Gas verses Diesel Tow Vehicle

[ROBERT CROSS]

Don't really worry about hp/tq...we tow in the 'comfort zone" In our case 21-2200rpm, the engine/mpg sweet spot 63-65 mph. 👍
Gas, diesel... whatever you choose is best. 🤔

Bob
🇺🇸

[DewTheDew]

Originally Posted by gypsydad

I think he's (Slowmover) a troll...not sure why he is so fixated in insulting folks with his jiberish? Could be wrong...been wrong before...once!

They are mostly the same so perhaps we could just put a sticky post of his at the top so he doesn't have to keep typing it.

[SCOTTinNJ]

HP = Torque x RPM ÷ 5252

You can make HP by having high torque, high RPM, or both.

High torque at low RPM sure feels more powerful and less frantic than lower torque and high RPM (for equal HP ratings), but both will get equal work done.

[pteck]

Originally Posted by Tuco

I have to admit this post really pissed me off (as it was intended I'm sure). I was up half the night wracking my brain as to why Torque trumps HP in a hill climb and Diesel is better than gas or electric. Real world use cases told my senses that I was right, but for the life of me I couldn't get to the right math to solve the issue. I changed the way I was searching the internet this morning and finally found the answer! I couldn't have picked a better video to showcase the point either. HP shined in the drag race, but with the same weight, rear gear and transmission gear (rpm) similar torque produced similar time to the top of the grade. Now I think i'll let you two engineers figure it out on your own. I'm more than satisfied with the knowledge I gained on my own despite your incorrect information. We can continue this conversation once you have learned the error of your ways! Until then know i'll be laughing every time you post about how great HP is in towing!

Dave

Dave. I apologize that I offended you. I sincerely did not post this in malice.

If I were completely off base in an area outside of my expertise, I would hope a friend would clue me in.

My only intent is that concepts are factually correct when comparing engines. An area that I have spent quite a bit of time in. Developing diesel variants no less.

I'm hearing that my ways could use some more tact. Thanks for that.

[Tuco]

Originally Posted by pteck

Dave. I apologize that I offended you. I sincerely did not post this in malice.

If I were completely off base in an area outside of my expertise, I would hope a friend would clue me in.

My only intent is that concepts are factually correct when comparing engines. An area that I have spent quite a bit of time in. Developing diesel variants no less.

I'm hearing that my ways could use some more tact. Thanks for that.

Actually I have to thank you for getting me angry. It got me to take that final step back and see the big picture. Holding the answer back is wrong on my part, but handing it out doesn't help you either (something about giving a man a fish...). So lets look at a simple scenario using your favorite equation (tbh I like it too).

HP = Torque x RPM ÷ 5252

We have a vehicle sitting on flat ground and then moved to a 5% grade. Looking strictly at the drive wheels, what HP and Torque are required to hold that vehicle stationary? This is in general terms, i'm not looking for a real number here.

[Adventure.AS]

Originally Posted by Tuco

... So lets look at a simple scenario using your favorite equation (tbh I like it too).

HP = Torque x RPM ÷ 5252

Shouldn't that be HP = (Torque X RPM) ÷ 5252?

[Tuco]

Originally Posted by Adventure.AS

Shouldn't that be HP = (Torque X RPM) ÷ 5252?

Or

Torque X RPM
--------------- = HP
5252

[Kanusport]

I am a huge fan of the ecoboost f150. It has tons of power and torque. One thing to keep in mind with diesels is the maintenance costs are 3 to 4 times more than a gas truck. Diesel oil changes are 80-100 per change and fuel filters are 80-265 per year depending on the brand of truck. Not to mention the larger diesel trucks ride like a large diesel truck when not towing or empty.

Also as a side note reading through this last page or two it seems like people need to chill out a little bit. Whatever works for one peeps may not work for the next.

[jcl]

Originally Posted by Tuco

HP = Torque x RPM ÷ 5252

We have a vehicle sitting on flat ground and then moved to a 5% grade. Looking strictly at the drive wheels, what HP and Torque are required to hold that vehicle stationary? This is in general terms, i'm not looking for a real number here.

This should be interesting. We are talking wheel torque, not engine torque, if we look at the drive wheels as you suggest. The flywheel doesn’t enter into it. Here is a very chill approach

Can we agree that when the vehicle is on the level, no torque is required to hold it there? Similarly, no hp is required to hold it there.

Now the 5% grade. Ignore rolling friction for a moment. Because the truck wants to roll down the hill, a force is required to hold it on the hill. That force could be a linear pull, like a tow rope, or it could be a torque on the drive wheels. That torque is usually applied by the parking brake. It could also be applied by a cinder block chock, for that matter. I haven’t calculated it, since you asked for general terms, and there would have to be a lot of assumptions. Let’s just agree it would be a static torque. Hp in this case is easy. It is zero, since no work is being done, eg the truck isn’t going up the hill. Put another way, rpm is zero for the wheel, using the equation (which doesn’t need the brackets).

This should be intuitively obvious, since cinder blocks dont have hp ratings.

What is next? Since this one came down to the existence of a parking brake, how doe it help clarify questions of torque and hp in gas and Diesel engines?

[gypsydad]

Originally Posted by Kanusport

I am a huge fan of the ecoboost f150. It has tons of power and torque. One thing to keep in mind with diesels is the maintenance costs are 3 to 4 times more than a gas truck. Diesel oil changes are 80-100 per change and fuel filters are 80-265 per year depending on the brand of truck. Not to mention the larger diesel trucks ride like a large diesel truck when not towing or empty.

Also as a side note reading through this last page or two it seems like people need to chill out a little bit. Whatever works for one peeps may not work for the next.

Loved my F150 EB...got the F250 6.7L for the benefits of pulling a larger AS...disadvantages as mentioned are fuel cost, maintenance cost, parking, and of course price difference for the diesel. But, I bought it to pull the AS with plenty payload capacity and travel...which we are doing. By the way, the ride on the newer 3/4T and 1T Fords is great since they changed the suspension in 2017; but, if you don't need/want a diesel, I understand.

[Tuco]

Originally Posted by jcl

This should be interesting. We are talking wheel torque, not engine torque, if we look at the drive wheels as you suggest. The flywheel doesn’t enter into it. Here is a very chill approach

Can we agree that when the vehicle is on the level, no torque is required to hold it there? Similarly, no hp is required to hold it there.

Now the 5% grade. Ignore rolling friction for a moment. Because the truck wants to roll down the hill, a force is required to hold it on the hill. That force could be a linear pull, like a tow rope, or it could be a torque on the drive wheels. That torque is usually applied by the parking brake. It could also be applied by a cinder block chock, for that matter. I haven’t calculated it, since you asked for general terms, and there would have to be a lot of assumptions. Let’s just agree it would be a static torque. Hp in this case is easy. It is zero, since no work is being done, eg the truck isn’t going up the hill. Put another way, rpm is zero for the wheel, using the equation (which doesn’t need the brackets).

This should be intuitively obvious, since cinder blocks dont have hp ratings.

What is next? Since this one came down to the existence of a parking brake, how doe it help clarify questions of torque and hp in gas and Diesel engines?

Lets use the engine to supply the static torque to hold the vehicle stationary. Not that the other things mentioned wont work, but we want to get to to the end question. Again in general terms, HP and Torque now at the engine (and how does RPM come into play here).

HP x 5252
----------- = Torque
RPM

[jcl]

Originally Posted by Tuco

Lets use the engine to supply the static torque to hold the vehicle stationary. Not that the other things mentioned wont work, but we want to get to to the end question. Again in general terms, HP and Torque now at the engine (and how does RPM come into play here).

HP x 5252
----------- = Torque
RPM

Ok, but not sure how that will help.

Static torque at the flywheel implies the engine is stopped, so rpm is zero. Now you need a manual transmission, but that is better here anyways, because it takes the auto transmission out of the discussion, and the transmission is the same for both engine variants in any case.

There is now a flywheel torque requirement to stop the vehicle rolling, it isn’t zero. Hp is zero, as before, because rpm is zero.

Is that what you wanted?

Or are you planning on holding the automatic in gear to produce this driveline torque? If so, you need to figure out what the work is that is being done in the transmission and torque converter. That will involve both hp and torque, for both the level and 5% grade examples. The work that is being done here relates to the heat generated.

[GCinSC2]

But doesn’t this theoretical question also requiring including the tire size, rear axle ratio and transmission ratio to complete this equation?

I’m in the rare truck mode on this, my 2005 Dodge Cummins has a MANUAL trans so shouldn’t the torque required to hold position on the grade will be less in 5th as opposed to 6th etc. ?

If I’m pulling a significant grade on a highway like I-77 N from NC into VA Fancy Gap about 6 miles or so at 7% IIRC 5th gear does quite nice pulling about 18K lbs combined. Truck knows it has a job to do no way to bluff that but when it gets to the top back to 6th and the small eng temp increase comes right back down to normal.

Play nice ya’ll

Gary

[jcl]

Originally Posted by GCinSC2

But doesn’t this theoretical question also requiring including the tire size, rear axle ratio and transmission ratio to complete this equation?

I’m in the rare truck mode on this, my 2005 Dodge Cummins has a MANUAL trans so shouldn’t the torque required to hold position on the grade will be less in 5th as opposed to 6th etc. ?

If I’m pulling a significant grade on a highway like I-77 N from NC into VA Fancy Gap about 6 miles or so at 7% IIRC 5th gear does quite nice pulling about 18K lbs combined. Truck knows it has a job to do no way to bluff that but when it gets to the top back to 6th and the small eng temp increase comes right back down to normal.

Play nice ya’ll

Gary

I am making every effort to play nicely!

Yes, the gearing all the way from the rim to wherever it is measured impacts that torque measurement. So tire size, diff gearing, transmission gearing, all matter. Since the question poses that the truck is stationary, hp remains zero.

I see the question as a "is this zero" and "is this not zero" type of question. The specific values weren't requested. What is interesting is that in a discussion of flywheel torque (diesel vs gas) we have now established that gearing matters for performance, depending on what one is measuring. Said another way, you can't make hp, but you can make torque, all it takes is gearing.

Not sure where Dave is going with this, but we shall see

[Tuco]

Originally Posted by jcl

Ok, but not sure how that will help.

Static torque at the flywheel implies the engine is stopped, so rpm is zero. Now you need a manual transmission, but that is better here anyways, because it takes the auto transmission out of the discussion, and the transmission is the same for both engine variants in any case.

There is now a flywheel torque requirement to stop the vehicle rolling, it isn’t zero. Hp is zero, as before, because rpm is zero.

Is that what you wanted?

Or are you planning on holding the automatic in gear to produce this driveline torque? If so, you need to figure out what the work is that is being done in the transmission and torque converter. That will involve both hp and torque, for both the level and 5% grade examples. The work that is being done here relates to the heat generated.

I apologize if i'm not being clear or not moving fast enough. We can get into more meat and potatoes later. What I think we need to agree on is that there is a torque budget needed regardless of where we get it from (for now). I would also like to clarify what can affect that torque requirement. This is what I think, please add/comment on this (again K.I.S.S.).

1. % of Grade
2. Weight

To move things along, here is the next question to clarify. Now lets get the vehicle moving at 25 mph on level ground. Here we also have a torque and HP budget to overcome friction, wind, drive train losses and such. Excluding the torque (and HP) needed to overcome gravity in the 5% scenario, can we agree that this is the same number in both at the same speed (level ground and 5% grade)? Again, I may not be saying this clearly, but i'm trying.

[Albireo]

Originally Posted by gypsydad

Loved my F150 EB...got the F250 6.7L for the benefits of pulling a larger AS...disadvantages as mentioned are fuel cost, maintenance cost, parking, and of course price difference for the diesel. But, I bought it to pull the AS with plenty payload capacity and travel...which we are doing. By the way, the ride on the newer 3/4T and 1T Fords is great since they changed the suspension in 2017; but, if you don't need/want a diesel, I understand.

I agree with your other post about having a diesel 250 and what a pleasure it is with towing through the mountains and using the engine brake in conjunction with the cruise control. Fantastic!

As far as the ride. I sold my 2018 F150 to and bought my 2019 F250 and I enjoy the ride of the 250 much better. I find the steering has way less play and I enjoy the firm suspension and the feel of the road through the tires. I have mentioned this before.

The 150 is a fine vehicle but I took a friends experience (and others) and bought the larger diesel. He towed his race car for well over a decade all through the California mountains and with tires, gas and tools you are looking about 8000 pounds or so on the trailer. He has had at least 3 F150's and 3 F250's and his recommendation was to go with the F250 diesel. I also have a lot of real world experience and I am so pleased with my decision. There is no comparison ecoboost or not with towing between the two vehicles. Again, the F150 is a fine vehicle and will do the job. I just enjoy all the benefits of the 250 and of course each to his own.

One other thing. Thermometers have degrees and you know where you can stick them. Having owned and sold a very successful trucking company and being around men, trucks and towing I would take this experience over any formal education. Don't get me wrong I do value formal education buy when one starts quoting the physics I know I wouldn't want to get behind the wheel with that person. The are drivers and there are those who drive and there is a big difference. I know a few who start quoting physics and I rest my case.

[jcl]

Originally Posted by Tuco

I apologize if i'm not being clear or not moving fast enough. We can get into more meat and potatoes later. What I think we need to agree on is that there is a torque budget needed regardless of where we get it from (for now). I would also like to clarify what can affect that torque requirement. This is what I think, please add/comment on this (again K.I.S.S.).

1. % of Grade
2. Weight

To move things along, here is the next question to clarify. Now lets get the vehicle moving at 25 mph on level ground. Here we also have a torque and HP budget to overcome friction, wind, drive train losses and such. Excluding the torque (and HP) needed to overcome gravity in the 5% scenario, can we agree that this is the same number in both at the same speed (level ground and 5% grade)? Again, I may not be saying this clearly, but i'm trying.

I think there is confusion about what you call torque budget. There is a wheel torque requirement to hold it steady on the hill, regardless of factors such as transmission and torque converter, and I think we agree on that. Yes, it would relate to mass and slope.

I think we agree that there is no hp requirement, since the vehicle is not moving, so no work is being done.

On to part 2.

OK, now travel at a steady 25 mph. Ignore acceleration, just start the analysis at a steady 25 mph. There is a wheel torque requirement. If you mean that conceptually, it takes some torque to hold it on the hill, and then some incremental torque to move it forward up that hill, all other things being equal, then sure.

The issue is that this doesn't correlate to a flywheel torque requirement. I wouldn't use the phrase torque budget, because you could simply change gears (the flywheel torque requirement is variable; it is non zero, but it isn't coming out of a budget, which suggests a finite limit, because it is variable)

There is a hp requirement, to overcome all the things you list, and we agree that the base number is the same for both the hill and level ground examples; the difference is the work done in climbing the hill.

Perhaps instead of this step by step, you could lay out your thinking on why the level ground and 5% grades matter in an effort to understand the difference between hp and torque.

[jcl]

Originally Posted by Albireo

One other thing. Thermometers have degrees and you know where you can stick them. Having owned and sold a very successful trucking company and being around men, trucks and towing I would take this experience over any formal education. Don't get me wrong I do value formal education buy when one starts quoting the physics I know I wouldn't want to get behind the wheel with that person. The are drivers and there are those who drive and there is a big difference. I know a few who start quoting physics and I rest my case.

You can dismiss formal education if you like, but don't underestimate the value of that formal education when combined with things like mechanic training, a heavy duty truck license, and a career in the heavy equipment industry. Including selling and servicing those truck engines you bought (unless you bought Detroits, never sold those).

Saw your degree comment. I went to engineering school while two brothers were getting their provincial qualifications as automotive mechanics. Heard them all. Perhaps also note that the hp and torque discussion above isn't based on university degree education, it is part of the Grade 11 curriculum where I live (I helped my daughter with her homework) and so it is probably taught elsewhere in high school.

[Isuzusweet]

It's gas versus diesel, not education versus experience.
I have neither, but still manage to eek out a living, and try not to piss everyone off.[emoji6]
Cheers
Sidekick Tony

[Tuco]

Originally Posted by jcl

I think there is confusion about what you call torque budget. There is a wheel torque requirement to hold it steady on the hill, regardless of factors such as transmission and torque converter, and I think we agree on that. Yes, it would relate to mass and slope.

I think we agree that there is no hp requirement, since the vehicle is not moving, so no work is being done.

On to part 2.

OK, now travel at a steady 25 mph. Ignore acceleration, just start the analysis at a steady 25 mph. There is a wheel torque requirement. If you mean that conceptually, it takes some torque to hold it on the hill, and then some incremental torque to move it forward up that hill, all other things being equal, then sure.

The issue is that this doesn't correlate to a flywheel torque requirement. I wouldn't use the phrase torque budget, because you could simply change gears (the flywheel torque requirement is variable; it is non zero, but it isn't coming out of a budget, which suggests a finite limit, because it is variable)

There is a hp requirement, to overcome all the things you list, and we agree that the base number is the same for both the hill and level ground examples; the difference is the work done in climbing the hill.

Perhaps instead of this step by step, you could lay out your thinking on why the level ground and 5% grades matter in an effort to understand the difference between hp and torque.

I'll do my best here to accommodate your request (my wife would say "In a nutshell...Please?" ). Unless otherwise noted torque is measured at the drive wheels.

1. There is a torque requirement for slope and mass to overcome gravity. Lets call that "X". Mass will never be zero, but slope can be.

2. There is a torque requirement for steady state cursing. Lets call that "Y".

3. The total torque requirement will be X+Y, so lets call that total "Z"

The engine has a torque curve where it can provide a certain amount of torque at a given RPM. Gearing changes the amount of torque seen at the drive wheels (this is over simplified I know). At a given RPM if available engine torque is grater than "Z" then the engine has enough extra torque to spin faster and can increase RPM and HP. If available engine torque equals "Z" then you can't increase RPM and therefore cant get more HP, but it can maintain the RPM it has. If available engine torque is less than "Z" then RPM and HP drop until the engine stalls or you down shift. I will pause here for comment and input. (use cases will be next unless there is major disagreement)