I'm currently towing my KZ Montego Bay Sportster with a 14K dry weight and close to 20K fully loaded with a 1999 F550 7.3 with 4.88 rear end. I'll start by saying I love this truck. In most all situations it is a great tow vehicle. Where it begins working hard is when it is climbing 6 to 7% grades. I try to keep EGT under 1300 degrees. This equals speeds of 35MPH with RPMs of 2200 to 2500.So I am considering going to a used Supercrewzer or western hauler type tow vehicle. These are available with Cat 300 to 330 HP diesels and 6 speed Allison transmissions. My question is to owners of this type vehicle. Is there an advantage in going to the F650? Would be interested in your real world results. Performance as in MPG, Climbing ability, comfort level.Keeping in mind this will not be a daily driver but used mostly as a tow vehicle.Thanks in advance for your input.Mike

You can find the f650 with Cat and Cummins engines. Your issue is not enoug gears in the transmission.Any modern diesel with 6spd trans will pull that trailer 3 times better.

This isn't first hand experience, but a buddy of mine went from a 7.3 F350 to an F650. I'm not sure which engine he has but is likely has 300 or so hp. He says it handles like a dream but doesn't climb hills any faster than his old truck. Not sure how much you want to spend, but a newer diesel dually pickup will perform much better on hills than your current truck.

I don't think you'll enjoy the ride.

The F650 may be too hard riding unless you go with an air ride suspension because the pin weight will not deflect the suspension enough. Even with 4000+ lbs on my 5500, it is still a stiff ride (it will be going up to 6000 lbs shortly).Although your 7.3 PSD was a good engine, it doesn't have the horsepower of the generations of engines that followed it nor does it have the range of gearing. I suggest looking at the current class 5 chassis cabs from Ford and Ram before looking to go to a bigger class truck. You will be able to run 4.30 or 4.44 gearing in this selection of trucks which also make highway cruising much more comfortable than the current RPM's you have to now turn.

Here, let me save you about 70 grand.#1. Stop worrying about 1,300 EGT. With piston squirter you can go well above 1,500 EGT.#2. Tune that 7.3 up to give it more fuel and timing. #3. Put a big wheel turbo on that thing to keep the EGT's down with more fuel timing.#4. That truck was built for a commercial rating not to haul a small RV around. You have a lot of HP margin to play with.#5. Go on vacation!

F650 as 5th wheel tow vehicle. | Good Sam Community

Wild_Card
Explorer
Mar 21, 2017
Understand your points OP, I would rather have the 650 with a Cummins though over the Kitty Cat. More aftermarket support.

Look for Freightliner bussiness class M2 as well. I belive they can be had with a 60 series detroit, another good engine to have.
lightning_drive
Explorer
Mar 20, 2017
Wild Card wrote:
Turtle n Peeps wrote:
Here, let me save you about 70 grand.

#1. Stop worrying about 1,300 EGT. With piston squirter you can go well above 1,500 EGT.

#2. Tune that 7.3 up to give it more fuel and timing.

#3. Put a big wheel turbo on that thing to keep the EGT's down with more fuel timing.

#4. That truck was built for a commercial rating not to haul a small RV around. You have a lot of HP margin to play with.

#5. Go on vacation!

I agree. Intake, exhaust and a good tuner. Should be able to get 400crank hp easily 500 wiTH injectors. The Pistons in that vintage PSD are forged, built to handle a good power boost.

I'm more of a stock kinda guy. Was thinking of the cat at 300 or 330 HP and 800 to 900 ft lbs of torque.

I never thought of a 20K lb toy hauler as a small RV :{) The 99 F550 has a max tow rating of 26K.
As to #5 I'm on it retired in Jan.
lightning_drive
Explorer
Mar 20, 2017
Wild Card wrote:
You can find the f650 with Cat and Cummins engines. Your issue is not enoug gears in the transmission.

Any modern diesel with 6spd trans will pull that trailer 3 times better.

Agreed Just too much green to get in that game.
lightning_drive
Explorer
Mar 20, 2017
Wild Card wrote:
You can find the f650 with Cat and Cummins engines. Your issue is not enoug gears in the transmission.

Any modern diesel with 6spd trans will pull that trailer 3 times better.

No argument there just can't to spend the $75 to $80 grand for the new 6.7. Just retired so don't want to take on a bunch of debt. Not a fan of car payments.
I've been seeing the western Haulers and ford Supercrewzers with asking prices $36 to $39K 2001 to 2006 with cat/Allison combo. 99 to 150K on the clock.
Sell my F550 for $10K and my 76 Bronco with explorer MPI 5.0 for $17K and I'm not coming out of pocket too much for the F650.
Wild_Card
Explorer
Mar 20, 2017
Turtle n Peeps wrote:
Here, let me save you about 70 grand.

#1. Stop worrying about 1,300 EGT. With piston squirter you can go well above 1,500 EGT.

#2. Tune that 7.3 up to give it more fuel and timing.

#3. Put a big wheel turbo on that thing to keep the EGT's down with more fuel timing.

#4. That truck was built for a commercial rating not to haul a small RV around. You have a lot of HP margin to play with.

#5. Go on vacation!

I agree. Intake, exhaust and a good tuner. Should be able to get 400crank hp easily 500 wiTH injectors. The Pistons in that vintage PSD are forged, built to handle a good power boost.
Turtle_n_Peeps
Explorer
Mar 20, 2017
Here, let me save you about 70 grand.

#1. Stop worrying about 1,300 EGT. With piston squirter you can go well above 1,500 EGT.

#2. Tune that 7.3 up to give it more fuel and timing.

#3. Put a big wheel turbo on that thing to keep the EGT's down with more fuel timing.

#4. That truck was built for a commercial rating not to haul a small RV around. You have a lot of HP margin to play with.

#5. Go on vacation!
Bedlam
Moderator
Mar 20, 2017
The F650 may be too hard riding unless you go with an air ride suspension because the pin weight will not deflect the suspension enough. Even with 4000+ lbs on my 5500, it is still a stiff ride (it will be going up to 6000 lbs shortly).

Although your 7.3 PSD was a good engine, it doesn't have the horsepower of the generations of engines that followed it nor does it have the range of gearing. I suggest looking at the current class 5 chassis cabs from Ford and Ram before looking to go to a bigger class truck. You will be able to run 4.30 or 4.44 gearing in this selection of trucks which also make highway cruising much more comfortable than the current RPM's you have to now turn.
2oldman
Explorer II
Mar 20, 2017
I don't think you'll enjoy the ride.
rjstractor
Nomad
Mar 20, 2017
This isn't first hand experience, but a buddy of mine went from a 7.3 F350 to an F650. I'm not sure which engine he has but is likely has 300 or so hp. He says it handles like a dream but doesn't climb hills any faster than his old truck. Not sure how much you want to spend, but a newer diesel dually pickup will perform much better on hills than your current truck.
Wild_Card
Explorer
Mar 20, 2017
You can find the f650 with Cat and Cummins engines. Your issue is not enoug gears in the transmission.

Any modern diesel with 6spd trans will pull that trailer 3 times better.

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F650 as 5th wheel tow vehicle.

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