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

[Texas Diesel]

Got my IR gun in. Timing case was 184F. VP Bay 149F. Fuel cooler, 84F input, 74F output. Transmision case, 170F, FastCooler end plate, 150F (guess they really work). Powersteering pump body, 180F (WOW). Engine ECM 180F. Vp body, 140F. Fuel filter body, 78F.



OAT ~65F, 30 minute drive, unloaded.

 

[rweis]

As an example, my VP bay runs OAT + (5* - 10*) vs your 149*.



AT OAT = 65* my VP bay would have been 70* - 75* (about an 75* difference).



Now run the OAT up to 100* (+35) for summer driving.



Your VP bay = 150* + 35*? = 185* (ok, the temperature rise might not be linear, let's only add 1/2 of the +35* or 17* which puts you at 167*), My VP bay = 105* - 110*



I am about to get my VP temperatures down to OAT +- 0*, ie NEVER more than OAT*.



Now let's think about lubricity, fuel condition, air bubbles (easier to come out of 185* fuel or 110* fuel?), expansion of internal parts and tightness of resulting fit, etc, etc, etc. Oh, not to mention the fuel milage thing, but at $1200 for a VP44, that buys a lot of fuel mileage difference.



Sunday (1/29) I will connect the frame fuel return cooler system, and add a thermal blanket to the metal fuel return line from the VP44 to the engine T.



We're getting there,



Bob Weis

 

[Texas Diesel]

Good comparisons but I would like to know precisely where (what exact points) you are measuring. I have a 45F degree gradiant across the VP from the timing case back to the fuel distributor end.



For the bay temp I am shooting under the APPS.



We need to be checking EXACTLY the same places, just not sure how to communicate them.

 

[rweis]

I have an outdoor thermometer probe attached to the electronics bay cover and the readout is mounted in the cab so I can read it at all times. The exact point the probe is attached to the electronics bay cover is 1/3 down from the top of the cover and 3/4 of the way from engine gear case to fuel lines end.



I'll take some pics Sunday while I am in there puting the thermal cover on the fuel return line and connecting the frame mounted fuel return coolers.



On my fuel temp imagine a capital L. The short leg 3" (90* AN-6 on one end to the brass T, straight AN-6 on the other end to the Vp input connector) goes to the VP44 input connector (AN-6 metric connector replaced the banjo a long time ago). The long leg is the fuel supply from the low pressure system. In the corner where the two legs meet is a brass T. One end of the T is low pressure fuel feed, one end is the AN-6 NPT where the 90* AN-6 to the VP44 attaches, the middle of the T is the Westach temperature sensor mounting.



It is 3" from the VP44 so that the line from the low pressure fuel feed clears the power steering pump fill cover and is zip tied to the power steering pump fill cover tube then goes forward to the brass T.



Sunday I take some pics.



Bob Weis

 

[Texas Diesel]

Better data, 2 hour driving @ 60-65, unloaded, in the hills.



OAT 82F

ECM 130F

VP Bay 109F

PS Body 168F (I'm going to install a power steering cooler)

Fuel cooler inlet 103F

Fuel cooler outlet 93F

FF body 96F (+3*F than the return fuel temp) Still a nice drop because of the insulating washers but a thermal blanket might be a help if not a total PITA.

 

[rweis]

Texas Diesel - When I first started this thread I was seeing higher EBC (VP Bay) because I did not have a fuel cooler at that time. Your OAT / VP Bay was very typical of what I was seeing when I started cooling the fuel (~ OAT +25* to +30*)



I have tried alot of different things. Some successful some not so successful. I am getting to the end of things to try (my wife says "horay, now we can get back to painting inside rooms in the house).



Today I ran 260 miles at 65 mph (normall 51 mph is 5* cooler on the EBC just due to VP rpms). I could run at OAT +15 on fuel input and the same on EBC. At faster speeds the EBC temp is closer to the fuel temperature probably because it is circulating faster through the VP44. At slower speeds the EBC is generally 2* higher than the fuel input temps. And that would make sense.



I finished installing the return fuel coolers inside the 4" ducting and there is a significant difference between the input and output return fuel temp. I put the hottest return fuel in the last cooler toward the rear and then the second cooler (which is after the first cooler in sequence) closer to the blower so the hotter fuel temp would not heat the second cooler. I will get readings on the temps in the next day or so.



I can run OAT +10* at slower rpms (1400) and OAT + 15* at faster rpms (1875). I can also slow down and see a cool down in the EBC. I put the blower in the return fuel line so it would cool at slow speeds (around town, stuck in traffic). I think it is important to have passive as well as powered cooling for that purpose. I will take difference readings, but think that maybe ducted cooling is more effecient than mounting a fan on a large flat cooler. Harder to mount, but I think the volume that passes is more concentrated and maybe more efficient.



I am going to run with this configuration for a while and see how it goes. I can live with OAT + 10* or 15* for the EBC (110* = not hotter than 125*). I think there are dimminishing returns starting to take effect. I do not think it will ever be possible to get the temps to OAT (asympotic lines and all that sort of concept).



I am at work but will get pics in a day or so.



Bob Weis

 

[Mundgyver]

Bob, are you keeping track of your MPG as you make these changes to your setup??



-Wally-

 

[rweis]

I think the lowering fuel temp is worth about 1 - 2 mpg. Roughly about the 10% the trucking article had. As I recall before the experimentation I was getting about 27 mpg on the overhead console (I know the # is not right, just a benchmark). Now I get 30 - 31 on the same stretch of road (5 miles totally flat) at the same rpm day after day for months.



It is not as incremental as you would think. When it went from hot fuel (fuel return in the cannister) no mods, to fuel in the high ##'s to low ###'s was the biggest gain. The tweaking here and there has not done much different.



On hand calculating average mpg it went from low 15's to high 16's and occassionally a low 17. #. So I would say that about 1 - 1. 5 mpg is realistic. Not a lot, but some. Now I can WOT it and get almost zero smoke. If that has anything to do with it. I have towed with it once about 200 round trip and the tow overhead was consistently +1 mpg, but terrain has so much influence in mpg, unless you are on the same route time after time (like going to work every day) it is hard to compare.



Bob Weis



I am going to experiment some with coolers inside ducting vs a flat plate cooler with fan on the fuel input line. Seperately, I think I will also do an exchange hookup with a 24" fuel cooler across the front radiator system instead of the copper tube cooler and see what does. Those are my last 2 experiments I think as I know I can do OAT and NOT more than 15 and that is a whole lot better than OAT +50 where I started OEM.



Interesting temp reading from Texas Diesel on the PS pump. I'll have to check that out. Would not surprise me though. Overall temperature management Im not too thrilled with DC (transmission towing and in reverse, fuel, PS?, engine coolent seems ok, oil seems ok, fan gets flakey, breather bottle is a joke and location is a disaster).

 

[Gary - K7GLD]

Seems to me that concentrated effort to focus use of cooler air from the front of the truck for fuel cooling purposes would deliver maximum benefit, as opposed to use of air drawn from further back under the truck where airflow is somewhat heated by the engine and radiators.



Might be pretty obvious to some, but worth mentioning...

 

[rweis]

It is hard to find a way to get clean cool air.



For the VP44 cooling the blower is mounted in back of the front bumper, which I think is a pretty good spot.



For the return fuel cooling, I stacked the coolers with the hottest cooler last and draw the air from under the running board away from the central engine / transmission heat core.



For the H7B w/fan back in the drivers bed pocket (which I think I will change), right now I draw from about 1/2 way back down the drive line and that is not a good place probably. Here is where I might change to a more cooler inside duct concept where I can choose where I draw the air from.



I like the ducted idea. You can force air regardless of forward speed. You can get the air from where ever you choose (within reason). You totally enclose the frame type cooler and you can have access cutouts and just tape them over after installation with waterproof aluminized tape.



Just finding the place to put the ducts is a little challenging. The drivers side underneath looks like a oil refinery with all the plumbing.



Bob Weis

 

[Mundgyver]

Need to build these cooler into a set of Nerf-Bars

 

[Texas Diesel]

Bob, what are you using to record your readings? I made a simple Word Document that holds 4 sets of complete readings. I would be happy to email it to you for your review/additions/use if you would like. PM me if interested.



I printed out 20 sheets and put them in a 3 ring binder to keep in the truck as a sort of log book.

 

[rweis]

Sure, send the log. doc The more on the same page we are the better data we have. The more we take the same readings on different equipment in different locals the better. -- email address removed --



I have NO parental interest in any of this, I just want the VP44 to last more than 52k



Build a cooler into the nerf bar?, now that is a cool (pun intended) challange. Why not?



Bob Weis

 

[Texas Diesel]

You have mail. If you like it feel free to distrubute.

 

[Mundgyver]

Most nerf bars are hollow and used for step ups. Build one into a heat exchanger unit by flowing air through it with internal piping for fuel and it is out of the way, protected and does not clutter up any engine compartment space



The only question is, would it be legal by D. O. T.

 

[rweis]

Oh, BTW, I did change the fuel return line to the tank. I disconnected the fitting (16 mm wrench) and bracket brace (10mm bolt) at the bottom of the engine T (left the injector and VP44 return alone). The fitting is a flare nut with a rubber packing that further seals the flare.



When you first remove the flare nut you can feel resistance (from the packing it turns out) and are not sure exactely what is going on. As the packing backs off the flare nut suddenly becomes a "normal" flare nut removal.



The OEM return line has a finger clip on both sides and has like a double flare on the metal tubing. The finger clips clip around the double flare.



I was courious if the double flare was indeed a double flair or a solid ring. It turned out to be a double flare. After I removed the double flare so an AN-6 hose could slide up on the metal tube, I had about 2 1/2" of tube remaining for sealing. The tube seems to be a little bit less than 3/8" OD but only by 1/32" - 2/32". The AN-6 hose is held in place by 3 small hose clamps. After tightening the hose clamps tight I tried to pull the AN-6 hose off. Could not even budge it rotationally.



I reattached the bracket that holds the common fuel return part (the part I took off) and worked tightening the bracket and tightening the flare nut back and forth to ensure the flare nut was threaded correctly and the bracket was positioned correctly. Went back in without a problem.



I have removed my OEM ff and had pleanty of room to work, just had to lay on the valve cover (up close and personal) to be comfortable working.



The OEM fuel line seems to be a teflon tube like the tube you run water to your refridgerator (except black). That tube is inside a relatively light weight outer tube that fits over the inner tube very loosely (gap between tube and cover is about 3/16" - 1/4". The teflon tube is sweged inside of the 5/16" (OD) metal fuel return line. I figuer that the ID of the teflon tube is 2/16" - 3/16". I will cut it and measure it to be sure.



Anyway, that is what I found and saw. I now use AN-6 to return fuel to the tank through fuel coolers.



Bob Weis

 

[rweis]

Today I thermal wrapped my inline ff. One drive only, but around town which seems to be worse case, another 2* - 4* shaved off the fuel temp. Nothing is a silver bullet. Every single thing you make cooler contributes to cooler fuel.



I have been thinking what this thread should wrap up into:



1. Try to get all fuel related components out of the engine compartment because of heat issues. Anything left thermal wrap it well.



I got the OEM ff out, the lp was on the frame for different reasons, I thermal wrapped the VP44 return line to the engine T, I thermal wrapped the input fittings to the Vp44, I thermal wrapped the VP44, I ran a blower directly to the VP44 that runs during ignition on and for 128 minutes after shutdown to stop VP44 heat soaking.



2. Thermal wrap any fuel related component that is not in truely free flow OAT air.



I have a final inline ff and wrapped that today. It is mounted on the front crossmember under the engine fan outflow and picked up heat from the engine fan flow.



3. Fuel cool input fuel. I cool the fuel out of the tank to the RASP.



4. Fuel cool return fuel. I cool the Vp44 return fuel to the tank (see in duct coolers above).



5. Consistantly record what ever temperature you want so you can see what good / bad changes you make on the temperature.



6. Cooler fuel is probably better (able to cool the VP44, less entrapped air?, better lubrication). I can not find anything that hotter fuel is better. Min fuel temp probably should be cloud point +10*.



I am going to run this configuration (OAT +7* to 10*) through the summer and will bring this thread up this fall. If anything significant surfaces I will report that sooner.



Bob Weis



Thanks to everyone for being patient and contributing and maybe we all learned something I hope.

 

[Texas Diesel]

Bob, I think this is one of the most interesting threads ever started. Let me be the first to thank you. Hopefully someday, this thread will be condensed and included in the print TDR magazine.



One thing, REAL progress to cooler VP temps can be obtained with just a return fuel cooler and insulating washers (4) to insulate the FF from conducted heat. The single biggest step is to insulate or relocate the FF off the cylinder head.



But, like you pointed out, there is no silver bullet, just incremental steps towards lower VP temps.



You have discovered a real solution to longer VP life.

 

[rweis]

I would thermal wrap the ff as well. I used thermal blankets that are a mylar (tough) metal foil reflective on one side and a high (2000* radiant) heat barrier on the other. I got mine (Design Engineering Inc) at my auto parts store (they build race cars at night, ).



This am my routine drive OAT=45*, fuel input temp =50*, EBC =52*. When I started this project it would have been the OAT=45*, EBC=95*.



Cooler running VP, cooler fuel, lubricate the fuel, clean the fuel (no water / no particulates), no air in the fuel, as close to Bosch specs psi as you can get, keep the VP cool after shutdown, bigger feed lines (3/8 ID).



Basically redesign the whole fuel system:



(going to rebuild the fuel cannister this summer(thanks CStewart)),

bigger lines (AN-6),

better fuel delivery (full flow fittings, no banjos),

fuel and fuel component temperature control (fluid coolers (w/ or w/o fans) & component thermal blankets, get the OEM ff off the block),

better lp pump (Fass, RASP, pushers, whatever)

Bosch spec delivery psi (13. 5, Brett @ II)

Control the VP heat soak (raise the hood, or blower)



That about sums it up



Bob Weis

 

[ceastmen]

Nice Job

Bob, I've followed your posts and added my 2 cents a time or two.

Just wanted to say that this is what TDR is all about, nice job thanks for your time and information. I will be adding a cooler for our summer family re-union this year in Bend Oregon.

Chuck E.