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

[Gary - K7GLD]

I suspect the use and expense of hood scoops will prove overkill unless you have personal objections of use of the blower setups Bob and I use - besides, the scoops are only functional at road speeds, and really aren't likely to do much good at slow speeds or after the engine is shut down (heat soak), unless they were physically HUGE in size...



There are VAST open areas around and below these Cummins engines that actually permit lots of airflow - results of another test and thread I did verified tests others had done previously - actual, constantly monitored underhood temps at speeds above 30 MPH or so usually are within 10 degrees of ambient outside temps - not much to be gained by hood scoops while the vehicle is in motion!



I just this past week pretty well finalized my own blower installation, moving the large and ugly temporary scoop from below my air dam to in BACK of the air dam, drilled a pair of 3 inch holes in the air dam for air flow, and the final install came out quite well - far better than the monstrosity I have had hanging below my air dam - time and miles will tell if it's as effective



Here's a pic of what I made up, before it was painted - just a smaller size bread pan with a 3 inch diameter air duct molded into it at the proper location and angle that is then connected to my pre-existing ducting:



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[JAG1]

Hello Gary, I appreciate your info on the hood vent/ scoop. While reading that very intently, I realized, I will not be cutting any holes. Especially in a 36,000 mile truck.



I like your idea of the ram for the air. Thinking about this off and on for the whole day... . 'how am I going to get the propane torch, heat plastic, and mold it to fit to the bumper hole?'... ... . Funnel as I call it, and then adapt the 3 inch duct to that? A bread baking pan? I like that! Although I'm limited without an air dam, and having to use the bumper. My stubborness will get me to figure out something. I'll let you know what I come up with.



I did go get alot of things I'll need for the blower today. Have to do it in stages. Just Gotta' get over the hesitation of starting from the bumper. Tiredness from a hard week is starting to fade away. Oo.



Thank you both, Mike

 

[RSarvie]

Holy long threads Batman!

Interesting reading nonetheless. The reason I stumbled across this was I'm looking for ways to do the OPPOSITE of what this thread involves, or maybe I don't have to after reading here??? I'll explain...



Here in Minnesota, we are not only using ULSD now, but also, at minimum, a 2% bio blend by state law. With that there are new reports this year of gelling and what not surfacing that have never been reported before, due to bio gelling/cold filter plugging at higher temps than previous non-bio fuels.



I have a FASS 150 installed and have by-passed the stock filter housing that also contains the fuel heater. So... short story long, I wanted a way to ensure my fuel stays fluid and doesn't clog my filter, (currently 6 micron, next will be 3 micron) in the extreme temps we sometimes experience here, as well as out west. (Snowmobiling) I have never had a problem with filter plugging..... yet, and have run Power Service religiously in operating temps to -36F, and overnight sitting temps to the -20'sF. That was with non-bio fuels however. I'm trying to be proactive here, possibly thinking of maybe hooking up the coolant lines to the FASS now, although that seems like a lot of plumbing work.



After reading this thread, and hearing all the testing, does anybody have any return fuel temps in COLD weather conditions, colder the better? I'm wondering with the return fuel coming out of the VP/injectors going back to the tank, would it be a futile and worthless effort to look into adding a heater to RAISE the fuel temp to ensure proper cold weather operations, or is my return fuel already going to be adequate enough to eventually warm the fuel in the tank? So in essence, if I can get the truck started, which hasn't been a problem, the current fuel system itself will warm it sufficiently enough to de-gell the remaining?



I am thinking someone in this thread has some cold operations data that I might have missed? I read up to page 13, then jumped to the end. Otherwise I will have to run tests myself. Any recommendations on a temp unit I can drop down the filler neck into the tank for my tests if needed? Or will an IR temp gun be good enough to read fuel temps inside the tank read externally on the tank?



Thanks to all for your insight and testing results. It will hopefully prove I have little to nothing to do to ensure continuous operations in the cold climates with the recent fuel changes.

 

[Gary - K7GLD]

Here's sorta the final shots of my intake duct blower setup - if anything about these projects really is "final"... :-laf



First is the pic of the twin 3 inch ports - I plan to make or buy appropriate trim rings to dress the openings up.



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And here's a view from the backside of the airdam, showing the neatly direct path of ducting to the bilge blower:



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A more detailed pic of the bread pan adapter - it simply snaps and stays in place - I applied a small dab of silicone compound at each lower corner for extra safety:



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[JAG1]

I installed my blower in a very neat install (wish I had pics) coming off the funnel like bumper hole. Ran the wires, but don't have the switch in yet. I would like to find a timer as well as having a switch for manual overide. It's going along great, my hose comes up to the vp more in an upward angle aiming the the same place as you guys.



One big concern I have is wether I have made a mistake using only a 3 inch 145 cfm blower. I did this because of the small area behind the bumper. An eventual temp guage would be in order. Did you Gary or Bob, just use a wireless remote digital thermometer glued to the vp? need to get something.



Thanks a bunch... . an on going project, Mike

 

[rweis]

I used a wired remote digital thermometer.



The remote sensor is on top of the EBC (Electronic Bay Cover) where the electronics are mounted. However I think you could mount the sensor anywhere on the fender side fo the VP44 because the VP44 is aluminum housing and should have a prettyeven temperature gradient. I would not mount it on the engine side incase you would pickup a disproportient engine block heat reading.



I picked the wired one I found because the sensor was about the size of a kernal of corn, very small. Wireless should work if you can get something that wil mount to the body of the VP44. It would be very very interesting if your wireless sensor had 2 or 3 sensors and you could place them on different parts of the Vp44 and you could switch between them to see if the temperature gradient of the VP44 really was a even distribution. That would be very very interesting information.



If I were doing the same thing I would put one by the EBC, one by the outflow valve or right on the outflow line itself, and one on the fender side toward the top but not as high as the EBC but in that same front to back location. I think the heaviest work in the VP44 is done where the rotor is and the plungers are and they are about 2/3rds back from the front face of the VP44 (I think, based on the book on the VP44 I have).



That would yield significantly interesting information.



Gary has the timer information figuered out. It is an electronics experimenter timer kit. DIY kit 141 specifically multimode timer kit CK1416. You can buy it as parts and assemble it yourself or as a factory assembled circuit board. If you have trouble finding it I had a spare factory assembled one when the blowe went out on mine I thought it could be the circuit board so I bought a spare. Gary figuered out how to keep it powered even with the ignition circuit off. Very very very ingeneious. We use the circuit board relay to trigger a power relay so the blower amperage does not go through the circuit board relay eventhough the circuit board relay can handle 10 amps itself. Gary can explain it best, but I have the emails he sent me as to how to do the jumpers etc to get the blower power to stay on when the ignition circuit is not powered.



Bob Weis

 

[Gary - K7GLD]

I currently use 2 temp monitoring setups. I have one installed to the PSG body to directly monitor it's operating temp, the other is attached to the head of the fuel return banjo bolt.



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Temp readings seen so far with my setup involving all types of operation including RV towing in steep terrain show the 3 inch blower and duct to be entirely adequate - at least the way mine is installed. The PC CPU heatsink I installed and pictured earlier in this thread made a very significant difference in removing heat from the upper area of the VP-44.

 

[rweis]

Gary,



What kind of temps do you see on the fuel return banjo bolt during high rpm (2k+) operation preferably towing. I wonder if it is reasonably like the actual fuel temps. The old BK thread implied that at high rpms the fuel flow THROUGH the VP44 was about 30 gph. Just wondering what you see.



Bob Weis

 

[Gary - K7GLD]

Gary,



What kind of temps do you see on the fuel return banjo bolt during high rpm (2k+) operation preferably towing. I wonder if it is reasonably like the actual fuel temps. The old BK thread implied that at high rpms the fuel flow THROUGH the VP44 was about 30 gph. Just wondering what you see.



Bob Weis

Temp differentials between input/return of the VP-44 run from about 5 degrees around town to 30 degrees or slightly more under the heaviest loads such as towing the 5er up a grade in the RPM range you indicate. There is a definite and rapid rise in return fuel temps as the engine demand increases.



That differential is even more dramatic without the outside air cooling in operation - and of course, both input and return temps are both way upscale as well. In other words, the effect of the added cooler air both lowers overall temp differentials as well as lowers the VP-44 temp itself. At least that's the way it works out for me.

 

[rweis]

From the Bosch book the work done (heat generated) by the VP44 is DIRECTLY related to the rpm's.



The Vp44 does not know if you are towing or not, only the rpm requested.



The advance timing position etc is only delivery timing angle to the Vp44. It rotates and generates the same fuel fuel flow at the same rpm regardless of what the timing or the APPS is doing, thus the higher the rpm, the higher the work done, the higher the heat generated.



Could you hang some rough numbers on the non blower input and output fuel temps? I know it probably has been some time since you ran without a blower, just some general observations is fine.



Even with all the return fuel coolers doing their thing, cooling the VP44 to the maximum extent possible (when you need cooling) turns the Vp44 into the ultimate fuel cooler.



I am finding cooling the return fuel (I changed the H7B from a input fuel cooler to a return fuel cooler about 2 weeks ago) has a greater effect than cooling the input fuel. The tank level has a major effect on the fuel temp as the amount of fuel decreases toward minimum. The less tank level, the hotter the fuel (as you would suspect, less volume). The less the tank level the greater the temperature differential between the heated fuel and the OAT and the better the return coolers work. The greater the differential between the cooled VP44 and the fuel the more the VP44 acts as a fuel cooler. Quite unexpected from the outset that the VP44 would end up being a fuel cooler.



With the blower I can keep the VP44 temp rise arrested (the more ram air to the Vp44 the better), the input fuel still rises a little (a couple of degrees) and then stabilizes a couple of degrees above the VP44 body temperature.



From your input to the return fuel temps, if the OAT is 100*, my VP44 temp is about 105* - 107* my input fuel temp is about 112* and at cruise (2k rpm) the return fuel is 142* (ie +30*) then through the fuel coolers with a differential of OAT (100*) to 142* and the coolers knock off about all of the 30* VP44 work related increase in fuel temperature, to return 112* back to the slightly cooler VP44 (105*) where a couple of more degrees of temp in the fuel gets knocked off before the Vp44 work effort heats it back up again.



Of course all the above assumes you WANT to get heat OUT of the fuel.



In the winter you could just turn the blower off all together (as you have mentioned in previous post in this thread). Let the fuel heat up and let the OAT absorbe the excess fuel heat. You may not even need an alternate return fuel routing not through the fuel coolers. Of course you could change return fuel plumbing in the winter to bypass the return fuel coolers if you wanted even more heat in the fuel.



The last couple of days it has been cool (40's) here in central florida (I know that is a far cry from what some of you are experiencing in temperatures). I have noticed the fuel pressure is about 1 psi greater when the temperatures have been cooler (I use PF in every tank). This afternoon the temps were back in the 70's and the fuel psi was back down that 1 psi. How does the fuel psi change with temperature where it is really cold? The VP44 is still looking for 13. 5 psi (calibrating psi) input regardles of cold or hot.



I'm thinking that fan run time after shutdown is determined by where you live. The hotter the longer after engine shutdown run time. My goal is no more than 105*. Right now when it is mild OAT temp the hottest after engine shutdown is about 90* with 1 hour blower run time.



With the Bosch fix of the brass advance piston I bet we have a handle on this (assuming input psi at cruise is very close to 13. 5 calibration psi, volume is adequate, clean, lubricated, etc etc etc).



Bob Weis

 

[Gary - K7GLD]

Weather here is too cold for reliable testing - typical VP-44 temps are running below the fuel heater threshold, so will have to wait until it gets warmer.



There's no doubt that the higher engine RPM is the key issue in heating the return fuel from the VP-44 - but I'm pretty sure there is an even higher level as load is increased as well - perhaps related to fuel solenoid open/close time? And for that matter, we haven't really touched on what add-on power devices and programmers such as my Comp and Smarty might contribute as well.



I'll keep testing and monitoring temps...

 

[rweis]

I got a second thermometer today and will mount it under the hood around the VP44 body so I can get the vicinity temperature, and then I will put the remote sensor on the fuel return line. I have my fuel return line wrapped in a thermal blanket so it does not pick up engine block heat. I'll just zip tie the sensor right on the line and see what that yields.



I have to open the hood each time to get readings, but it has min, current, max readings for both zones.



I will move the thermometer body to different places around the VP44 to see if the ambient temp at various locations around the Vp44 body are the same or nearly same temps. The remote sensor I will leave zip tied to the fuel return line as I move the thermometer body around. Maybe even put the thermometer body between the VP44 outside of the thermal blanket and the block to see how hot the side of the block really gets. All we really know is the water temperature inside fo the block at this point.



Should be interesting. Should be able to coorborate your earlier findings. Might be one of the best $10 I have spent in a long time.



Bob Weis

 

[JAG1]

Thanks for the offer Bob on the extra timer you have. I just don't know what I'll do right now with that. Looks like you and Gary have fairly complex circuitry involved with switching and timers. Are they automatic? I was thinking just a more simplified version of a timer, like a mechanical one that runs off the battery, you turn a knob for whatever duration.



That is very ingenius the way you guys are using relays not running the blower thru the switching circuit. Never ever thought of that.



Took a 2 hr run today without the blower on (65mph). Just let the funnel capture outside air pushing it up to the vp. I have never seen this ever before where my mileage continues to increase. At first I just isolated the ff off the intake manifold, and began to see an increase. Next I installed the blower/ducting for outside air to the vp. Now my average keeps going up, has increased by 1. 5 mpg. Hand calculated miles after fill up came to 23. 89 mpg empty, combined city and highway. Does that seem right to you? If it is..... this cooling the fuel is a very good invextment not just for the vp. I must repeat... ... . I have never seen my average fuel economy keep increasing like this before.



Hats off to both you and Gary, Mike

 

[rweis]

The timer was Gary's idea. It is all automatic. It is a hobby timer "slightly modified". Gary was the one that figuered it out. Works really well.



I try to never have "power" going through what ever switch circuit I am doing. The relay socket and harness, and relays are redially available at NAPA. Same concept as the headlight harness from Summit Racing. The RAM headlight switch only caries relay power instead of full headlight power that overheated it. You do wind up carrying a spare relay though in the "tool box".



On the fuel mileage. We found the same thing. Not sure why. Denser fuel?, I do not know, just a nice side benefit. I think mine was about 1 mpg all said and done. After ~75k miles I get 16. 64 average, all hand calculated. I do pull a heavy 5er on occassion though. Those 5er pulls take the mpg on that tank to 12. 67. Although the VP44 does have a fuel temperature sensor in it to adjust fuel delivery with, not sure how it works though.



Probably this friday I will do the second temperature module. I have one in the cab now that is cab and VP44 EBC. #2 will be under hood temp and VP44 return fuel. Should be interesting.



Right now with 1 hour after shutdown blower running I am getting in the low 90's max temp on the VP44 EBC. OAT is low 80's. I think not enough run time on the blower. I think the driver is how long the block retains heat more than 100*. It is a big heavy engine block with lots of mass.



Welcome to "Experimentation 101", nice to have another guy helping out with data collecting and "experimenting".



Bob Weis

 

[rweis]

Well I could not wait to see what the VP44 return fuel line temperatures were going to be so I put the remote sensor on this morning before I came to work.



Only one drive (take all of this with a grain (pound) of salt)

Fuel tank 2/3 full (ie fuel mass)



OAT 55*

Fuel input 58*. VP44 EBC 58*. Return fuel line 58* before engine start.



Engine start 1 minute at idle 58*, 58*, 58*

After 10 minutes @ 1900 rpm 60 mph 60* 58* 71* delta 11*

After 10 more minutes @ 1900 rpm 60 mph 63* 56* 77* delta 14*

After 10 more minutes @ 1900 rpm 60 mph 66* 57* 81* delta 15*



After 1 minute acceleration to @ 2400 rpm 75 mph 67* 57* 88* delta 21*

After 5 more minutes @ 2400 rpm 75 mph 67* 57* 89* delta 22*



After 1 minute Slow down to 1900 rpm 60 mph 66* 57* 81* delta 15*

After 15 more minutes @ 1900 rpm 60 mph 67* 57* 81* delta 14*



Early conclusions:

VP44 rpm = VP44 work done = temperature added to input fuel minus what is happening with the body of the VP44 temperature wise.



It only took about 10 minutes for the VP44 return fuel temperature addition to stabilize. The return fuel temperature stabilized before the VP44 case temperature stabilized.



Generally at 1900 rpm the VP44 was adding about 15* once the VP44 body temperature stabilized. At 2400 rpm the VP44 added about 20*. When the rpms were reduced the work done in the VP44 reduced and the temperature addition dropped immediately back to 1900 rpm +15*.



The amount of fuel temperature the VP44 adds to the return fuel is directly related to the rpm of the VP44 and any other temperature related impacts to the VP44 like external case cooling. This makes a case for case cooling during engine run time (I think) I will shut off the OAT blower and then see what the temperatures do.



We might have a target as to how much heat we need to get out of the fuel to keep the fuel within the VP44's input fuel temperature limit of 160*.



1 drive does not a test make, but I thought I would share some of the preliminary information and observations.



Bob Weis

 

[Gary - K7GLD]

Bob, your numbers at cruise look quite similar to mine - be interesting to see what effect towing the 5er will have - although terrain differences between Florida and out west makes a big difference in engine load...

 

[rweis]

My theory is RPM is the only thing that drives VP44 heat (except for its environment ie under hood temps, ram air, insulations, OEM ff heat protected ie where more heat can enter the system that the VP44 did not generate).



Engine load, except for higher engine environment heat, should not make a difference because just more fuel goes to the injectors rather than down the fuel return line. Same number of piston cycles, same number of rotor revolutions.



If my theory is correct, then the manufacturing tolerances and amount of internal lubrication are THE driving factors to keep the VP44 induced heat to a minimum. The tolerances have to be tight so it will pressurize to the 1000's of psi required. And therefore why the failure rate is so high if anything gets in the fuel like water, particulates, lack of lubrication. There is just zero (or pretty close to zero) tolerance in the fit of the rotating parts.



Which supports even more the OAT blower concept to provide an external heat removal method and not let the internal very tight tolerances become even tighter and tighter as the intrnal components heat up and expand their size and decrease the already tight tolerances even more.



I think this is going to underscore how important it is to cool the fuel and the VP body. Maybe the PSG cooling is going to be secondary and cooling the mechanical mechanism primary.



If you get the mechanical mechanism reasonably cool, the PSG WILL BE COOL because of the effort done on the mechanical mechanism.



I assume since that you got similar temp readings that 2000 rpm was +15*, 2400 rpm was +20*.



I am going to run 1600 rpm on the way home and see if I get +10* ie is rpm LINEAR to temperature added? or is it curved?



Bob Weis

 

[Gary - K7GLD]

AS I see it, the VP-44 will ALWAYS pump the same volume of fuel per revolution, regardless of load - the difference is in the percentage of that fuel that is actually used to feed the injector lines at high PSI, or simply returned to the the tank at lower PSI - and correspondingly less load on the pump plungers.



For instance, if the engine is spinning at a constant 1600 RPM with no load on it, relatively little fuel is actually being fed to the injector lines, most is simply returned thru the pump at low PSI and on back to the tank.



BUT, now increase the load on the engine to the max it will handle without lugging - and what happens THEN to the applied demand on the VP-44 plungers? It would seem logical that the increased workload would ALSO require each plunger to spend a far greater percentage of it's cycle under greater pumping load than it did with no load at all - with a corresponding increase in generated heat as the plungers, rollers and cam ring all see greater stress loads.



SURE, the VP-44 pumps the same VOLUME of fuel at each RPM, and WILL generate additional heat as RPM increases due to friction effects even with low/minimal load - but I seriously suspect that the higher overall operating pressures required as load and fuel demand increases will also add more generated heat in direct relation to fuel pumped to the injectors, and work done...



We'll hafta both do more testing to verify actual temp changes, same RPM, light load vs full load...



I'm pretty sure a heavily loaded VP-44 at 1600 RPM will generate more heat than a lightly loaded one at the same RPM, even tho' total fuel volume pumped is the same.

 

[rweis]

Well, I am going to take the position of:

I do not think that weight load will vary the VP44 work load and therfore temperature.



I will also re-read the Bosch book to see if it sheds any light on the subject.



I think that the VP44 does the same work at a given rpm regardless of what the injectors are doing.



This will be an interesting topic. It is interesting when two differing views work on the same problem and have no idea of the outcome.



Definitely will be a learning curve.



I can understand your point of it takes more APPS at the same rpm to carry a load than it takes unloaded and therefore therefore generates more heat at the higher load .



I know the engine drive train works harder because of heat buildup in it. We will have to be careful that we are not picking up the additional heat from the engine drivetrain which the blower should take care of.



My thought is there is a certain amount of fuel either burned or not burned at a certain rpm. If there is a greater load then more of it gets burned. Whatever the excess fuel is after the distributor plungers have resealed gets shuttled back to diaphram cavity to help replinish the incomming fuel resivour or to the tank if the resivour is full. If the distributor plunger is held open longer (more APPS) more fuel goes to the cylinder. But none the less whatever is not distributed to the cylinder goes back diaphram cavity or to the tank, BUT the rotary pump does not have any different stress on it and therefore the temps will be the same.



Bob Weis

 

[JAG1]

Do you see any problems with me changing my fuel return line to go into the fuel fill neck? I want to use the foam/overflow tube alongside the neck by cutting it off up on the high end nearer the cap, leaving enough nipple to clamp on a return line there. I'll have to increase from 3/8ths to 5/8ths and it will have to run uphill some to get there. This will help to mix additives poured down the filler neck while running, and remove the hot fuel return from being picked up right away by the draw straw so close in the tank module. Are there any problems that you see?



Next I don't want to have problems with the rollover valve sticking, not letting the tank vent creating a vacuum and a harder working lift pump. So my next step would be to place a screened vent (marine type) just inside the fuel door. This would connect the overflow/foam tube, that was origonally connected to the filler neck, to an outside vent. Do you see any problems as a result of doing this? Thank you much... . this is easey stuff to accomplish, and just one more step in the process of cooler fuel and cooler VP.



Btw, I have a timer on order, rated for 10 amps, I don't think I'll need a relay, as the fuse will blow first... . 5 amp.