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Engine/Transmission (1998.5 - 2002) Modifying fuel system so temperature input to VP44, 80* - 100*, your inputs.
- Thread starter rweis
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If I install a cooler in the bypass, Do you think it would be
some what effective????
NO.
The heat is generated in the VP44. You need to get the highest heat run through coolers to get the biggest temp drop. You need to run the VP44 return fuel through the coolers.
The bypass fuel is the same temp as the tank temp because all you have done is pumped it from the tank to the bypass and now it is going back to the tank without picking up any heat from the VP44.
I also found cooling the fuel before the VP44 was not as effective as cooling the fuel after the VP44 because the VP44 is where the heat is generated.
I even tried misting the vp44 with water mist trying to get the heat out of it. The VP44 is just a big block of aluminum after all. Did not work. I think I needed way more water than I could carry (100 gallons?). I thought of puting the VP44 IN A WATER BATH. Could not perfect the idea.
I did find that the OAT blower turns the VP44 into a fuel cooler above about 45 mph. The ram air flushes heat off the vp44 faster than the VP44 can generate heat. Prior to 45 mph the input fuel temp was lower than the VP44 case temp. After 45 mph the input fuel temp was higher than the VP44 case temp. Cruising at 60 mph for hours the whole tank fuel temp would drop to the OAT meaning the fuel temp extraction was greater than the fuel temp addition by the VP44 due to pumping psi and rotational friction and solenoid action (which is one of the greatest temp additions I think).
The OAT blower then also floods the VP44 (and for me because I drilled holes in the APPS pocket and vent some of the blower air out the APPS pocket top to cool the APPS) after engine shutdown to keep the block heat off the VP44 so it does not heat up after shutdown from latent block heat. The block is nothing more than a large stored heat source until 1 (Gary's timer) - 1 1/2 (my timer) hours after shutdown. Remember the solder on the PSG starts to melt at 140*, the block is 180* by definition of the water temp. The VP44 is aluminum and absorbs heat really well from the block. The blower floods the VP44 with OAT to keep the block heat from migrating to the VP44 frame and the PSG.
Bob Weis
some what effective????
NO.
The heat is generated in the VP44. You need to get the highest heat run through coolers to get the biggest temp drop. You need to run the VP44 return fuel through the coolers.
The bypass fuel is the same temp as the tank temp because all you have done is pumped it from the tank to the bypass and now it is going back to the tank without picking up any heat from the VP44.
I also found cooling the fuel before the VP44 was not as effective as cooling the fuel after the VP44 because the VP44 is where the heat is generated.
I even tried misting the vp44 with water mist trying to get the heat out of it. The VP44 is just a big block of aluminum after all. Did not work. I think I needed way more water than I could carry (100 gallons?). I thought of puting the VP44 IN A WATER BATH. Could not perfect the idea.
I did find that the OAT blower turns the VP44 into a fuel cooler above about 45 mph. The ram air flushes heat off the vp44 faster than the VP44 can generate heat. Prior to 45 mph the input fuel temp was lower than the VP44 case temp. After 45 mph the input fuel temp was higher than the VP44 case temp. Cruising at 60 mph for hours the whole tank fuel temp would drop to the OAT meaning the fuel temp extraction was greater than the fuel temp addition by the VP44 due to pumping psi and rotational friction and solenoid action (which is one of the greatest temp additions I think).
The OAT blower then also floods the VP44 (and for me because I drilled holes in the APPS pocket and vent some of the blower air out the APPS pocket top to cool the APPS) after engine shutdown to keep the block heat off the VP44 so it does not heat up after shutdown from latent block heat. The block is nothing more than a large stored heat source until 1 (Gary's timer) - 1 1/2 (my timer) hours after shutdown. Remember the solder on the PSG starts to melt at 140*, the block is 180* by definition of the water temp. The VP44 is aluminum and absorbs heat really well from the block. The blower floods the VP44 with OAT to keep the block heat from migrating to the VP44 frame and the PSG.
Bob Weis
Thanks for the prompt reply,
Missed you at the FL Get together. Mini Emer on That Sat...
Will a 3/8 Line suffice for a cooler in the VP44/Inj return line ????
Also, What pressure would the L/P have to produce to get a
After shut down Fuel flow for cooling the vp44,
I was thinking of running the L/P for 15 Minutes after shut down...
Thanks again,
Missed you at the FL Get together. Mini Emer on That Sat...
Will a 3/8 Line suffice for a cooler in the VP44/Inj return line ????
Also, What pressure would the L/P have to produce to get a
After shut down Fuel flow for cooling the vp44,
I was thinking of running the L/P for 15 Minutes after shut down...
Thanks again,
A 3/8" return line is pleanty. The requirements are not more than 10 psi in the return line. At one point in the stock return line the ID of the line is about 1/8". The VP44 is able to return 31. 5 gph when it is running full WOT rpm. 3/8" will take care of that easily.
The VP44 is a rotary pump. The pump has to rotate to put fuel through it. It is not possible to get fuel through it with zero rotation (shutdown).
IF that were possible then that would be the best cooling (use of fluid vs air, lubrication, etc), but not possible. That is why we went to external air flood cooling. The air cooling also allows air to go through the APPS pocket (if you drill a couple of holes in the top of the APPS pocket) to help cool the APPS as well (after all it is an electronic component).
Bob Weis
The VP44 is a rotary pump. The pump has to rotate to put fuel through it. It is not possible to get fuel through it with zero rotation (shutdown).
IF that were possible then that would be the best cooling (use of fluid vs air, lubrication, etc), but not possible. That is why we went to external air flood cooling. The air cooling also allows air to go through the APPS pocket (if you drill a couple of holes in the top of the APPS pocket) to help cool the APPS as well (after all it is an electronic component).
Bob Weis
I wonder if there would be any benefit by running electric fans instead of the clutch fan and having them run for 15 minutes after shutdown (or whatever time the batteries could handle without their life starting to be degraded).
Would that help the after shutdown heatsoak problem? Would the airflow affect the VP?
Would that help the after shutdown heatsoak problem? Would the airflow affect the VP?
I think that is basically what the guys found out that did install the ducting with the bilge fan. I think that the generalized electric radiator fans would not be to terribly sufficient due to the lack of ability to specify air flow directly at the VP. Also, it does need to be realized that the heat soak is coming from the engine and is being absorbed thru direct contact, and close proximity,of the aluminum body of the VP. I was surprised when Bob tried the misting idea and it did basically nothing. The bilge blower seams to be the best step forward regarding the heat soak... But at best it is only penetrating 1/2 way thru the VP. That may be enough to save the electronics a heating though.
I have run several types of heavy equipment with the 5. 9 cummins. There is no way I could imagine the electric fans could cool better than the mechanical fan at anything more than an idle. With that said - The Cummins is a work horse - we know this... . Most trucks on the road are not even coming close to giving the 5. 9 a workout. They are barely utilizing the engine. Loaded and combined I am moving @ 25k with mine and I have no overheating problems with my stock fan. I have the engine barely setup over stock for a 2003. I have tweeked it a bit since it is a 2001 HO. But none the less there is still plenty more room for growth in the power figures, and then more capabilities in effort. Of course that means more heat. With that happening I would consider adding a pair of pusher fans to assist in low rpm (engine) air flow. But at that point the travel rate of the vehicle and the air flow across the radiator should be sufficient to keep things cool. So it really isn't a matter of which fan you have but rather how much air is getting across the fins. If none of this were to work or matter to a specific situation... then a better or a second radiator would need to be considered.
Now to bring this full circle... . With all of that going on... the VP is tucked into a nice safe little corner with minimal air flow. With that going on the issue of electric vs. mechanical is pointless. This all goes back to the heatsoak and how to cut the heat effect down to a minimum. I think that Bob has spent a few kilowatt hours in brain exercise trying to get this under control. I believe what the VP really needs is an internal bypass with thermal monitoring timer to run an electric fan mounted to an external cooler. I am not sure if the resevoir in the VP would allow for a tap of a hard line for the cooling circuit, but that is the best I can come up with. The best electric fan setup IMHO is the bilge and duct setup due to it's simplicity and the expense. Sorry for the rant.
I have run several types of heavy equipment with the 5. 9 cummins. There is no way I could imagine the electric fans could cool better than the mechanical fan at anything more than an idle. With that said - The Cummins is a work horse - we know this... . Most trucks on the road are not even coming close to giving the 5. 9 a workout. They are barely utilizing the engine. Loaded and combined I am moving @ 25k with mine and I have no overheating problems with my stock fan. I have the engine barely setup over stock for a 2003. I have tweeked it a bit since it is a 2001 HO. But none the less there is still plenty more room for growth in the power figures, and then more capabilities in effort. Of course that means more heat. With that happening I would consider adding a pair of pusher fans to assist in low rpm (engine) air flow. But at that point the travel rate of the vehicle and the air flow across the radiator should be sufficient to keep things cool. So it really isn't a matter of which fan you have but rather how much air is getting across the fins. If none of this were to work or matter to a specific situation... then a better or a second radiator would need to be considered.
Now to bring this full circle... . With all of that going on... the VP is tucked into a nice safe little corner with minimal air flow. With that going on the issue of electric vs. mechanical is pointless. This all goes back to the heatsoak and how to cut the heat effect down to a minimum. I think that Bob has spent a few kilowatt hours in brain exercise trying to get this under control. I believe what the VP really needs is an internal bypass with thermal monitoring timer to run an electric fan mounted to an external cooler. I am not sure if the resevoir in the VP would allow for a tap of a hard line for the cooling circuit, but that is the best I can come up with. The best electric fan setup IMHO is the bilge and duct setup due to it's simplicity and the expense. Sorry for the rant.
Overall, there really aren't that many items underhood that suffer from typical underhood heat soak - and it's FAR easier to target and cool the specific few that need cooling, than to try to cool everything under the hood... 
PRout... . One other thing I forgot about is the thermal blanket idea. I checked the web site the guys mentioned (Bob I think) and they have some awesome items for sale. They even have a CO2 cooled block that would work awesome for the VP if there was a way to keep the CO2 cold. It would take a commited system similar to an A/C setup to make it full time and no need to recharge. However, It might be something to consider for chilling the fuel and the VP in extreme situations. They also have a CO2 spray bar that works similar to nitrous but is used to cool the intercooler. Let me know if you need the name... I think I have it saved in another computer.
Something I'm curious about. I thought running the stock LP with the engine off (bumping the starter) is supposed to purge air from the VP? Doesn't this mean the fuel has to go through the VP even when the it's stopped? Or am I all wet?
Karl
Only in very small volume - and even at that, depends on exact position of the internal assembly. The vanes of the VP-44 internal fuel pump (ahead of the actual injection pump assembly) are spring loaded, and very restrictive to fuel leakage past them and into the rest of the pump.
I (and I think Gary as well) have found the block heat does not dissipate significantly to a acceptable level until about 1 hour after shutdown with the hood closed. Gary has his timer set to 1 hour, I have my timer set to 1 1/2 hour (I tend to overdo most things and feel more comfortable with the extra 1/2 hour).
Less time, but I do not know how much with the hood open as I never really did a analysis with the hood open.
The bilge blower draws 3 amps so the amperage is not an issue. I find I replace the blower about 1 time per year (have changed 2 of them in 2 years, am on my 3rd). I put spade connectors on mine to make the change out easy.
The block should not cause a problem below about 100* as solder is not going to even get soft at those temps. So figuer out when your block get below 100* and you have your answer.
The bldge blower is not the only answer. However you can cool the block, keep the VP44 cool while the block is cooling, however. The key is keeping the Vp44 PSG from heat soaking so I use a bilge blower flooding it. As mentioned in the thread the bilge blower has a ram effect above 40 mph.
Bob Weis
Less time, but I do not know how much with the hood open as I never really did a analysis with the hood open.
The bilge blower draws 3 amps so the amperage is not an issue. I find I replace the blower about 1 time per year (have changed 2 of them in 2 years, am on my 3rd). I put spade connectors on mine to make the change out easy.
The block should not cause a problem below about 100* as solder is not going to even get soft at those temps. So figuer out when your block get below 100* and you have your answer.
The bldge blower is not the only answer. However you can cool the block, keep the VP44 cool while the block is cooling, however. The key is keeping the Vp44 PSG from heat soaking so I use a bilge blower flooding it. As mentioned in the thread the bilge blower has a ram effect above 40 mph.
Bob Weis
I'm thinking of installing an air cooler for the VP like you guys have, and was thinking about the timer.
I used to have Toyota Land Cruisers. They had a blower to keep the carburator cool after shutting off the engine. They used a heat sensor near the exhaust manifold which would shut the blower off when it dropped below 200 degrees. The point is they shut it off when the source of the heat had cooled. I was thinking that might work too.
Karl
I used to have Toyota Land Cruisers. They had a blower to keep the carburator cool after shutting off the engine. They used a heat sensor near the exhaust manifold which would shut the blower off when it dropped below 200 degrees. The point is they shut it off when the source of the heat had cooled. I was thinking that might work too.
Karl
That would work. I would base the temperature on when solder is still firm before it gets soft. I think about 100* - 120*.
True enough. Mine runs too long in the winter but long enough in the summer. The timer circuit we use is about $20 off the internet.
The key to this circuit is Gary's electronic genius of locking a relay closed when you have the engine running and then powering it from itself after you have turned off the DC power from shutting down for a settable amount of time.
Works well and very simple. My circuit board has been installed about 3 years. I replace the bilge blower about every 1 year. Common boat bilge blower.
Bob Weis
True enough. Mine runs too long in the winter but long enough in the summer. The timer circuit we use is about $20 off the internet.
The key to this circuit is Gary's electronic genius of locking a relay closed when you have the engine running and then powering it from itself after you have turned off the DC power from shutting down for a settable amount of time.
Works well and very simple. My circuit board has been installed about 3 years. I replace the bilge blower about every 1 year. Common boat bilge blower.
Bob Weis
Not quite ready for another heat related ECM thread just yet, but been working with a pair of spare ECM's lately. Earlier, during this thread, I tried attaching a temp probe to the backside - nearest the engine - of my ECM - and was sorta surprised that it's temp ran quite close to that of the engine block - or close to 200 degrees with engine shut down heat soak. I had thought that placement location of the ECM might better isolate it from underhood temps, but not so, it seems.
We don't hear of TOO many ECM failures - or know exactly what causes most of their failures - but at $1600 or more for a Chrysler replacement, it might pay to use some of what we developed for the VP-44 over into the ECM as well!
Along those lines, I plan to use what I already have on the VP-44, and will design and install a heat shield between the engine block and the ECM to shield it from engine block heat. I will take before and after temp readings, and see what that shield alone provides - same goal of less than 150 degree outer ECM case temp.
More later, as it develops...
We don't hear of TOO many ECM failures - or know exactly what causes most of their failures - but at $1600 or more for a Chrysler replacement, it might pay to use some of what we developed for the VP-44 over into the ECM as well!
Along those lines, I plan to use what I already have on the VP-44, and will design and install a heat shield between the engine block and the ECM to shield it from engine block heat. I will take before and after temp readings, and see what that shield alone provides - same goal of less than 150 degree outer ECM case temp.
More later, as it develops...
Last edited:
I've now installed an aluminum foil shield blanket between my ECM and engine block to isolate from heat - made a big difference, just like the same thing on the VP-44 did...
Prior to the heat shield, ECM case temp would run within a few degrees of engine block temp at engine shutdown - about 190-200 degrees. With the shield, slightly under 140 degrees in 94 degree ambient temp. There may be a slight beneficial effect from the VP-44 blower peripheral air stream - but that was there during the before/after test runs as well...
Might be worth the effort - it's a cheap install - and solid state ECM's don't like excess heat any better than VP-44 control boards do...
Prior to the heat shield, ECM case temp would run within a few degrees of engine block temp at engine shutdown - about 190-200 degrees. With the shield, slightly under 140 degrees in 94 degree ambient temp. There may be a slight beneficial effect from the VP-44 blower peripheral air stream - but that was there during the before/after test runs as well...
Might be worth the effort - it's a cheap install - and solid state ECM's don't like excess heat any better than VP-44 control boards do...
Does the ECM need to be mounted to the block at all? I haven't looked at it lately but couldn't it be moved to the frame, or someplace, using the exsisting wiring harness?
Along the same lines. . if someone made a jumper (where's timbo?) to extend the harness you could mount the ECM anywhere you wanted. I was thinking under the cab or even inside the cab.
Anyway... just thinking out loud. As Gary said you don't hear of too many problems with the ECM but it does seem like a bad spot to mount a computer.
Mike
Along the same lines. . if someone made a jumper (where's timbo?) to extend the harness you could mount the ECM anywhere you wanted. I was thinking under the cab or even inside the cab.
Anyway... just thinking out loud. As Gary said you don't hear of too many problems with the ECM but it does seem like a bad spot to mount a computer.
Mike
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