Towing with a Powerstroke 7.3L (expectation/realistic)

[Kamyo91]

I'm looking at upgrading to a 11.5K loaded fifth wheel.

I currently tow a 6K TT.

Truck is Bone stock except for (DP infinity tuner and a 6.0L Trans Cooler)
2000 F250 7.3L CCSB SRW auto 4x4 Lariat 3.73 with 90K miles.

I live in the Pacific NW so passes and grades are part of life here.

So question goes to you guys with turbo 7.3L towing around 11-12k
whats your speed, RPM, gear when ascending and most important what
have you done, or has been done to your truck to accommodate the pull.

Thanks in advance.

[marcsbigfoot20b]

Like others have said, its all about the upgrades and tune on the 7.3

For $1000 you can get ceramic coated bellowed up pipes, Riffraff or WW2 turbo wheel, and bigger exhaust. That takes care of most EGTs. Now get a good tune that is changeable on the fly like the PHP Hydra or DP Tuner plus the quiet Ford factory AIS airbox for another ~$350 and you are set.

Those are the mods in my sig and I can pull 7500 lbs at safe temps with the 80 hp tune up 8% at 75 mph all day up at 6000 ft or more.

[WTP-GC]

Wes Tausend wrote:
...

The odd thing is why would a relatively large displacement such as 7.3L develop excessive EGT's if newer, smaller displacement diesel engines do not also do so under the same heavy load conditions?

It has been my understanding (based on tons of research) that the 7.3L PSD in a stock configuration is incapable of producing EGT's high enough to warrant concern. However, the very minute you install larger injectors, this becomes a problem. More power upgrades from other sources only exacerbates the problem.

There are simpler ways to lower your EGT's without going through the expense of an intercooler. From what I've read, most people are not happy with the EGT decrease after installing an intercooler on their OBS 7.3L, which is one of the reasons I haven't done this. For the work and cost of an intercooler, one would expect more than a 50 degree difference (which is about what most people have reported).

I chose to make other improvements to decrease EGT's, which consequently add more power and efficiency. There are so many things that go into making this engine perform at an adequate level that I have to wonder if those people who report negatively about its towing characteristics don't have their truck running right in the first place.

For example, one of the biggest PITA things to do on these trucks is to replace the up-pipes. However, if your up-pipes are leaking (which is extraordinarily common on the 7.3L PSD), then you will be robbed of power (boost) and fuel efficiency, while unnecessarily running up your EGT's as you pour in more fuel (in an attempt to make more power). Replacing those on my truck made a huge difference. Also, gutting the EBPV and replacing the stock turbo wheel also made a big difference. When you do all that, replace the original boots on the turbo manifold y-pipe. Anything you can do to "contain" and "create" pressure (for boost and power), the better off you are. Put in a larger exhaust and a tymar-style intake, and you're making even more headway.

Though I've upgraded my TV for towing my 5er, back when I used my 7.3L PSD for this purpose, it was more than adequate for the OP's purpose. I can maintain 4th (OD) at 65 MPH on generally flat or moderately hilly terrain and was never disappointed to back down to 55 MPH in 3rd gear when in the mountains. Keep in mind that I tow a lot of big trailers for my business and since business is good I could easily justify the upgrade. Otherwise, I'd still be using my OBS 7.3L PSD for RV tow duties.

[Wes_Tausend]

...

The odd thing is why would a relatively large displacement such as 7.3L develop excessive EGT's if newer, smaller displacement diesel engines do not also do so under the same heavy load conditions?

The answer must lie in choosing the appropriate "tuning", intercooler and turbo setup. So if one is determined to beat newer diesels to the top, it must just be a matter of more precise 7.3L tuning and some well thought-out parts that are still going to cost a lot less than a new truck with a puny engine displacement.

Quality parts and advice like Banks and some others come to mind. As an example, for 7.3L towing, Banks is almost certain to recommend a larger intercooler, or at least intake fluid injection (propane, methanol etc). This seems like the first place to start from an engine that is expected to perform more than the usual over-fueled stop-light-to-stoplight show-boating... an engine that is expected to perform at heavy uphill towing.

My parts choices, if I ever modified a 7.3L, would also possibly only include a larger turbo down-tube, saving plumbing bucks from muffler on back simply because the exhaust needs less and less volume as it cools downstream anyway. And on the other end, a better intercooler reduces the need for a downstream larger intake simply because the better cooled charge is denser, more compact.

For me, sound control is also a major issue after the first few minutes, which is the reason I would not prefer a silty K&N and noisy new airbox. I got more than my fill of extended over-the-road loud diesel thrumming at work.

And finally, just like our locomotives, transmission heat is a major concern and something to consider upgrading as a package. Banks usually recommends this too.

Granted, the old 7.3L runs dirtier nox-wise, but that is an EPA problem only. Admittedly, new smaller engines get better economy too, at light empty load that is. And some newer engines have somewhat more durable internals for extreme competition levels. But there is still no replacement for displacement when pulling. And at sane rpm levels, stock crank and rods are not a problem for the 7.3L.

Wes
...

[Highbeam]

For the OP, if he is still watching. Don't do it. 12k behind your (same as mine) truck is too much for our passes. Blewett pass is tough with even 7500# trailer.

Mine is 7.3, 2000, Ford AIS intake, 4" exhaust, tuner, trans cooler etc. I overtemp on EGT before I run out of "power" meaning I have to back off to 50 mph instead of 60 to keep it from melting down with only a tall TT.

[Wes_Tausend]

BigToe wrote:
Thank you Glen (SoCal) for your informatively detailed insights on living with your new to you medium duty truck.

And thank you Wes, for connecting the dots on a good take away lesson... which amounts to checking the heater plenums to extract all of the leaf debris, in the cases where the vehicle's HVAC fan resistors are exposed to such debris.

Ugh. Not a job I look forward to.

BigToe,

The job isn't necessarily as bad as it could be. On my Mazda/Ranger, I believe I cleaned the plenum by simply removing a few screws holding the heater motor in place on the firewall and vacuuming debris out through the gaping mounting hole. A quick peek reveals that my Excursion (same as F-250) heater motor is mounted the same way. If I remember, the Impala was a lot more difficult, requiring me to remove a failed heater motor from under the crowded dash. That was Ugh.

A field mouse entered my dear wife's Prius heater plenum by sneaking in through the recirculation vent (I assume). The outside intake grills are fairly critter-tight, but not seed-tight without actual foam (think RV A/C cabin intake, same). During an oil change, the Toyota dealer found the nest when he checked the cabin filter which was chewed into a nice fleecy fuzz suitable for babies.

OTOH, one fall a tree squirrel built a nest under my Excursions hood judging from the size of sticks used. Unfortunately he also chewed a hole midway in the side of my brand new battery (ick), and several vacuum lines. I only found the nest after a couple of short trips and it suddenly didn't start at all... dead, leaky battery. They wouldn't warranty the still-new battery but they did smile. I suppose I could have tarred it up like the old days and refilled the acid. 🙂

Wes
...

[SoCalDesertRid1]

Marty,

The truck was ordered new, to be built as a fire truck. I got the original order/build sheet with it, detailing all the options.

They stripped most of the firefighting stuff from the truck before it went to auction. It carried a skid mounted fire apparatus that had the pumps, hoses, tank, generator, storage boxes, etc. There was a large electronics console between the front seats, which they removed, as well as all the emergency lights on the roof and fenders.

I don't see a spark arrestor on the exhaust. If it was there, they took it off.

I have some pics of the truck from before I got it. They're stuck in my old phone now. One of the pics was from when it was a working fire truck, which I found on the internet. Most were pics taken for the auction website, after they stripped it.

[blt2ski]

Glen,
That sounds more like a fire truck addition than a normal Navistar MDT or equal addition. As my 92 4600 does not have a lot of those items. Then again, I have the IDI 7.3 diesel too! Might have something to do with gvwr. BUT, swag would be it is an off road pkg with spark arresters etc for forest service fire work.

Marty

[SoCalDesertRid1]

Thanks guys.

I agree about the auxiliary transmission being a good choice for dual-purpose operation (towing and empty use) with a smaller engine. Or a 2-speed rear axle, if the vehicle is 2wd. I've been saying for years that I wish the 3 brands would go with some kind of 2 speed gearing choice, because having only one final drive ratio is always a big compromise that doesn't have to happen.

On the International, I have another high gear available in the transmission (0.65:1 6th gear, versus the 0.75:1 fifth gear). I just need to get it enabled. Then I can cruise at a faster road speed, without raising my cruising rpm. Allison wants $1600 to re-write the transmission programming to enable the 6th gear, and change the manual shifter unit to the 6 speed version.

I had been doing the weekly 'rat check' of the F350 before it caught fire. I do that on all my vehicles, after my experience with the gas engine F350's injector wiring. The truck was clear of rats the last time I had checked. It's possible a rat may have got in, in the last few days before the fire.

I notice on the International, the Forest Service added a mesh screen over the cabin air intake vent in the cowl, to keep leaves, etc out. I'm happy about that. There is also a heavy duty grille gaurd, I assume to keep tree branches out of the radiator. As well, there is fire insulation over some things under the truck, presumably to keep the truck from catching fire as they drive over burning embers on the ground while fighting fires.

[BigToe]

Thank you Glen (SoCal) for your informatively detailed insights on living with your new to you medium duty truck.

And thank you Wes, for connecting the dots on a good take away lesson... which amounts to checking the heater plenums to extract all of the leaf debris, in the cases where the vehicle's HVAC fan resistors are exposed to such debris.

Ugh. Not a job I look forward to.

[Wes_Tausend]

...
Glen,

That is a very interesting story about your trucks, especially the '01 International 4800. As far as hi-jacking, much of this is still related to any towing truck. Thanks for sharing it.

A commercial duty truck certainly makes sense for you by far. So does adding a less-clumsy run-about Ranger as a general errand driver.

For occasional do-it-all truck use, with the relatively narrow rpm power band of early diesels, I would still suggest the OP consider an auxiliary two-speed transmission. Even on 4X4, it seems this may greatly improve the 2-wheel drive 3.73 gearing problems of towing a somewhat larger RV, plus add a bit of fuel economy when empty. I don't believe the auxiliary transmission would be a problem... provided one could return to 1:1 when using slow speed 4X4.

If you ever go CDL, and increase loading/towing with the 4800, you might have already considered the advantage of upping your 5-speed to a 10-speed using the same principle. One would want to be certain in all cases, that the auxiliary two-speed transmission were up to snuff for whatever load, probably a Brownie type in your case.

Other than the initial cost of the auxiliary two-speed transmission, it seems win-win all around.
----------------------

I also have a comment about the fire in the F-350. I owned a '94 Mazda B4000 (same as Ford Ranger) for a number of years. One winter day, as I left my house, I smelled (wood?) smoke coming in through my fan-vent system. It turned out to be the fine seeds from our Weeping Birch tree. I assume they accumulated naturally by falling through the coarse mesh on the air vent intake right in front of the windshield. Rain casually leaks in too, but it normally runs out the bottom. We once had a 2000 Chevy Impala where this drain plugged, same seeds.

As far as I know, all modern Fords (and probably many others) have the same speed control for the fan. On high, the fan runs at full rpm. On lesser speeds, the power is switched to various series resistors, strategically located in the heater core/evaporator plenum. They may glow red-hot, but intake air normally cools them.

In my case the seeds built up until the hot resistors were hopelessly buried and then started to burn. Fortunately the fire quit when I frantically shut the fan off to stop the thick cab smoke. I cleaned the plenum and determined I would thereafter have to do one of three things: 1) clean yearly, 2) install a fine-mesh foam vent intake filter (wife had one on her Corvette), 3) or remove the tree; which I did since it was dying anyway.

Wes
...

[SoCalDesertRid1]

Ok.. I guess we're hijacking this thread then. I think the discussion about the 7.3 was about over anyways when I first posted on the topic, so here goes...

Yes, the F350 was loaded for bear with welding equipment. I don't carry acetylene on the truck. I carry propane instead. Propane is safer, cheaper and more readily available to refill. I only use the torch for cutting and heating, no welding (propane has no shielding gas properties is not able to be welded with). I was also carrying a gasoline can and 2 each oxygen and argon (inert shielding gas) cylinders.

Fortunately, the fire department got to the truck before the gasoline, propane and high pressure cylinders could go kaboom. The truck cab and everything forward of that was a total loss, but everything inside the utility body boxes was saved and I had only minor smoke inhalation and minor burns on my hands. God had my back that day.

I think the lessons to me were, always be prepared, count my blessings, God has a plan, and it's only a truck it's replaceable. 🙂

Since it took me so many months searching to find a good condition, low mileage, diesel, 4wd, dually, extra long wheelbase (had an 11' bed on it) old body style F350 when I bought that one up in Idaho, I knew finding another one would be much harder, some 4 years later. I was also tired of driving overloaded F350's, with small brakes and rear drums that are always going out of adjustment. I definitely wanted something bigger than an F350, with very good brakes.

I looked seriously at '99-'02 F550's with the 7.3 diesel, 4wd and long wheelbase. I found a few, some even crew cabs, but none that really made me want to buy. The F450/550 cab/chassis trucks are still small trucks, extra heavy duty pickups, if you will. I really wanted something that was truly a TRUCK.

So I considered the old Ford L-Series and more current F650/750, GM Kodiak/Topkick, Freightliner M2 and International 4000-series. Finding any of those trucks with 4wd and crew cab was almost impossible, except for the Internationals. I found alot of 4800/4900 4wd's that were power company boom trucks and oilfield drilling rig trucks. Then I found this 4800 ex-fire truck, with 4wd and crew cab, very low miles/hours and just the right wheelbase length, with a nice flatbed already on it. I knew that was the one.

Yes, everything about the 4800 is BIG...

The cab roof is 9 feet high, the cab floor is about 4 feet high and the hood is about 6 feet high. The cab rear bench seat is at least a foot longer than my crew cab F350's rear seat. There is tons of room inside the cab, with nice flat floor all over and lots of rear seat leg room. The Dodge Mega Cab is tiny by comparison.

The flatbed deck is over 4 feet high. I put a set of steps on the rear to get up and down from the bed. Tires are 42" diameter (11R-22.5, same size as class 8 tractors and busses). It's a climb to get up into the cab, but there are nice 2-level steps built onto the 50 gallon fuel tanks and plenty of grab handles to hang onto.

The DT466 engine, although only 22 cubic inches more displacement than the 7.3 Powerstroke, is physically a much bigger and heavier engine, longer and taller. The Allison 3000-series transmission is class 8 semi tractor sized, much bigger than the Allison 1000 used in the GM pickups. The Fabco transfer case is giant, heavy, cast iron. The 12K Fabco front and 21K Dana-Spicer rear axles are giant hunks of iron too. The huge Spicer rear makes a Dana 80 look tiny.

The brakes are huge air operated drums. They work awesome. The transmission also has a hydraulic fan retarder on the back of it, with a separate foot pedal in the cab next to the brake pedal. The retarder works great, almost as good as the brakes. This truck stops much better loaded and pulling the trailer with the trailer brakes disconnected, than F350 ever stopped, even when it was empty. I'm very happy. 🙂

The truck's frame channels are 8 inches tall, very thick and about 3" wide. The frame is straight, front to back, no bends in any direction. I don't see any weak points in this frame, it's solid. I have welded on cracked 3/4-ton, 1-ton and 450/550 truck frames. The pickup-based frames are tiny, compared to the big class 6/7/8 size truck frames.

The spring packs are huge on both axles. The rear overload packs are about as stout as the main rear spring packs on the old F350. The truck probably rode much softer when it was a fire truck, loaded to it's full 33,000 GVWR, carrying 500 gallons of water and all the other equipment and crew of 5 fire fighters. Now it's 13,000 lbs under the GVWR and about 10,000 lbs under the rear axle weight rating. But that's what I wanted, a truck that wouldn't be overloaded, or loaded anywhere near its max capacity.

The truck is heavy. I weighed it when I first got it, before I started building it into a welding truck. With just the cab and 12x8 flatbed, it scaled 16,000 lbs. My old F350 scaled about 8000 lbs with just the cab and 11x8 flatbed. All loaded up, the F350 weighed 13,000. I'm not yet done adding stuff to the International, needs a bigger crane, a couple more boxes and upgrade the gas welder to a bigger diesel. It weighs 20,000 so far, carrying all the same equipment I had on the other truck, minus the utility body. I went with gang boxes and side boxes this time. Saved about 1000 lbs and am better organized and easier to access everything.

The truck rides hard, empty or loaded, harder than either of my F350's rode empty, with their extra heavy duty rear springs. It would be nice if the truck had an air ride cab. I may upgrade to that in the future, as it was a factory available option. It has nice air ride front seats, which do help alot. An air ride rear suspension would be nice, but I prefer the durability and simplicity of leaf springs.

The heavy suspension handles like it's on rails. No body roll or sway, no matter how twisty the road is. The F350 dually handled corners good too, very little roll and better than my single rear wheel F350, but not as good as this one. It's rock solid.

Steering was scary when I first got the truck. The Forest Service had rear drive-only tires on the front axle, with huge chunky knob treads. They squirm alot and like to follow every rut in the road and change directions with every bump. I guess they got away with because they are a government agency and it was an emergency vehicle. DOT regulations don't allow drive-only tires on the steer axle.

I put highway rib steer tires on and steering improved greatly. It's still a bit squirrelly and has some bump-steer, but it's much safer now on the bad highway roads we have around here. I'm going to look into a better stabilizer shock and have the toe-in alignment checked, to see if I can get it a little better. It might just be the nature of these 4wd heavy trucks.

Because of the 4wd front axle and the long wheelbase length (about 190" with the crew cab and 87" cab to axle length), it doesn't turn very sharp. I expected it would turn sharper, because of the full-width front axle, but it doesn't. Both my 4wd F350's, with 161" and 168" wheel base lengths, turned slightly sharper than the International.

Parking the truck is about the same as either of my F350's. It's longer, about 25' long, and 8' wide, same width as my old dually F350. The F350's are about 20' long. The truck doesn't fit in any parking spaces at the grocery store LOL. I take up 2 or 3, or sometimes even 4 spaces, way out in the boondocks, and walk. That's what I did with the old truck too, so no big change with this one.

I wouldn't want to drive the International as my only vehicle. I wouldn't want to only have the F350 either. I drive my little Ranger most of the time for personal use. It has good gas mileage and gets around town easily, can park it anywhere and is comfortable, quiet and easy to drive.

As far as fuel mileage goes, the International gets about the same as the old F350 diesel, 10 mpg loaded. It gets that same mileage though, while also weighing 7000 lbs more than the F350, and has TONS more towing power on the hills than the 7.3 could ever hope to give. That big DT466 engine is barely breaking a sweat most of the time, whereas the 7.3 was huffing it often.

I like the Allison transmission. I wasn't too keen on the idea of another automatic juice box at first. I really wanted a manual trans, with granny low first and reverse gearing. It's tough to find these trucks with the manual though. Most have the Allison. The 4900's and some of the higher GVWR 4800's have 9spd and 13spd Eaton-Fuller high/low air shift manuals, which are truly heavy truck transmissions. I didn't quite want that much tranny. There is a 7-speed manual shift, no air, not high/low, that I found on some 4600, 4700 and 4800 trucks. However, that trans was not rated to handle the 850 torque rating of the DT466E-HT. I'm not sure it is rated for the regular DT466E with 660 output either.

I preferred to have the 7 speed manual instead of the auto, if it were available with this engine. I've grown to like the Allison though and I'm happy with it now. It has a low first and reverse ratio that I like and shifts predictably and I love the retarder. That retarder is reason enough to have the Allison.

On the legality side, because of it's 33,000 GVWR and the fact I use it for business, it can require a class B or A commercial license, if I register it for it's full GVWR, or a higher GCW. I have it registered for 24,000 GVW/GCW and will upgrade that to 26,000 on my next renewal. Keeping it registered under 26,001 lbs means no CDL required.

The truck weighs 20,000, so that means my trailer can't weigh over 6,000, or I cross that magic 26,000 GVW/GCW number. Then I would need to get the class B CDL and if the trailer is over 10,000, I would need the class A CDL. So I have to watch how I load the trailer if I don't want a CDL.

Because I use the truck for business, and Arizona is one of the 22 states that requires DOT number registration for any business-use truck over 18,000 registered GVW/GCW, even though the Federal DOT doesn't require it for trucks under 26,001 registered GVW/GCW, I had to get the DOT number. It was a hassle, but didn't cost anything to register the number.

The DOT number is not specific to the truck. It is specific to my company. I can use the number on any quantity of company trucks (although I only have one official company commercial truck now). If I sell this truck, the DOT number goes on my next truck and will be removed from this truck, so the next owner isn't running around with my company's number on his truck.

Having the DOT number also required me to get a DOT physical exam and medical card, which renews every 2 years. It was no big deal.

Because of the DOT number, I'm also required to keep a driver qualification file in my records for every driver of commercial trucks in my company (which is just me). I got a DMV copy of my driving record and that fulfills the qualification requirement, as far as I know.

The DOT registration also requires me to display my company name and location, in addition to the DOT number on the truck. I had planned to put a company logo, etc on the truck anyways, so no big deal. I had 'not for hire' magnetic signs made, to cover the DOT number, for those times when I use the truck for personal, non-business purposes.

Overall, I really like the truck. I'm very happy with it. I'm not thrilled about all the red tape that came with using a truck this size, but that's life I guess. You got to pay to play (or work, in my case). 🙂

[BigToe]

What a story. How awful. I recall that you carry a lot of welding equipment in your truck... and acetylene cylinders act like unguided missles when engulfed in extreme heat. Very astute of you to keep checking your rear view mirror when driving, given that you had no sign of trouble in the cab.

I'm trying to think of a take away or a lesson to learn from your misfortune, but cannot come to any conclusion other than "..it happens", and perhaps to stay out of Arizona during the summer, which I already try to do.

Sounds like you've replaced your truck with a beast. I don't think any of the gear heads on this forum would object to you describing your replacement truck in a bit more detail... especially comparing the driving experience of a true medium duty chassis vs a light duty chassis. Now that so called "heavy duty" light duty chassis cabs and pickups are in the $70,000 range when new, the prospect of getting a true medium duty truck probably enters the minds of more prospective personal truck owners with heavy trailers than ever before.

But I have observed several members on RV forums over the years who "graduated" from a 250/2500 to a 350/3500 dually to a 450/550. However, when stepping up to the near equivalently rated, but larger bodied 4500/5500 Kodiak, or the higher rated International, Freightliner, Acterra, etc true medium duty trucks, these same buyers eventually yearn to return to the smaller, more pickup like style tow vehicles.

I drove an F-650 SuperCrewZer a few times, and while I had no doubt that it was a more capable truck than my F-550, there was something about the heft of the F-650 that simply felt like "too much" truck to live with and get around in without a trailer in tow. I think this sensation, whether it makes logical sense or not (the F-650 had a tighter turning radius than my F-550, for an example of illogical reasoning) is partly to blame for the 4500/5500 Kodiak/TopKick line being shuttered for lack of sales, even while it was arguably functionally superior to the more pickup like 450/550 chassis cabs of equivalent GVWRs.

Anyway, feel free to post more about living with your International 4800 4x4 CrewCab with the DT466. Everything about that chassis feels like an order of magnitude bigger than a crew cab 4x4 F450 of the same model year, yet I'll bet the 4800 turns tighter, and might not even be as long, even with the crew cab, depending on CA length.

[SoCalDesertRid1]

Hi Big Toe,

The fire started in the HVAC system. It caught on fire as I was driving it down the highway. Was probably on fire for a couple miles, before I realized it. All the smoke was going down and under the truck. No signs of fire could be seen from the cab while I was driving. I saw the smoke when the engine started losing power and I looked in the mirrors before pulling it off the road. The AC/heater box in front of the firewall was the primary area I saw in flames when I first opened the hood.

I have a theory about how it may have started. Don't really know if it's right. I was running the AC that day. It was 117 degrees and about 4 in the afternoon when this all went down.

I think the large resistor for the AC system, which is either inside or attached to the heater box, failed or shorted out and burned up, which probably lit some leaves/pods afire that a rat had likely packed into the heater box area. We have packrats out here. They ate up the injector wiring on my other gas engine F350 about a year before the diesel F350 burned down.

There was a massive electrical short going on, as the whole wiring harness under the hood was smoldering at the same time the heater box was afire. By the time I stopped, the heater box had already lit the plastic inner fender well on fire, which soon collapsed onto the tire and lit the tire on fire. It was a gonner from there.

I had 3 fire extinguishers on the truck. None of them worked. 2 must have had leaking pressure valves, as they were full of retardant, but there was no pressure to shoot it out with. The other, I think I had used partially awhile earlier and forgot to have it refilled.

If I could have quickly disconnected the batteries, and had at least 2 working fire extinguishers, I may have been able to save the truck. Every vehicle I own now has working fire extinguishers, 4 for the new truck. I added battery quick disconnects to all my vehicles too, except the International, which I haven't found a disconnect for yet that is big enough to handle it's 3 giant batteries.

That is a healthier increase in horsepower than I had thought for the newer 7.3 trucks.

I probably have the wrong term when I said turbo waste gate. It may very well be called exhaust back pressure valve. Anyhow, it worked alright. The programming is apparently a common upgrade modification for 7.3 Powerstrokes. My transmission guy did the modification at the time he rebuilt and reprogrammed the E4OD tranny.

[BigToe]

SoCalDesertRider wrote:
I loved the truck and would still be driving it today, had it not burned down in a fire, a year ago today. It served me well for the 4 years that I got to use it.

Wondered what had happened to you. Do you know the cause of the fire? Did it start in/with the truck, or from an external source?

SoCalDesertRider wrote:
I often wished for 4.56 or 4.88 gears. The 4.10's were just not enough gearing. The 7.3 likes to run in the 2500-3000 rpm range when towing heavy. 4.10 gears, even with short 235 stock size tires, wasnt enough gearing to make it rev enough in 3rd to pull the hills. So, it was down in 2nd alot at 40 mph.

A great illustration of the impact that rear axle ratio gearing has on useable transmission gears on a grade. When 4th is too high, and 2nd is too low, 3rd would be just right. But if the rear gear is already too tall, then 3rd too, becomes unusable just like 4th, which reduces a 4 speed transmission down to just a two speed with only one practically useable gear.

SoCalDesertRider wrote:
My engine was all stock, 235 horsepower rating. The old body trucks dont have intercoolers like the Superduty body trucks have. Not sure how much that really makes a difference, since the '99-'02 7.3's didn't have much higher HP rating than the old body trucks had.

The intercooled 7.3L engines with manual transmissions and engine coolant temperature sensor inputs to the PCM had a 17% increase in horsepower rating, to 275HP stock, by 2001-2.

SoCalDesertRider wrote:
also had the turbo waste gate programmed to close when dethrottling, to use as a sort of exhaust brake.

How would closing the turbo "waste gate" when "dethrottling" serve as a "sort of exhaust brake"? Are you sure you don't mean the Exhaust Back Pressure Valve?

[SoCalDesertRid1]

I had a '97 F350 cab/chassis flatbed dually 4wd with the 7.3 Powerstroke and E4OD auto trans, 4.10 gears and 235 tires. I loved the truck and would still be driving it today, had it not burned down in a fire, a year ago today. It served me well for the 4 years that I got to use it.

I towed 20,000 lbs combined weight with that truck a few times in the mountains in southern California and Arizona. It was no picknick.

I often wished for 4.56 or 4.88 gears. The 4.10's were just not enough gearing. The 7.3 likes to run in the 2500-3000 rpm range when towing heavy. 4.10 gears, even with short 235 stock size tires, wasnt enough gearing to make it rev enough in 3rd to pull the hills. So, it was down in 2nd alot at 40 mph.

My engine was all stock, 235 horsepower rating. The old body trucks dont have intercoolers like the Superduty body trucks have. Not sure how much that really makes a difference, since the '99-'02 7.3's didn't have much higher HP rating than the old body trucks had.

I didn't have a power chip or any exhaust or intake mods. The truck was very heavy when not towing anything, weighed 13,000 lbs by itself. Since it was so heavy all the time, I left the engine stock, to keep its reliability.

I did have alot of transmission work done to the truck. E4OD's have no engine braking when going down hills. That's scary. I had the trans fully rebuilt and modified valve body, heavy duty torque converter and electronic programming, also had the turbo waste gate programmed to close when dethrottling, to use as a sort of exhaust brake. All this did help alot with descending hills when towing at 20,000 combined.

I think if you do alot of power modifications to the engine and build the tranny up right and also, most importantly, change the axle ratio to 4.56 or 4.88, you may be get reasonable performance from the truck with that heavy trailer. It will not be great, but should get you by.

I really do like the 7.3 Powerstroke engine era. Very simple engines that are very reliable and reasonably powerful, for their time.

I replaced my burnt down 7.3 F350 with another great International engine, in a much bigger truck. I now have an '01 International 4800 (33,000 GVWR) crew cab 4x4, with a true medium duty commercial diesel engine, the DT466E inline-6, with High Torque output rating (850 lb/ft @ 1400rpm, 250 hp).

I'm very happy with the truck and engine. It goes down the road every day at 20,000 lbs GVW and pulls more on trailer without breaking a sweat. The 5.38 axle gearing and 5 speed Allison MD3050 tranny help too. 🙂

The tranny acutally has 6 forward gears inside it, but is programmed to only use 5. The 6th double overdrive gear is electronically unavailable. Some day, I intend to have the Allison dealer reprogram the tranny so I can use 6th gear and comfortably cruise at 65 mph around 1800 rpm, instead of the 55 mph at 1800 rpm that I cruise at now.