Gas vs Diesel Shootout in the Dunes & Sand

[Metcalf]

Largely due to fuel economy, if you care about $$ or range, diesel is the way to go.

Again, we are talking normal rigs, I think you brought up all these unique, custom, factory sponsored race rigs.

Nice edit of the post. I was quoting the post about racing, not using it as an example.

Seeing as we are on an expedition forum, I would say range is pretty important to most people.

 

[nickw]

Nice edit of the post. I was quoting the post about racing, not using it as an example.

Seeing as we are on an expedition forum, I would say range is pretty important to most people.

Edit of the post?

Reread the original post, you've steered this conversation in an odd way...it is about performance in dunes, not the way a vehicle makes you feel.

 

[nickw]

Your 'real world' examples are anything but in the automotive world.

Horsepower = Torque x RPM / 5,252

I never said I didn't need to know RPM, I said I didn't really care about what happens over 5252, and I still don't.

I named a bunch of common vehicles that have a hard time time turning big tires in sand. They have to commonly use deeper gearing to do so, and don't have the torque to pull taller gearing when needed. This isn't really rocket science or anything. I know what I like to look for in off road vehicle powerbands. I have tried a lot of different combos over the years. I still like meaty low and mid range torque.

I have a grasp of how HP is calculated, thanks for reminder. Why pick 5252? Nothing wrong with using power if it's available, engines are designed that way by folks smarter than you or I.

I find it funny that you make (incorrect) claims but can't answer a fair simple question. Not answering proves the point I suppose, you are not adding much at this point, Id say carry on someplace else, thanks.

 

[Betarocker]

I have a grasp of how HP is calculated, thanks for reminder. Why pick 5252? Nothing wrong with using power if it's available, engines are designed that way by folks smarter than you or I.

I find it funny that you make (incorrect) claims but can't answer a fair simple question. Not answering proves the point I suppose, you are not adding much at this point, Id say carry on someplace else, thanks.

5252 is not a randomly chosen number, it is a constant derived from the vertical linear force to radial. One horsepower is defined as lifting 550 pounds one foot in one second. ((550pounds / 2) x 60seconds) / Pi = 5252. Since the rotational count is RPM, (rotations per minute), and most people know there a 60 seconds in a minute, that's where that value arises from.
Torque is the measurable value to determine the rotational force of a spinning object. A dynamometer measures the torque at the wheels or crankshaft, and through calculations (usually computer software) determines the horsepower at a given engine rotation.

Now to your point to usable revs.
Let's use a basic Chevy 350ci engine. Idle about 850rpm, Redline is about 5500rpm, but optimum cruising engine speed is 2500rpm, with crawl down to 2000rpm. Usable revs are 3500rpm. 300HP / 380 lb-ft.
I'll use my truck as an example for the diesel, 6.7L Powerstroke. Idle 600rpm, Redline 4000rpm, cruising engine speed is 1100rpm, with crawl down to 800rpm. Usable revs are 3200rpm. 425HP / 975 lb-ft.

I want to revisit your opening post about your observations about diesels struggling and gassers not. Were you actually comparing scientifically? ie. Dodge Ram 2500 Quad Cab short box with the only difference is one having a diesel, and the other having a gas? Or were you comparing apples to marbles? ie. A bone stock Ram 3500 QC SB with fully aired up 80psi 265/70-17 tires against 3.5L Ecoboost Raptor with it's 315/70-17 aftermarket mud terrains aired down to 20psi?

 

[nickw]

5252 is not a randomly chosen number, it is a constant derived from the vertical linear force to radial. One horsepower is defined as lifting 550 pounds one foot in one second. ((550pounds / 2) x 60seconds) / Pi = 5252. Since the rotational count is RPM, (rotations per minute), and most people know there a 60 seconds in a minute, that's where that value arises from.
Torque is the measurable value to determine the rotational force of a spinning object. A dynamometer measures the torque at the wheels or crankshaft, and through calculations (usually computer software) determines the horsepower at a given engine rotation.

Now to your point to usable revs.
Let's use a basic Chevy 350ci engine. Idle about 850rpm, Redline is about 5500rpm, but optimum cruising engine speed is 2500rpm, with crawl down to 2000rpm. Usable revs are 3500rpm. 300HP / 380 lb-ft.
I'll use my truck as an example for the diesel, 6.7L Powerstroke. Idle 600rpm, Redline 4000rpm, cruising engine speed is 1100rpm, with crawl down to 800rpm. Usable revs are 3200rpm. 425HP / 975 lb-ft.

I want to revisit your opening post about your observations about diesels struggling and gassers not. Were you actually comparing scientifically? ie. Dodge Ram 2500 Quad Cab short box with the only difference is one having a diesel, and the other having a gas? Or were you comparing apples to marbles? ie. A bone stock Ram 3500 QC SB with fully aired up 80psi 265/70-17 tires against 3.5L Ecoboost Raptor with it's 315/70-17 aftermarket mud terrains aired down to 20psi?

Good convo.

I get the 5252 constant, which is why torque is a useless metric for comparison, my question was around why pick that as something not to rev past? Engines don't have a limit there.

We should at least compare engines of sim era and not pick the best and worst case scenarios, Idle to max HP I'd consider usable range, more fuel above max hp wont aid in acceleration.

Duramax is 1000 rpm to hp max of 2800, so 1800 range, we can call it 800 rpm at lower end and push total range to 2000.

Hemi is 2000 rpm (mine cruises at 1700) to hp max at 5800, lets use 2500 as low end, thats 3300 range

2000 vs 3300 BEST CASE, it's significant, it's easily a gear change.

I'm just trying to put some math around what I see, maybe I'm off base. Like for like, sim rigs.

Problem gets worse with some of the larger industrial type rigs that rev even lower.

 

[Betarocker]

Good convo.

I get the 5252 constant, which is why torque is a useless metric for comparison, my question was around why pick that as something not to rev past? Engines don't have a limit there.

We should at least compare engines of sim era and not pick the best and worst case scenarios, Idle to max HP I'd consider usable range, more fuel above max hp wont aid in acceleration.

Duramax is 1000 rpm to hp max of 2800, so 1800 range, we can call it 800 rpm at lower end and push total range to 2000.

Hemi is 2000 rpm (mine cruises at 1700) to hp max at 5800, lets use 2500 as low end, thats 3300 range

2000 vs 3300 BEST CASE, it's significant, it's easily a gear change.

I'm just trying to put some math around what I see, maybe I'm off base. Like for like, sim rigs.

Problem gets worse with some of the larger industrial type rigs that rev even lower.

5252 is not the RPM. It is a constant in the calculation. Whatever engine, let's say an F1 race engine makes 260lb-ft at 16000rpm. HP = 260tq * 16000rpm / 5252(no unit)= 792HP

Torque is THE metric and horsepower is a derivative of it. Without torque there is no horsepower. This is simple physics, not opinion. Mass, distance & time are the basic quantities of physics. All other quantities in mechanics can be expressed in terms of these three. Torque is a measure of the force that can cause an object to rotate about an axis.

 

[Metcalf]

I have a grasp of how HP is calculated, thanks for reminder. Why pick 5252? Nothing wrong with using power if it's available, engines are designed that way by folks smarter than you or I.

I find it funny that you make (incorrect) claims but can't answer a fair simple question. Not answering proves the point I suppose, you are not adding much at this point, Id say carry on someplace else, thanks.

Yup, you just don't seem to get it. Cheers. Looks like you have some other people to annoy with your blinder view of how all this stuff works.

 

[nickw]

5252 is not the RPM. It is a constant in the calculation. Whatever engine, let's say an F1 race engine makes 260lb-ft at 16000rpm. HP = 260tq * 16000rpm / 5252(no unit)= 792HP

Torque is THE metric and horsepower is a derivative of it. Without torque there is no horsepower. This is simple physics, not opinion. Mass, distance & time are the basic quantities of physics. All other quantities in mechanics can be expressed in terms of these three. Torque is a measure of the force that can cause an object to rotate about an axis.

Its 100% RPM, that is where they cross bud, I know the math. You missed Metcalfs point, he said he wouldn't rev past that inflection point, which doesn't make sense.

In a geared system, HP creates tractive effort or torque at wheels. Knowing torque without RPM is useless. When comparing engines we look at power, HP, KW, etc.

I love using the example of a M1 Abrams Tank, @Metcalf wasnt being a sport, but the engine has less torque than many modern SUVs, in the neighborhood of 350 ft lbs....but it has 1500 hp, doesn't struggle to pull around a 60t tank.

People seem to get very confused between POWER and FORCE

And before you go google it and tell me I'm wrong, it has a huge reduction gearbox 7.5:1, on the engine, the engine is spinning at 20k+...

Steam engines are at opposite end of spectrum, HUGE torque (they are considered a constant torque engine) very low RPM, low HP and wouldn't stand a chance compared to modern vehicles.

 

[Metcalf]

Its 100% RPM, that is where they cross bud, I know the math. You missed Metcalfs point, he said he wouldn't rev past that inflection point, which doesn't make sense.

In a geared system, HP creates tractive effort or torque at wheels. Knowing torque without RPM is useless. When comparing engines we look at power, HP, KW, etc.

I love using the example of a M1 Abrams Tank, @Metcalf wasnt being a sport, but the engine has less torque than many modern SUVs, in the neighborhood of 350 ft lbs....but it has 1500 hp, doesn't struggle to pull around a 60t tank.

People seem to get very confused between POWER and FORCE

And before you go google it and tell me I'm wrong, it has a huge reduction gearbox 7.5:1, on the engine, the engine is spinning at 20k+...

Steam engines are at opposite end of spectrum, HUGE torque (they are considered a constant torque engine) very low RPM, low HP and wouldn't stand a chance compared to modern vehicles.

....and you wonder why people don't want to play your silly games....because they are silly. Then you complain about me pulling real world automotive examples.

I picked 5252 very specifically. It only took you about two pages to start to catch on.

Have fun with your tanks or whatever.

 

[nickw]

....and you wonder why people don't want to play your silly games....because they are silly. Then you complain about me pulling real world automotive examples.

I picked 5252 very specifically. It only took you about two pages to start to catch on.

Have fun with your tanks or whatever.

LOL - I thought you were gone? Silly game of knowing torque isn't power? The tank example, turbine in this case, shows how irrelavant torque is unlike your previous ascertation, so I guess you agree with me now? With all due respect, you said you were out, you are not adding anything anymore and I personally am not getting anything out of your posts, so take your own advice....

 

[Peter_n_Margaret]

And an EV has 100% torque at zero RPM.

I choose a diesel for my expedition truck because of superior economy, range, fire safety (big item), fuel availability in remote areas, torque, reliability, life,...........
Only ever owned one and would not want to go back.
Now the town shopping car is a different question entirely.
Cheers,
Peter
OKA196 motorhome

 

[Metcalf]

LOL - I thought you were gone? Silly game of knowing torque isn't power? The tank example, turbine in this case, shows how irrelavant torque is unlike your previous ascertation, so I guess you agree with me now? With all due respect, you said you were out, you are not adding anything anymore and I personally am not getting anything out of your posts, so take your own advice....

I'm back.......isn't the internet great.....

I'll say it slow again. You cannot determine HP without knowing what torque is. So it can never be 'irrelevant'. WHERE the engine produces torque is the key. There has to be a balance between the two. That balance crosses over at 5252.....get it now? Why do you think pretty much every vehicle manufacturer has been prioritizing making more low and mid range torque ( even on gas engines ) vs making more peak HP and extending RPM range. Anyone can go stick a super large lift, large duration cam in just about any engine to make more peak HP farther out in the RPM range. Why aren't they just doing that?

My posts aren't for you, they are for all the people that may be reading this thread. I don't want them to be getting bad one sided advice.

Focusing on peak HP ( and at a very high RPM mind you ) is an absolutely ridiculous concept, especially in the context of prepping a vehicle for off-road travel, even in the sand/desert.

 

[nickw]

I'm back.......isn't the internet great.....

I'll say it slow again. You cannot determine HP without knowing what torque is. So it can never be 'irrelevant'. WHERE the engine produces torque is the key. There has to be a balance between the two. That balance crosses over at 5252.....get it now? Why do you think pretty much every vehicle manufacturer has been prioritizing making more low and mid range torque ( even on gas engines ) vs making more peak HP and extending RPM range. Anyone can go stick a super large lift, large duration cam in just about any engine to make more peak HP farther out in the RPM range. Why aren't they just doing that?

My posts aren't for you, they are for all the people that may be reading this thread. I don't want them to be getting bad one sided advice.

Focusing on peak HP ( and at a very high RPM mind you ) is an absolutely ridiculous concept, especially in the context of prepping a vehicle for off-road travel, even in the sand/desert.

Bad one sided advice...you mean your advice of torque = power? Nobody cares about you, me or this thread....trust me, your opinion is not that important nor is mine. It was an open discussion, but you've made it about you for some reason.

Once more, you can't 'compare' engines based on torque when gearing is involved, torque alone tells you nothing. What we care about is HP, specifically the HP curve or area under the curve, especially when it comes to sand driving.

I'll take higher HP lower weight vehicle, it's power to weight ratio not torque to weight ratio that is going to win in the dunes.

We can play the same silly argument backwards, why don't guys focused on offroading unilaterally use diesel engines?

I'm not going in circles anymore - it it makes you feel good to have the last word, have at it.

 

[Peter_n_Margaret]

why don't guys focused on offroading unilaterally use diesel engines?

I reckon they do, everywhere in the world except the USA.
Cheers,
Peter
OKA196 motorhome

 

[nickw]

I reckon they do, everywhere in the world except the USA.
Cheers,
Peter
OKA196 motorhome

Not so quick, ever been to Dubai? Sand capital of the world, LOTS of petrol rigs.