Towing Limits of 7.3 Powerstroke

[adamis]

As my wife and I look at making the transition from a Truck Camper to a 5th wheel, the question about the suitability of our truck for the job comes into question. Someday a new truck with all the bells and whistles (and the quietness) might be on the table but not immediately.

My current truck is an early 1999 F350 Dually Quad Cab Long Bed 2WD. I've pulled my fully loaded 5k lb Truck Camper plus ~3k lb cargo trailer without any issues. I bought the truck off a guy who used it to haul his drag race car around in a 32ft goose neck trailer. I think he liked to work on the truck almost as much as the race car. Lots of "extras" all over the place. On a recent 3000 mile road trip I had a fuel injector go bad so I took the opportunity to dump about $8k into the engine, to include bigger injectors, bigger turbo, new up pipes, new HPOP and Hydra Tuner. The tranny has the 6.0 oil cooler mod and a Banks Torque Converter and Shift computer installed. Stock the truck made ~20lbs of boost, I'm now pushing 30lbs+ and haven't really tested the limits yet (nor do I plan to). My mechanic (who used to drag race 7.3s) guesstimated the HP to be in the realm of ~400 to 450hp. I am not going to dyno it but seat of the pants dyno I don't doubt it is far off from his guestimate.

Getting back to the towing part... I know the towing limit of my truck is right around the 13k lb range. I'm looking in trailers that are in the 12k to 13k range (and expect about another 1k lb in weight once packed. Pin weight for trailers in this range looks to be in the 2500lb range which is half of what my camper weighs when loaded so I think I'm not concerned about that.

My question really isn't about whether I will have the power to tow it (or the legality of it) but rather the handling / braking aspect. I already have a brake controller but might update it to something more modern. I'm thinking about specing the trailer with disc brakes to give more stopping power.

Does anyone else have experience towing heavy trailers with the 7.3 and if so, do you have an recommendations on what to do or not to do as far as mods and upgrades?

[cannesdo]

I lived in and towed 16k lbs -- a 36' Alpenlite -- for 10 years with my 2001 Ford F250 7.3L. Yes, some people are going to freak out about this but maybe it will put your mind at ease about towing 14 or 15k lbs. It had air bag support in the truck but no other special modifications. I later upgraded the transmission cooler. I had to keep an eye on the engine/transmission temps while towing in the mountains. It's a tough truck but pretty weak pushing loads in reverse. I once had to push my rig uphill into a narrow space at a private house down in Escondido, CA and could only do it if I got a run at it and steered like my life depended on it. It would just stop part way up. But towing forward -- it's a champ. I always felt safe. I guess if I changed anything I would have gotten the transmission cooler upgrade sooner. Regular brakes on the trailer felt like more than enough. Just down-shift on long downward grades and take your time.

Actually, I did have an Edge chip on it most of that time which probably helped.

[adamis]

EGTs are definitely the limiting factor in getting solid performance out of the 7.3. Before I put in the new Turbo, (but with lots of other mods) the Truck had more than enough power for my needs but the limiting factor was the EGTs. I often found myself doing 45mph pulling up a grade watching to keep EGTs under 1200 with my foot only at half throttle. The power was there to be had but at the expense of possible damage because of the temps.

The latest round of mods and in particular, the upgrade to the KC turbo changed all of that. Going from 20lbs of boost to 30+ lbs of boost is obviously a huge help in getting the air moved through the engine and keeping it cool. I still keep an eye on the EGT gauge but in general the EGTs have dropped by at least 200 deg if not 300+ for the same pull up a long grade. The throttle response is also fantastic as well. I still have two upgrades in the plans, changing to a newer radiator and intercooler from Mishimoto and upgrading my already upgraded 3" exhaust to a 4".

The difference in what the newer turbos can do (along with other mods) is like night and day for the 7.3. Unloaded this 8000lb truck is surprisingly fast, maybe not going to take on a sports car fast but faster than any other car I have in my garage. That being said, the writing is on the walls that the truck will someday be replaced (not sold, you will have to pry my 7.3 off my cold dead fingers...). I think once we start doing some longer trips, the noise and lack of creature comforts will drive us to look at a newer truck.

All that being said, my goal isn't to pull up a 6% grade at 70mph. I agree with others that slow and steady both up and down is the right approach. If I can maintain 55mph (or worst case minimum 45mph) I'm pretty happy. It isn't that I necessarily mind going slower if I had to but at some point you become a hazard to others as they aren't expecting a slow vehicle and can end up on your bumper.

[cummins2014]

4x4ord wrote:

cummins2014 wrote:

4x4ord wrote:
Your upgrades .... exhaust brake, turbo, additional power and transmission, plus the fact that you've got a dually should allow you to very easily handle a 13k 5ver. I would consider a 13k 5ver a light trailer. If you have a gear that will put your engine at an rpm where it makes 400 HP @ 55 mph you will be able to maintain that 55 mph up a 7% grade towing 13k lbs.

I agree ,but if you have dealt much towing fairly heavy with a 7.3 the ETG's are the limiting factor. I dealt with it nearly the whole time I owned that truck ,nearly 16 years . A stock 7.3 just doesn't have it for a heavier fifth wheel , unless you do some mods. I did a few ,and it did help, but the ETG's were the limiting factor, as said it had it there ,but the ETG's would climb up over 1200 degrees ,and I had to get out of the throttle.

Back when the 7.3 was very popular ,and new, ETG's were always a subject on the forums . Water injection, bigger intercoolers etc to deal with it.

I know very little about the 7.3 diesel and you're absolutely right that EGTs are often the limiting factor pulling grades. Even though the OP has upgraded his turbo, he may or may not be gaining a whole lot as far a EGTs are concerned, because he is also adding fuel .... he's going to need to be watching his pyrometer. I would think 1200* is a very safe level to run the EGT to, so ong as it is being measured pre turbo. I ran my Duramax to 1400 at times and as far as I know it never hurt anything.

I would let it run up over 1200, If I remember 1280 was the magic number. No idea what the EGT's will run with the OP's 7.3 , but suspect before he reaches that threshold he can run a bit harder then I was able to. As said the throttle was there ,but the temperatures wouldn't let me .

Those days are over, I don't miss that part . Now its just let the truck pull the grade with a bit more ease. IMO a much more enjoyable drive, then having to watch gauges on transmission , ETG's etc. Pushing a truck that didn't really have it in it .

[4x4ord]

cummins2014 wrote:

4x4ord wrote:
Your upgrades .... exhaust brake, turbo, additional power and transmission, plus the fact that you've got a dually should allow you to very easily handle a 13k 5ver. I would consider a 13k 5ver a light trailer. If you have a gear that will put your engine at an rpm where it makes 400 HP @ 55 mph you will be able to maintain that 55 mph up a 7% grade towing 13k lbs.

I agree ,but if you have dealt much towing fairly heavy with a 7.3 the ETG's are the limiting factor. I dealt with it nearly the whole time I owned that truck ,nearly 16 years . A stock 7.3 just doesn't have it for a heavier fifth wheel , unless you do some mods. I did a few ,and it did help, but the ETG's were the limiting factor, as said it had it there ,but the ETG's would climb up over 1200 degrees ,and I had to get out of the throttle.

Back when the 7.3 was very popular ,and new, ETG's were always a subject on the forums . Water injection, bigger intercoolers etc to deal with it.

I know very little about the 7.3 diesel and you're absolutely right that EGTs are often the limiting factor pulling grades. Even though the OP has upgraded his turbo, he may or may not be gaining a whole lot as far a EGTs are concerned, because he is also adding fuel .... he's going to need to be watching his pyrometer. I would think 1200* is a very safe level to run the EGT to, so ong as it is being measured pre turbo. I ran my Duramax to 1400 at times and as far as I know it never hurt anything.

[cummins2014]

Wadcutter wrote:

cummins2014 wrote:

As said I towed nearly 16 years with the the early 99 Superduty 7.3 350 short bed. I wouldn't say I had a problem towing in the rockies considering I live here in the west. The most I towed was just over 13K , 38' fifth wheel. Have talked to many many people towing with a 7.3 over the years. Just curious occasionally I hear comments similar to yours , never had a problem, as said neither did I , but hopefully you were are a grade with a passing lane or you were holding up traffic 🙂

Driving on grade with the 7.3 and 5er is no different than any other vehicle. You adapt to the vehicle and conditions. As you know there are a bunch of semis that creep up the grades. Too many drivers think because the speed limit is 70 mph that they need to keep going 70 mph up a 6+% grade. Then wonder why at the top of the pass their temp gauge is well into the red and others are sitting there with their hoods up and water on the ground.
Same with going down the grade. Just because the speed limit is 70 mph doesn't mean you have to run 70 mph downhill and ride the brakes. But we've all seen too many pulling trailers who do it. Not only seen them but smelled them when they went by.
It's not rocket science. It's knowing how to adapt to the conditions and vehicle. Doesn't matter if the vehicle has a 7.3 or a Detroit diesel or a 1.6L gas.

Thanks for the explanation, but yes I did adapt. Did you not see the smiley face. I knew what I had ,and 70 downhill or uphill was NOT something I wanted to do. I don't do it now, and I have the power to do so.

Lets put it this way its nice to be able run 60-65 on some of the long grades instead of 30-35, plus set the cruise for a long downhill grade at a safe speed ,and let the truck do its thing with exhaust brake ,and never have to touch the brakes . I have adapted well to that also .

The 7.3 was great in its day. I don't miss the noise ,the smell, the lack of power ,and no exhaust brake . Other then that ,yes its a great truck 🙂

[Wadcutter]

cummins2014 wrote:

As said I towed nearly 16 years with the the early 99 Superduty 7.3 350 short bed. I wouldn't say I had a problem towing in the rockies considering I live here in the west. The most I towed was just over 13K , 38' fifth wheel. Have talked to many many people towing with a 7.3 over the years. Just curious occasionally I hear comments similar to yours , never had a problem, as said neither did I , but hopefully you were are a grade with a passing lane or you were holding up traffic 🙂

Driving on grade with the 7.3 and 5er is no different than any other vehicle. You adapt to the vehicle and conditions. As you know there are a bunch of semis that creep up the grades. Too many drivers think because the speed limit is 70 mph that they need to keep going 70 mph up a 6+% grade. Then wonder why at the top of the pass their temp gauge is well into the red and others are sitting there with their hoods up and water on the ground.
Same with going down the grade. Just because the speed limit is 70 mph doesn't mean you have to run 70 mph downhill and ride the brakes. But we've all seen too many pulling trailers who do it. Not only seen them but smelled them when they went by.
It's not rocket science. It's knowing how to adapt to the conditions and vehicle. Doesn't matter if the vehicle has a 7.3 or a Detroit diesel or a 1.6L gas.

[cummins2014]

TXiceman wrote:
We had a 2002, 7.3L dually that we used to tow pretty much at rated limits. The truck had a SuperChips Micro Tuner and gauges for Pyro, boost and tranny temp. The tranny is a weak point in those trucks. I installed an upgraded torque converter, large stacked plate oil cooler and ran synthetic tranny oil. The truck did a great job, but I had to keep an eye on the pyro when pulling grades and back out of it at times.

Keep an eye on the tranny temp and pyro and roll on. The exhaust brake would be great.

Ken

Once I went to the 6.0 tranny cooler my overheating problems with that 4R100 were over . I too went with a Superchip for awhile ,then to the DP tuner ,much better tuner .

[cummins2014]

StirCrazy wrote:

adamis wrote:
As my wife and I look at making the transition from a Truck Camper to a 5th wheel, the question about the suitability of our truck for the job comes into question. Someday a new truck with all the bells and whistles (and the quietness) might be on the table but not immediately.

My current truck is an early 1999 F350 Dually Quad Cab Long Bed 2WD. I've pulled my fully loaded 5k lb Truck Camper plus ~3k lb cargo trailer without any issues. I bought the truck off a guy who used it to haul his drag race car around in a 32ft goose neck trailer. I think he liked to work on the truck almost as much as the race car. Lots of "extras" all over the place. On a recent 3000 mile road trip I had a fuel injector go bad so I took the opportunity to dump about $8k into the engine, to include bigger injectors, bigger turbo, new up pipes, new HPOP and Hydra Tuner. The tranny has the 6.0 oil cooler mod and a Banks Torque Converter and Shift computer installed. Stock the truck made ~20lbs of boost, I'm now pushing 30lbs+ and haven't really tested the limits yet (nor do I plan to). My mechanic (who used to drag race 7.3s) guesstimated the HP to be in the realm of ~400 to 450hp. I am not going to dyno it but seat of the pants dyno I don't doubt it is far off from his guestimate.

Getting back to the towing part... I know the towing limit of my truck is right around the 13k lb range. I'm looking in trailers that are in the 12k to 13k range (and expect about another 1k lb in weight once packed. Pin weight for trailers in this range looks to be in the 2500lb range which is half of what my camper weighs when loaded so I think I'm not concerned about that.

My question really isn't about whether I will have the power to tow it (or the legality of it) but rather the handling / braking aspect. I already have a brake controller but might update it to something more modern. I'm thinking about specing the trailer with disc brakes to give more stopping power.

Does anyone else have experience towing heavy trailers with the 7.3 and if so, do you have an recommendations on what to do or not to do as far as mods and upgrades?

I had a early 99 7.3 that I had up around 450 hp and 935Ft-lbs. mine was a 3/4 tone, automatic, 2WD, shortbox super cab. when I bought my 5th wheel (39.5feet long and 14-16K lbs) I did a couple trips with it and it towed it just fine and got very good milage. The only reason I bought the 2014 was that with the 5th wheel on and no passengers I was already 300lbs over my max for the rear axel. If I would have had a 1 ton I would probaby still have it.

I never had any egt issues, just gear down out of overdrive and keep the reves up and slow down a little andit was fine. going up a grade 8-11 hill I was able to maintain 55 to 60 mph, and the pour man exhaust brake(EBP control valve control kid) was able to hold it pretty deicent going down a grade 6 hill.

I a seeing a lot of coments about drum brakes, My early 99 came with 4 wheel disk ABS all around , thought they all did...

having said that, even though I had the 7.3 hopped up so much my 2014 with 400/800 out towes it hands down in the low and midrange rpms and is a much more plesent truck due to the smoothness and quietness. The 6.7 is the first motor that I would consider better than the 7.3

Steve

The disc brake comments are for the fifth wheel , not the truck. My early 99 had four wheel anti lock disc brakes .

Same here , I am down playing the 7.3 ,its a great motor, but no where near what my 6.7 Cummins will do towing the same weight , no comparison .

[TXiceman]

We had a 2002, 7.3L dually that we used to tow pretty much at rated limits. The truck had a SuperChips Micro Tuner and gauges for Pyro, boost and tranny temp. The tranny is a weak point in those trucks. I installed an upgraded torque converter, large stacked plate oil cooler and ran synthetic tranny oil. The truck did a great job, but I had to keep an eye on the pyro when pulling grades and back out of it at times.

Keep an eye on the tranny temp and pyro and roll on. The exhaust brake would be great.

Ken

[StirCrazy]

adamis wrote:
As my wife and I look at making the transition from a Truck Camper to a 5th wheel, the question about the suitability of our truck for the job comes into question. Someday a new truck with all the bells and whistles (and the quietness) might be on the table but not immediately.

My current truck is an early 1999 F350 Dually Quad Cab Long Bed 2WD. I've pulled my fully loaded 5k lb Truck Camper plus ~3k lb cargo trailer without any issues. I bought the truck off a guy who used it to haul his drag race car around in a 32ft goose neck trailer. I think he liked to work on the truck almost as much as the race car. Lots of "extras" all over the place. On a recent 3000 mile road trip I had a fuel injector go bad so I took the opportunity to dump about $8k into the engine, to include bigger injectors, bigger turbo, new up pipes, new HPOP and Hydra Tuner. The tranny has the 6.0 oil cooler mod and a Banks Torque Converter and Shift computer installed. Stock the truck made ~20lbs of boost, I'm now pushing 30lbs+ and haven't really tested the limits yet (nor do I plan to). My mechanic (who used to drag race 7.3s) guesstimated the HP to be in the realm of ~400 to 450hp. I am not going to dyno it but seat of the pants dyno I don't doubt it is far off from his guestimate.

Getting back to the towing part... I know the towing limit of my truck is right around the 13k lb range. I'm looking in trailers that are in the 12k to 13k range (and expect about another 1k lb in weight once packed. Pin weight for trailers in this range looks to be in the 2500lb range which is half of what my camper weighs when loaded so I think I'm not concerned about that.

My question really isn't about whether I will have the power to tow it (or the legality of it) but rather the handling / braking aspect. I already have a brake controller but might update it to something more modern. I'm thinking about specing the trailer with disc brakes to give more stopping power.

Does anyone else have experience towing heavy trailers with the 7.3 and if so, do you have an recommendations on what to do or not to do as far as mods and upgrades?

I had a early 99 7.3 that I had up around 450 hp and 935Ft-lbs. mine was a 3/4 tone, automatic, 2WD, shortbox super cab. when I bought my 5th wheel (39.5feet long and 14-16K lbs) I did a couple trips with it and it towed it just fine and got very good milage. The only reason I bought the 2014 was that with the 5th wheel on and no passengers I was already 300lbs over my max for the rear axel. If I would have had a 1 ton I would probaby still have it.

I never had any egt issues, just gear down out of overdrive and keep the reves up and slow down a little andit was fine. going up a grade 8-11 hill I was able to maintain 55 to 60 mph, and the pour man exhaust brake(EBP control valve control kid) was able to hold it pretty deicent going down a grade 6 hill.

I a seeing a lot of coments about drum brakes, My early 99 came with 4 wheel disk ABS all around , thought they all did...

having said that, even though I had the 7.3 hopped up so much my 2014 with 400/800 out towes it hands down in the low and midrange rpms and is a much more plesent truck due to the smoothness and quietness. The 6.7 is the first motor that I would consider better than the 7.3

Steve

[cummins2014]

ford truck guy wrote:
I went from drum 12 x 2 to drum 12-1/4 x 3-3/8 to disc... I too will NEVER go back to drum brakes...

Not sure anyone will believe how much better they are then drum brakes, just have to tow a fifth wheel with disc to know .

[ford_truck_guy]

I went from drum 12 x 2 to drum 12-1/4 x 3-3/8 to disc... I too will NEVER go back to drum brakes...

[cummins2014]

Wadcutter wrote:
I had a 99.5 F-350 SRW, crew cab, 4X4, 8 ft bed with the 7.3. I didn't have near the upgrades you've done. I ran a small programmer which gave me a little boost in HP and torque. I did the programmer mainly to get better shifting as it tweaked the shift points. I did not have an exhaust brake.
The last 5er I pulled was a 40 ft which loaded maxed at 14,500. Never had a problem pulling. Made numerous trips thru the Rockies. Pulled some pretty good hills and never had a problem. Even with SRW it was very stable in any wind direction. Without the exhaust brake I had watch downhill runs but that would have been the case with any truck. I never had the 6.0 cooler. All stock except for the low grade programmer.
The 7.3 was a good engine. A local truck mechanic friend kept trying to get me to really hot rod it saying it was near bullet proof and could really be turned up. It did all I needed without hot rodding it.

As said I towed nearly 16 years with the the early 99 Superduty 7.3 350 short bed. I wouldn't say I had a problem towing in the rockies considering I live here in the west. The most I towed was just over 13K , 38' fifth wheel. Have talked to many many people towing with a 7.3 over the years. Just curious occasionally I hear comments similar to yours , never had a problem, as said neither did I , but hopefully you were are a grade with a passing lane or you were holding up traffic 🙂

[cummins2014]

adamis wrote:
Thanks, that is exactly the type of info I was looking for. Yes, I do have the Banks Exhaust brake already and use it all the time with the current setup. It has been a fantastic tool in the toolbox for handling the mountains.

EGTs since the Turbo Upgrade have been very good. Truck hardly breaks a sweat pulling the 9000lbs of Camper and Trailer now. I do believe the 5th wheel will test it more but like you, before the upgrades I've done the 35mph in second gear without much issue. Maybe I will be able to maintain 45 or 55mph with what I have now which would be just fine.

If the disc brakes are that much of a difference, I will make that a priority. Stopping that much inertia is really my largest concern for sure.

As far as disc brakes , I will never tow a fifth wheel without them ,now that I have . They are definitely that much of a difference. I don't think anyone would disagree if they have went from drum brakes on a fifth wheel which is standard , and upgraded to disc.

I was for awhile going to do injectors, turbo , bigger intercooler etc, but as said after 16 years it was time for a change. But that 7.3 was fantastic for what it was .