Comparing 7.3 to 6.7 towing ability

[Jcamper]

Did some quick calcs yesterday because I was curious. So far impressed with the 7.3 ability towing when paired with the 10 speed.
First, to get everyone on the same page, some mental warmup. Given unlimited gearing and rpm range, horsepower is the only thing that matters. However, with real world limitations in both, compromises exist. Torque only has weight and distance components, it only tells you the ability to do work, not how quickly work can be done. Horsepower adds a time component, so that is what you need when you ask the question “how fast can it do work?”
I did some basic calcs based on two tremors doing 70mph. This assumes a load/grade which requires both trucks to shift down, and shows why the gas and diesel are pretty close in reality.
Diesel torque at rear wheels is in yellow, gas in green.

 

[oops]

Can you share your sheet/calcs?

 

[Loshad]

I need it explained more simply…

 

[oops]

I need it explained more simply…

View attachment 41687

Simple, but doesn’t pass the 4th grade physics test.

 

[Loshad]

Oh, well, I'll dig out my old aerodynamics textbooks and see what they say. IIRC there was some physics involved.

 

[oops]

Oh, well, I'll dig out my old aerodynamics textbooks and see what they say. IIRC there was some physics involved.

Look for the part about the cube of velocity.

 

[oops]

@Jcamper where'd you get the transmission gear ratios from? Are they the same for the Gas and the Diesel? I had thought the transmissions were slightly different for each. Anyone who can confirm?

 

[thevol]

Interesting chart and thanks for sharing. Obviously the na gas motor needs to turn much higher rpms to match the diesels torque, but it can rev much higher. The turbo in the diesel is pushing more air in the engine while the na gas has to increase rpms. It would be interesting to see a chart with a supercharged 7.3 vs turbo diesel 6.7.

 

[Modman]

I had thought the transmissions were slightly different for each

I think I have this info on my laptop... But I am not there right now. As I get older I write things down to help myself remember (or type in this case)!

 

[CalTremor2020]

View attachment 41686Did some quick calcs yesterday because I was curious. So far impressed with the 7.3 ability towing when paired with the 10 speed.
First, to get everyone on the same page, some mental warmup. Given unlimited gearing and rpm range, horsepower is the only thing that matters. However, with real world limitations in both, compromises exist. Torque only has weight and distance components, it only tells you the ability to do work, not how quickly work can be done. Horsepower adds a time component, so that is what you need when you ask the question “how fast can it do work?”
I did some basic calcs based on two tremors doing 70mph. This assumes a load/grade which requires both trucks to shift down, and shows why the gas and diesel are pretty close in reality.
Diesel torque at rear wheels is in yellow, gas in green.

Finally someone speaking my language . I can’t tell you how many times I made similar spreadsheets when researching trucks (mostly speed at peak torque/power by gear). The 7.3L is a great engine choice.

@Jcamper where'd you get the transmission gear ratios from? Are they the same for the Gas and the Diesel? I had thought the transmissions were slightly different for each. Anyone who can confirm?

The Ford spec sheet says the ratios are the same. I’m reasonably certain (code for talking out my butt ) the transmissions are rated for the same torque throughput (1400Nm) but the torque converter is smaller on the 7.3L meaning it’s a different part number for the smaller bell housing. Maybe one of our technician members can confirm?

https://media.ford.com/content/dam/fordmedia/North%20America/US/product/2020/f-series-super-duty/2020-Super-Duty-Tech-Specs.pdf

 

[richtor]

The biggest issue is gas mpg while towing. Bottom line the 7.3 will tow the 6.7 will get better mileage.

 

[PapaRaptor]

Having both 7.3 and 6.7, The 7.3 will get it done. It struggles compared to the 6.7 and more shifting. Now compare the 7.3 to other brands especially gas V-8s and it will put them to shame.

 

[Cococounty]

Having both 7.3 and 6.7, The 7.3 will get it done. It struggles compared to the 6.7 and more shifting. Now compare the 7.3 to other brands especially gas V-8s and it will put them to shame.

Yup two totally different animals but people still keep saying they’re the same

 

[PapaRaptor]

Yup two totally different animals but people still keep saying they’re the same

If you like to go to the gas station more the 7.3 is the way to go. I just love the sound of it. I'm just burning the cheap 87 and it has not missed one beat. Love that new V-8 beast.

 

[Cococounty]

If you like to go to the gas station more the 7.3 is the way to go. I just love the sound of it. I'm just burning the cheap 87 and it has not missed one beat. Love that new V-8 beast.

Yeah I wouldn’t mind having one of each love the sound of gas big blocks

 

[PapaRaptor]

Yeah I wouldn’t mind having one of each love the sound of gas big blocks

Plus when you stop at the "Quick Stop" for your daily gas trip, you can get a dunker or ham sandwich right off the shelf. Thats living.

 

[JDBoss]

All I can say is that our 6.7 RARELY needs to downshift on hills/mountains with a truck camper in the bed and flat towing our JLUR (~6k lbs). Made three trips to the west coast this year in this configuration and while I can't make a direct comparison, our previous rig (2500 Ram 6.4 Hemi 4.10 gears with a truck camper and towing similar weight) would be downshifting NON-STOP in the mountains. For us, the 6.7 was $$ well spent, and it is unlikely I'd ever go back to gas. That's just our conclusion. Your mileage may vary - LOL

 

[Cococounty]

All I can say is that our 6.7 RARELY needs to downshift on hills/mountains with a truck camper in the bed and flat towing our JLUR (~6k lbs). Made three trips to the west coast this year in this configuration and while I can't make a direct comparison, our previous rig (2500 Ram 6.4 Hemi 4.10 gears with a truck camper and towing similar weight) would be downshifting NON-STOP in the mountains. For us, the 6.7 was $$ well spent, and it is unlikely I'd ever go back to gas. That's just our conclusion. Your mileage may vary - LOL

Towing in The mountains with an exhaust brake is nice to love mine use it all the time

 

[oops]

Don't we have enough belief based diesel-vs-gas debate threads here? OP is posting mathematic truths and y'all just want to talk about feelings.

 

[oops]

It would be interesting to see a chart with a supercharged 7.3 vs turbo diesel 6.7.