators - not a very comfortable environment for components threatened by temps over 150 degrees or so!



Since we cannot continue to flow fuel thru the VP after the engine is shut down to continue cooling until other heat generating components have cooled, what CAN we do?



Well, we can do as much as possible to ISOLATE or partition the VP from nearby heat radiating sources - as I have done with my aluminum foil "partition" (ever see a BHAF heatshield?) - and we can also work at bringing in what is essentially the only remaining resource easily at our disposal - cooler outside air to bathe the VP-44 and control temperature rise from hotter nearby sources until their temperature has moderated.



IS cooling the VP-44 with cooler outside air effective - and is merely reading VP-44 case temperature a reliable indicator of internal temperatures?



Well, it's NOT likely to be as effective as circulating liquid THRU it - but since that's not an option, critics will have to ask themselves:



Which do you prefer for a temperature sensitive and expensive device that HATES and is damaged by exposure to temps above 150 degrees, to simply do NOTHING, and let it be constantly/frequently "baked" in a 200 degree oven - or perhaps do what you can to provide supplemental air cooling that at least externally maintains VP-44 outer case temps at about 100 degrees - under the logical reasoning that if the OUTER case is held at half of what it would otherwise be exposed to, there must certainly be significant reduction in INTERNAL temps as well?



It's pretty obvious that I, and Bob, will gladly take the substantially cooler measurable VP-44 case temperatures, by any reasonable methods at our disposal!



And ain't it strange/humorous that the SAME folks questioning the value of applying cooling to the OUTSIDE of things to manipulate the INTERNAL temp, are the SAME ones who will rush home from the store to put their beer in the refrigerator, and ice cream in the freezer - which only supply cold temperature to the OUTSIDE of the goodies? Why not just leave that stuff out in the garage if that approach is so worthless? :-laf



Now, if critics here in this thread want to continue to challenge and disallow this approach and line of reasoning as a beneficial effort to cool and protect the VP-44 on a purely theoretical basis - as opposed to extensive and lengthy actual hands-on work and testing of some of us here, then I guess they might find more interesting reading in some of the other threads offered by this board.



OR, perhaps go get a can of beer outta the fridge... :-laf

 

[SKneeland]

"Since we cannot continue to flow fuel thru the VP after the engine is shut down to continue cooling until other heat generating components have cooled, what CAN we do?"



i dont see any reason why the lift pump wiring couldnt be modified to allow the pump to continue to run after the engine is shut down, be it on a timer etc. that, coupled with a heat exchanger/cooler in the fuel system, may or may not make a difference, but seems easier than fabing up a forced air system

 

[Gary - K7GLD]

"Since we cannot continue to flow fuel thru the VP after the engine is shut down to continue cooling until other heat generating components have cooled, what CAN we do?"



i dont see any reason why the lift pump wiring couldnt be modified to allow the pump to continue to run after the engine is shut down, be it on a timer etc. that, coupled with a heat exchanger/cooler in the fuel system, may or may not make a difference, but seems easier than fabing up a forced air system

Lots of 24 valve owners concerned over significant VP-44 issues mistakenly think there is an available fuel pathway open thru the VP-44 even when it's not functioning - NOT TRUE!



The first internal obstruction inside the VP blocking flow, is the internal mechanical vane pump that has spring-loaded vanes, that in itself, as well as other internal blockages essentially seal off the fuel flow, and making it impossible to "force" fuel thru the pump when it's not running.



Some also see the Overflow valve outlet there right next to to the fuel inlet, and wrongly assume that fuel PSI over it's 14 PSI or so rating will be passed back to the tank even when the pump isn't operating, but there's LOTS of other passages and blockages between that outlet and inlet that stop flow, even though they are physically close together.

 

[rweis]

SKneeland -



I think the VP44 cooling issues are two fold.

1. During run time

2. After engine shutdown (ie heat soaking from the engine block temperature)



The during run time is a fuel fluid (used for cooling) temperature issue (unless I can lower the temp of the VP44 itself). The after engine shutdown is a VP44 environment issue (unless I can get the VP44 cool enough to not heat up much while the engine is cooling down) (like Gary wrote: there is not an open fluid passage through the VP44 when it is not rotating, wish there was though).



One question I hope to answer is (OqIhtai) if I can cool the VP44 down enough during run time that it does not need after run time cooling. That would eliminate the after engine shutdown outside air blowers. If I can get the VP44 during engine run time down to something like OAT - 20* and if it then heats up 30* after engine shutdown to OAT +10* then the after engine shutdown blower would not be needed.



OqIhtai can I keep the VP44 cool enough during run time with the outside air blower combined with run time misting that it does not need fuel cooling and the after engine shutdown time can be reduced from 128 minutes (2hr 8 min) to something a LOT less time (20 minutes?).



OqIhtai can I take fuel from the tank at OAT +10 and return it to the tank at OAT or something cooler without any fuel coolers (cooler than when it entered the VP44, plus the work (temperature) done by the VP44) then the VP44 would itself would be the fuel cooler (or heater in the cool weather time, misters on in the warm weather, off in the cool weather).



Lots of questions that all need testing.



Any and ALL ideas / questions / thoughts / fluid mix / etc welcome.



Bob Weis

 

[Texas Diesel]

info .

Texas Diesel -



I do not know of a way to measure internal temperature of the VP44 except by the temperature of the fuel going in vs the temperature of the fuel comming out with the difference being the heat rise generated by the VP44. Marco says the VP44 internal input fuel temperature is one of the temperature values available with the proper reading tool.



Sort of like measuring engine oil temperature, radiator fluid temperature, differential fluid temperature, transmission fluid temperature. All are not the temperature of the actual component, but the cooling fluid going through the component. The component could have a very different temperature, but we ASSUME (and you know what assumeing is) the component temperature is reasonably close to the cooling fluid temperature.



How would you measure internal VP44 body temperature?



As far as practical there is no way, short of imbedding a sensor inside.



I think you are saying that in Gary's case he is measuring the EBC cover temperature and you are saying the circuit board may or may not be close to the same temperature.



That IS my point. You cant cool the engine by blowing air on the valve cover.



Probably true if you measure the fuel temperature as well. Fuel temperature would not necessarily equal the circuit board temperature. Although the fuel is routed under the circuit board bay and used to cool the circuit board bay (as well as the rest of the VP44).



Fuel is a liquid and by nature can carry away more BTU's of heat than air. Running cooled fuel THROUGH the VP INTERNALLY would certainly have a good effect on the VP INTERNAL and should be a lower temp reading on the external case as a result.



On engine shutdown both Gary and I flood the upper Vp44 area with outside air for a couple of hours trying to draw heat away from it and provide a sort of heat barrier for it. Not scientifically correct for sure, but a sensor mounted to that area should reasonably show how the heat in that area is rising or falling and the effect that the air flow is having in the general direction of the temperature.



I understand what you are desiring to accomplish, I share the same desire. But I dont see how blowing air on a 2 sq inch heat sink mounted on the cover of the electronics bay can draw enough heat from the VP INTERNALS, considering how much latent is available from the thermal mass of the cast iron Cummins engine.



We (Gary and I) each have a slightly different approach.



I am trying to cool the cooling fluid that circulates throughout the VP44 to try to get to the internal temperatures in general and the electronics bay in particular. My theory is cooler fluid, cooler component, then do your best to hold or lower the total VP44 mass temperature after shutdown.



My bench mark is 100* maximum fuel input temperature. The benchmark is purely a WAG, and just a value that if I can hold the input fuel to that benchmark (100*) then the VP44 internal temperatures SHOULD be well below the limit (by Bosch) of 160* fuel input temperature. (My first misting (see above) install will be this weekend. )



That will work



What would your ideas be to help with the longevity of the VP44 with respect to temperature?



Thats easy, follow your path with cooling the supply fuel, there is no doubt in my mind that that you are on the right track here. As far as post shutdown heatsoak, considering the thermal mass on the engine, thats a tough one. If I ever replace my VP (still good at 150k miles with a history of TST power max, Edge, and now a VAaken) I want to see if I can install a gasket between the timing cover and the VP to reduce heat transfer. It's just an idea. Now that I have a 'good' LP my idle surge and bucking SEEMS to have ceased. Went through 3 LP's to get one with steady PSI.



I add 2 cycle oil at 200:1 to the fuel, I feel the low lubricity is ONE of the reasons the VP doesnt live too long sometimes. I'll let you know in 100k miles if mine original VP is still pumping.



If you recall I insulated the FF from the cylinder head and added a fuel cooler.





Bob Weis

Gary, you kill me :-laf

n .

 

[rweis]

Texas Diesel wrote:

... I dont see how blowing air on a 2 sq inch heat sink mounted on the cover of the electronics bay can draw enough heat from the VP INTERNALS,...



I agree, but I have the VP44 wrapped in a thermal blanket and flood OAT into the air space between the blanket and the VP which basically keeps the engine block heat from reaching the VP44 and inflicting heat soak to start with. The fact that I aim the air flow at the top of the VP where the EBC is might be only consequential but that is also where the EBC is. The time period of 128 minutes is because it takes that long for the block to naturally cool down to approximately OAT. Flood cool air until the threat has passed.



If you are trying to cool your arm you would blow air on your arm not your foot. The air does not actually penetrate the VP body, but it will keep air moving across the VP body and help carry surface heat away and therefore make that area a low point in the temperature signature of the rest of the VP body and cause heat to migrate to that area resulting in cooling the entire VP body. The VP seems to be made out of aluminum and the heat transfer through the body should be reasonably good.



I do like the idea of a gasket between the VP and the mounting system, like some did with the OEM ff.



If I can add mist to the cooling air stream on the VP it should increase the heat removal transfer ability of the air flood stream. Cooler fuel input should result in a cooler internal temperatures to start with and therefore less heat to deal with to keep the VP within a "cool" range.



Cool it internally, also cool it externally. It is just a giant interelated puzzle, no single piece is the silver bullet.



Bob Weis

 

[Texas Diesel]

Bob, I agree 100%, you have a comprehensive approach.



One thought, if you shut off the engine and come back 1 hr later, what is the relationship between VP temp and say, block temp? What I am getting at is to leave your fan on the VP running for say, 50 minutes. Turn the fan off, then the VP will equalize itself, internal temp and external temp. And then see if the VP has a lower 1 hr elapsed time temp then. Perhaps since I have no fan and no thermal blanket I can record and give some data to you. Then we might have some quantitive temp data to see how much the blanket and fan are reducing the heat soak temps of the VP?



If you are interested I will start comparing VP to block or timing case.



-----------------------------------------------------------------------



One other observation, after adding the PS cooler, I see 40F lower temps on the PS pump. The biggest (and surprising) difference is how much less radiant heat there is in the area around the VP. All the heat from the PS (200F) was being radiated out.



Just an observation for you.

 

[Gary - K7GLD]

I have the VP44 wrapped in a thermal blanket and flood OAT into the air space between the blanket and the VP which basically keeps the engine block heat from reaching the VP44 and inflicting heat soak to start with. The fact that I aim the air flow at the top of the VP where the EBC is might be only consequential but that is also where the EBC is.

Photos - and WAG's can be pretty deceiving - and the assumption that my setup in particular is only intended, or in practice, ONLY cools the VP top cover is dead wrong!



Fact is, I have the airflow adjusted for about 60% over the top area and down the backside of the VP, and 40% down along the front.



The goal was to provide a slightly greater percentage flow to the temp sensitive VP CPU area, with the continued flow on over and around the lower space between the VP and the block to apply more cooling airflow heat barrier and isolation between the hot block and the VP.



The rest of the flow effectively cools the front side of the VP. The temp pickup probe on this installation is attached to the VP main body directly between and slightly above the fuel input/output ports.



My 140 CFM setup is hardly intended to only "cool the heatsink... "

 

[The Adjuster]

Gary & Bob



Not to hijack the thread ... but have been following this one for some time and have a quick question, I have the juice / attitude on my 01 and was wondering where it reads the fuel temp from? The ECM must read it from somewhere?



I did a 600 mile trip the other day coming from Mobile, Al back to Weatherford, Tx and thought I would play with the juice while cruising.



Abient temp was 80 according to overhead display, cruising at 75MPH for 1 hour fuel temp was 112, IAT was at 108, water temp 185.

Got onto I49 (no police in these parts) and cruised at 90MPH for around 45 mins fuel temp was 128, IAT 112 and water 190.

Back down to 75 for another hour and fuel temp 113, IAT 113 and water 188.



Fuel tank level was kept at 3/4 as I transfered from aux every 30 mins or so.



Juice was on 3. 3 the whole time (wire is tapped) and I do not have the stock filter and fuel is fed from tank through 10 micron filter then to two holly blues (in parallel not series ... 14PSI idle, 12 PSI cruise) then through another 2 micron filter and straight to the VP.



Just some more figures for your files (not that you need any more).



Kevin

 

[rweis]

The Adjuster - FIRST, THANKS FOR THE DATA, THE MORE DATA WE HAVE THE BETTER WE CAN UNDERSTAND WHAT IS HAPPENING.



You are seeing exactely the relationship between rpm and fuel temperature.



Abient temp was 80 , cruising at 75MPH for 1 hour fuel temp was 112 - In your setup your fuel temp is approx 32* above ambient after 1 hour @ 75 mph and whatever engine rpm that gives you.



EDIT: I checked mine at 75 this am and I run the expected OAT + 10 + 6. The +6 is my baseline at 1400 rpm is +10 and 75 mph gave 2k rpm which is 600 rpm over the baseline and I see 1* / 100 engine rpm. OAT was 65*, EBC was 80*. If I extrapolate that to your 80* OAT, my 75 mph (2k rpm) would give an EBC of 95* vs your 112*. I think that is saying I am getting 20* out of the fuel with the fuel coolers I have right now. With the water mist I hope to get an additional 20* out. Testing will tell. Those temps are EBC which means the 5* difference between the fuel temp and the EBC are already taken into account.



cruised at 90MPH for around 45 mins fuel temp was 128 - for 15 mph the temp difference was 16* additional about 1* / mph additional



75 for another hour and fuel temp 113 - approximately what it was before



However the OAT fuel temp relationship does not seem to hold in the reverse direction. My tank is hardly ever LESS than OAT +10. If I could get the tank to OAT I would be fairly ok with that. However it seems to heat up to OAT + 10* regardless of what I do.



I would be real courious to see what your fuel temp is at as slow a speed as you can turn your VP ( ENGINE) and not get run over for an hour. I would bet it is OAT + 10*.



OH, what was your rpm at 75 and 90? I would bet you get 1* fuel temp rise per 100 rpm of engine speed (50 rpm of VP rpm speed).



There seems to be a direct relationship between VP rpm and fuel temp, which makes sense as that is where the work is being done in the VP. Now remember the VP is heating up the ENTIRE tank volume. In the old "pump, lines, whatnot" thread BK determined at higher speed (pump rpm) the VP cooling stream was 30 gph returned to the tank, or just about the entire tank volume per hour.



At OAT 80* your fuel was +32* above OAT. Now lets change the OAT to 100* and drive 90 mph. OAT 100* assume at 75 mph (rpm) +32* = 132*, now accelerate to 90 mph and add another 16* = 148*.



Now I find the EBC is about 5* hotter than the fuel, 148* + 5* = 153* (We can not measure the actual computer board temp so this is best guess)



Your PCM is about 153*. Now what temperature is your soldering iron tip? Not much difference than your PCM temperature. Of course the PCM is engine mounted (VP bolted to the engine block) and being vibrated on the Cummins "6 cylinder vibration machine". Is desoldering the PCM board connections a problem?



Every time the fuel solenoid opens to recharge the rotary high pressure pump, the solenoid gets 18 amps to start the action, then 10 amps to hold the action. The VP turns at 1/2 the engine speed. Apply an all but constant 10 amps to the solenoid ( and for fueling boxes add more closed time so more fuel reaches the injectors) and cool the computer chip that is doing 100's of millions of calculations / second with 153* fuel (remember the Bosch limit is 160*). WIthout ANY failures in calculations while you are adjusting things like timing as well. I think you have a receipe for virtual guaranteed eventual failure.



THEN



We have this say 140* VP PCM and we shut the engine down and let it heat soak for an hour while we go have lunch. What then? The block is 180* - 190* within 1/2" of the VP. The VP is made out of aluminum. Wonder where the VP temp is now? (ie why Gary and I force OAT on the VP for 128 minutes after shutdown). We can keep the block temp off the VP by not letting the hotter environment get to the VP through the OAT air flood we do.



EDIT I checked the VP OAT blower temps from last night. EBC at shutdown was 95*, OAT was 86*, MAXIMUM EBC temp was 99* (within 4* of when it was shutdown, never hotter), of course the engine water temp was about 180*, BUT the VP was not subjected to the block temperature because of the OAT air flood and thermal blanket protection.



Now



We can keep the heat soak off the VP with the OAT air flood. Just need to get the VP running temps down.



IF we can get 30* - 40* out of the VP with cooler fuel or cooler environment around the VP I think that would be good, and hence the experimentation.



Bob Weis

 

[GWedekind]

In case this helps... here is a picture of the VP44 with the module removed.

 

[rweis]

Did anyone else NOT get GWedekind's picture of the VP44 with the module removed?



Bob Weis



ANY info or pics or whatever of anything even remotely related will help

 

[R-N-R]

I do not see it either.

 

[GWedekind]

Sorry. . will try again

 

[GWedekind]

here is another pic

 

[rweis]

What is the larger cavity to the right in the pictures do?



It looks like maybe a fuel cavity with a common side to the electronics bay to help keep the electronics bay cool?



Is the VP44 made out of an aluminum alloy? ie heat transfer ability.



Bob Weis



Great pics BTW



I have a worth looking at post #29 (today 5/17) over in the https://www.turbodieselregister.com/forums/showthread.php?t=158145 thread. I had a phone call the Southeast Power Systems Tampa about an upcomming club meeting and got into talking about the VP44. I think it is worth reading (at least this one post, maybe not the entire thread)

 

[Gary - K7GLD]

HMMmmm - do the above pics indicate a DIRECT contact between the incoming fuel supply and the PSG? If so, and that cavity IS held full of fuel in normal operation, it leads to perhaps attaching more focus upon cooling the incoming fuel as more important a direct benefit than thought earlier - by me at least...



I had figured most PSG cooling was obtained primarily by conduction to it's mounting surface, THEN by fuel flow to THAT surface - not directly to the PSG itself.

 

[GWedekind]

Yes, the larger cavity is where incoming fuel is staged and flows against the bottom of the PSG module. It flows from the cavity through the little hole by the overflow port and then up into the PSG module. Look at the one pic that has part of the PSG in it and you will see the little nub that fits into the "fuel port" on the LH side of the pic. It is clearly evident that fuel does flow into the PSG.



Also, Bob asked if the VP was aluminum... yes it is.

 

[rweis]

I really hate to disect words but I would really like to know exactely.



Yes, the larger cavity is where incoming fuel is staged and flows against the bottom of the PSG module. It flows from the cavity



through the little hole by the overflow port and then up into the PSG module





Look at the one pic that has part of the PSG in it and you will see the little nub that fits into the "fuel port" on the LH side of the pic.



It is clearly evident that fuel does flow into the PSG.



Please bear with me.



FUEL flows INTO the large cavity, then INTO the PSG cavity? Meaning fuel flows DIRECTLY onto the PSG module? Like the PSG is immersed in flowing fuel?



IF that is what you are saying it puts a whole new meaning on "cool fuel"



Bob Weis