F450 vs Ram 3500 DRW tow vehicle

[___M4Lourenco]

So the wife and I are moving to the full time RV lifestyle. We just purchased a 42' toy hauler this weekend, with a GVWR of 20K#. Now I'm looking at a tow vehicles. I'm considering either purchasing a new 2020 Ford or Ram, but leaning more towards the Ram, after doing some homework and my own research. Before I make my final decisions I wanted to hear the RV community opinions between these trucks. I greatly appreciate your comments.

Thank you!

[4x4ord]

Here is a Link but looking at the bsfc graph that Shiner posted shows the same sort of thing.

[me2]

4x4ord wrote:


Tests have been conducted on Agricultural tractors by Nebraska Tractor Tests and have shown that when 1/2 of rated HP is needed a tractor will burn nearly 30% less fuel running the engine at 80% rated engine rpm vs running at full rated rpm.

Interesting. Do you have a link for this ?

[me2]

jdc1 wrote:
CVRA and ACTM stickers will probably be mandatory on the F450, as will stopping at scales in California.

Does the OP live in California ? If he doesn't, why would he need a CVRA if his home state doesn't require it ?

"Excluded Vehicles—The following vehicles are excluded from the CVRA:

Pickup trucks continue to be registered by the unladen weight and assessed a weight fee regardless of the vehicle’s GVW. The unladen weight of a pickup cannot exceed 8,000 pounds and its GVW rating must be less than 11,500 pounds."

https://www.dmv.ca.gov/portal/handbook/vehicle-industry-registration-procedures-manual-2/commercial-vehicles/commercial-vehicle-registration-act-of-cvra/

"If you’re headed down the highway with your RV in tow, you may see a weigh station and wonder if you are required to stop. The short answer to this is no, you do not have to stop at a weigh station."

https://www.gillettesinterstaterv.com/rv-weights-and-weigh-stations/

[NRALIFR]

Cummins12V98 wrote:

Grit dog wrote:
So Ram 3500 or Ford 450??
Lol

I forgot what we were talking aboot. Thanks!

I didn’t. I was just waiting for them to get out of the weeds.

Another fo’fitty for me, with a scoop of 7.3 Godzilla on top. :B

:):)

[Cummins12V98]

Grit dog wrote:
So Ram 3500 or Ford 450??
Lol

I forgot what we were talking aboot. Thanks!

[4x4ord]

Shiner... Back to the better mileage running higher rpm .... what were you getting for mileage in sixth and how much improvement do you think you got revving your engine higher?

[4x4ord]

I think we agree on a lot more than we would disagree. You were saying that a smaller bore vs stroke lends itself to torque at a lower rpm. I don't see any reason for that.

[ShinerBock]

I will give you an example. Back when I was looking for a fixed geometry turbo, I could have went with an S369 turbo whis is a huge turbos and would have moved my peak torque points further down the rpms range which I did not want for towing. I could have gone with an S361 which would have would have made boost sooner than stock pushing my peaks to lower rpms, but would have little top end power. I ended up going with an S364.5 which is the middle choice between these two which makes peak torque at a little more rpms than stock but with more top end.

All without changing my fuel maps so the amount of power being generated, efficiency, and when would have changed with each turbo by adding/decreasing air even without altering fuel. Why, because the engine just injected fuel and the each of these turbos efficiency maps dictated how much air it can utilize at each rpm. You cannot do this with a gas engine because you would have to adjust the amount of fuel for the amount of air being added.

Each one of these turbos would have not only changed the rpm when I made peak power but also the efficiency at each rpm. With electronically controlled VG turbos, you have more control and can adjust the vanes to make peak power at various rpms, however, you also have to keep emissions and drive pressures in check.

[ShinerBock]

4x4ord wrote:
^^^^ Your right.... more fuel more torque. In order to burn fuel you need air. Read my post and think about it until you understand it. I'm not sure where you are actually disagreeing with me now?

But that is just it. You are assuming that these engines can get the same amount of power out of X amount of fuel. That is not the case and it is dependent on a lot of factors especially when emissions are involved that require you to stay below a certain NOx level. You can have two Cummins ISB engines sitting side by side with different turbos on them, and depending on the efficiency maps of the turbos will dictate how much power and efficiency each engine can achieve at X rpm. Same would be true if they had the same turbo, but different bore/stroke ratio or different cams.

[Grit_dog]

So Ram 3500 or Ford 450??
Lol

[4x4ord]

^^^^ Your right.... more fuel more torque. In order to burn fuel you need air. Read my post and think about it until you understand it. I'm not sure where you are actually disagreeing with me now?

[ShinerBock]

4x4ord wrote:
You can increase an engine's displacement/torque by increasing bore, stroke, or number of pistons. The Cummins and Powerstroke are both 6.7 liter engines so will have similar cylinder pressure when they are making 1000 lbft of torque. Stroke vs bore makes no difference. Torque is a function of the fuel burned per revolution. Increasing the boost or the bore or the stroke puts more air in the cylinder to allow for more fuel to be injected. If you can burn 10% more fuel per revolution you should see about 10% more torque.

You are describing a gas engine here, not a diesel. A diesel is regulated by fuel, not air. In order to increase boost in a diesel, you have to increase fuel. A diesel basically adds fuel and utilizes what ever air is available which is why turbos generally make diesels more efficient since it adds more air that what it can naturally take in. You can "artificially" alter the peak with fuel and boost control with a VG turbo.

Also, a bore/stroke ratio, along with the cam, does play a huge role in an engines efficiency and when it is most efficient.

We are at another disagreement. On the last disagreement, you said that you highly doubt that my truck gets better fuel economy pulling mt RV in 5th than 6th because you never seen a BSFC showing that. I proved that it does get better fuel economy with a BSFC map. So prove me wrong. Show me a BSFC of the 6.7L Powerstroke. If you can't, then it is all subjective.

[4x4ord]

Back when engines used mechanical injection pumps and injectors graphing an engine's torque curve correlated exactly with its BSFC at maximum load. Peak torque represented the point at which the engine was getting the most work out of a squirt of fuel.

[4x4ord]

You can increase an engine's displacement/torque by increasing bore, stroke, or number of pistons. The Cummins and Powerstroke are both 6.7 liter engines so will have similar cylinder pressure when they are making 1000 lbft of torque. Stroke vs bore makes no difference. Torque is a function of the fuel burned per revolution. Increasing the boost or the bore or the stroke puts more air in the cylinder to allow for more fuel to be injected. If you can burn 10% more fuel per revolution you should see about 10% more torque.