Gas vs Diesel Shootout in the Dunes & Sand

85_Ranger4x4

Well-known member
Generally in low third the ol 302 chants along at 1800 rpm cleaning tires in the mud/snow I drive in like a champ.

In what I do I have never had to really open it up beyond dieselish rpm while offroading.
 

nickw

Adventurer
If your transmission wants to downshift, you generally don't have enough power ( torque ). The downshift is a patch over the real issue.

No, opinion doesn't change with a manual transmission. No issues as long as the vehicle has sufficient power, specifically meaty low and mid range torque to get those big tires moving in deep sand.

Totally disagree with torque being a bad metric for power. It is THE metric for engine power. Meat under the curve. I could care less about peak HP way out at the end of the RPM curve. I think of it like a sport bike engine. They make 200+hp per liter now.....but they would make a TERRIBLE Jeep engine because that happens at like 10,000+ rpm and make very limited power down low. That just doesn't work for big heavy vehicles with big heavy tires.

If you want to post an observation, that's great, but not everyone is going to have the same opinion. Most combustion engine tech is moving to meet somewhere in the middle. Diesel engines are finding ways to make broader power with increased RPM range and less lag from the forced induction systems. Gas engines are using direct injection and higher compression ratios ( getting closer to diesel numbers ) along with variable valve technology to increase low end power. Every driver loves that low to mid rpm torque pull. It also works really good for increasing mileage when you can push a vehicle along at highway speed using double overdrives at only 1500rpm.
Torque is NOT power.....that is a fundamental concept. Torque by itself is a meaningless metric to compare engines. For instance, which engine would you select to power a huge industrial offroad rig:

Option 1:
4000 ft lbs / 150 hp

Option 2:
2000 ft lbs / 500 hp

Option 3:
350 ft lbs / 1500 hp

We are talking effective RPM range, with a manual it would require a diesel engine to upshift to get sim wheel speed as a petrol in a single gear....you see it often with the big mud bog trucks.
 

calicamper

Expedition Leader
Don’t desert dwellers have dozens of names for sand? Reason being there are many types of sand. There are sands that support heavy vehicles and there are sands that eat heavy vehicles. Knowing which is which and your vehicle can determine when you know your in over your head and when your not. But never has anyone said I wish my sand vehicle was heavier.
 

Metcalf

Expedition Leader
Torque is NOT power.....that is a fundamental concept. Torque by itself is a meaningless metric to compare engines. For instance, which engine would you select to power a huge industrial offroad rig:

Option 1:
4000 ft lbs / 150 hp

Option 2:
2000 ft lbs / 500 hp

Option 3:
350 ft lbs / 1500 hp

We are talking effective RPM range, with a manual it would require a diesel engine to upshift to get sim wheel speed as a petrol in a single gear....you see it often with the big mud bog trucks.
Torque is a great metric for me when talking engines. Seeing how you can't even determine HP without knowing torque and rpm. I could care less typically what happens over 5252.

Again, if the engine doesn't make enough torque to start in the gear you want your point about shifting is very moot. This is very very common on vehicles with gas engines and high peak power. You where the one that didn't want to take 'special' case engines like I had posted.....race engines or whatever. Engines with high rpm horsepower commonly have to use things like high stall converters to get into their power band generating more heat. No thanks. I'll take broad power with high low and mid range torque. Modern diesels do that rather well. Modern gas V8s also make good low and mid range V8.....displacement, VVT, higher compression, direct injection.....starting to sound kinda like a modern diesel.
 

billiebob

Well-known member
Excuses? Very strange comment / way to put it, I'm just stating what I've seen without having to google it on YouTube. If anything your post comes across as defensive, but again, this is a quantitative / pratical discussion not an emotional one.....

I'd disagree, most Gas / Petrol rigs have much different powerbands.....always exceptions (as all your examples seem to be), but generally gas has more HP at higher RPM, both of which are good for sand based on my experience and observations.

Gas rigs generally have a higher HP / weight and broader powerband. For most rigs, diesels have lower HP vs gas so I'd disagree there is not a difference in power....for full size trucks they are close, but for many other vehicle types Gas engines are generally more 'powerful' across a broader RPM. Using the Jeep gas vs diesel:

Diesel 3.0; 260 hp @ 3600 RPM (effective range 1300 to 3600); spread of 2300
Gas 3.6; 285 hp @ 6400 RPM (effective range 2000 to 6400); spread of 4400

Doesn't get much different than that, using the example you gave, that's what, ~85%+ more RPM range, which can be important in mud and sand.

Same story for full size rigs, but more extreme, look at Ford:

Diesel 6.7; 475 hp @ 2600 RPM (range 1000 to 2600); spread of 1600
Gas 7.3; 455 hp @ 5500 RPM (range 2000 to 5500); spread of 3500

More than 2x.....
And that ^^^ is what this post is all about.
Well said Nick.

I'm starting to think the diesel fanatics missed Reading Comprehension 101 in Grade 10..... diesels have their place but accelerating in loose sand is not one of them..... in sand, weight is the one thing to reduce and rapid rpm acceleration is the thing to exploit. The diesel does neither.

Something for the diesel fanatics to consider..... has there ever been a diesel win the Indy 500.... or Daytona 500.... or any Formula One race.... ever ??
And before reacting, read the opening Post #1.
 
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Betarocker

Adventurer
And that ^^^ is what this post is all about.
Well said Nick.

I'm starting to think the diesel fanatics missed Reading Comprehension 101 in Grade 10..... diesels have their place but accelerating in loose sand is not one of them..... in sand, weight is the one thing to reduce and rapid rpm acceleration is the thing to exploit. The diesel does neither.

Something for the diesel fanatics to consider..... has there ever been a diesel win the Indy 500.... or Daytona 500.... or any Formula One race.... ever ??
And before reacting, read the opening Post #1.
Rapid tire acceleration from a stop in sand typically leads to digging a hole, regardless of the fuel source.

Indy, Nascar, and F1 have very strict rules regarding engines and/or fuel.
Diesels won Lemans 24 hours over and over, even when being penalized with adding weight and reduced fuel cell size . Dakar Rally has too been won by diesels.
 

nickw

Adventurer
Torque is a great metric for me when talking engines. Seeing how you can't even determine HP without knowing torque and rpm. I could care less typically what happens over 5252.

Again, if the engine doesn't make enough torque to start in the gear you want your point about shifting is very moot. This is very very common on vehicles with gas engines and high peak power. You where the one that didn't want to take 'special' case engines like I had posted.....race engines or whatever. Engines with high rpm horsepower commonly have to use things like high stall converters to get into their power band generating more heat. No thanks. I'll take broad power with high low and mid range torque. Modern diesels do that rather well. Modern gas V8s also make good low and mid range V8.....displacement, VVT, higher compression, direct injection.....starting to sound kinda like a modern diesel.
Can't answer the question? I even threw you a bone and included HP. Yeah I'm trying to prove a point, but you gotta play along. No race engines here.

HP = torque potential at wheels.

Torque is worthless without knowing RPM, when you include both....you get HP.

Can you name a modern gas engine that can't start from a dead stop due to lack of torque? I cant!
 

nickw

Adventurer
Rapid tire acceleration from a stop in sand typically leads to digging a hole, regardless of the fuel source.

Indy, Nascar, and F1 have very strict rules regarding engines and/or fuel.
Diesels won Lemans 24 hours over and over, even when being penalized with adding weight and reduced fuel cell size . Dakar Rally has too been won by diesels.
Lots of cool diesels, they are mainly used due to fuel economy. Didn't they have to bend a bunch of rules to allow diesels to be competitive in LeMans? Turbos being one of them?

High torque at low RPM and turbo lag are recipes for wheel spin.
 

Metcalf

Expedition Leader
Something for the diesel fanatics to consider..... has there ever been a diesel win the Indy 500.... or Daytona 500.... or any Formula One race.... ever ??
And before reacting, read the opening Post #1.
When did they start racing those in sand again? Look at any rally race in the sand, especially long distance ones like Dakar, and every class has strong finishes or winners that are diesel. Strange....
 

Metcalf

Expedition Leader
Can't answer the question? I even threw you a bone and included HP. Yeah I'm trying to prove a point, but you gotta play along. No race engines here.

HP = torque potential at wheels.

Torque is worthless without knowing RPM, when you include both....you get HP.

Can you name a modern gas engine that can't start from a dead stop due to lack of torque? I cant!
Oh I can, I just don't like playing dumb theorecical games with the goal posts moved out so far it doesn't matter.

The point about starting from a dead stop is about gearing, always has been. If you have to use shorter gear because your engine doesn't make good low to mid power you give up a lot of your magical rpm range potential. TONS of real world vehicles have these issues....everything from the 3.6 gas Jeep we have been talking about to old 4cyl gas toyota trucks, Suzuki Samurais. Modern UTVs also have to gear around this issue with rubber band clutches and CVT gearboxes. Meh.

Give me meaty low and mid range Torque, especially if we are talking about large aired down tires in the sand. Any semi-modern diesel engine can do that in spades. A larger displacement gas V8 can too. Smaller gas 4cyl and 6cyl engines don't do it for me in most vehicles ( even if they make close to the same peak HP way up near redline )......especially as weight and tire size goes up. We have limited options in the USA generally.

I'm pretty much out unless you have something new. I've stated my opinion.
 

nickw

Adventurer
Oh I can, I just don't like playing dumb theorecical games with the goal posts moved out so far it doesn't matter.

The point about starting from a dead stop is about gearing, always has been. If you have to use shorter gear because your engine doesn't make good low to mid power you give up a lot of your magical rpm range potential. TONS of real world vehicles have these issues....everything from the 3.6 gas Jeep we have been talking about to old 4cyl gas toyota trucks, Suzuki Samurais. Modern UTVs also have to gear around this issue with rubber band clutches and CVT gearboxes. Meh.

Give me meaty low and mid range Torque, especially if we are talking about large aired down tires in the sand. Any semi-modern diesel engine can do that in spades. A larger displacement gas V8 can too. Smaller gas 4cyl and 6cyl engines don't do it for me in most vehicles ( even if they make close to the same peak HP way up near redline )......especially as weight and tire size goes up. We have limited options in the USA generally.

I'm pretty much out unless you have something new. I've stated my opinion.
It's a simple real world example that no, you can't answer, I know that and so do you.

I did calculations trying to form an opinion based on quantitative data....you can even see I used different starting points for RPM, 1000 for diesel and 2000 for petrol to normalize that they do have different power levels at low RPM. No emotion, just trying to qualify what I see with data.

I was trying to have an adult conversation, not sure why you are taking it so personally.
 

nickw

Adventurer
When did they start racing those in sand again? Look at any rally race in the sand, especially long distance ones like Dakar, and every class has strong finishes or winners that are diesel. Strange....
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.
 

NevadaLover

Forking Icehole
Our local dunes recreation area gets hit pretty hard during spring, big heavy diesels pull huge toy haulers over the smaller dunes to camp on the flatpans away from the highway and the parking area, big tires aired down being spun with big torque makes it a pretty easy job, the toys that tear up the big dunes are all gassers and fly over the sand, my point is that both motors have their place in this fun and fill the need admirably.
 

Peter_n_Margaret

Adventurer
If you need revs, you have too much air in my view. If you can't crawl up you cause track damage.
No wheel spin, no screaming engines.

The scolloping of this track is caused by too much air and wheel spin.

Cheers,
Peter
OKA196 motorhome
Just for completeness, my vehicle weighs between 6 and 6.5T (14,000lbs). It is powered by a 28 year old 4 cylinder diesel that develops a maximum of 81kW of power (110HP) at 2,800RPM (I never rev it that high) and a maximum of 354Nm (261ft lbs) of torque at 1,600rpm.
Whether it goes up a sand dune or not depends, on the sand, the tyre pressures and the gear selected.
In the attached vids, I would be driving at a constant engine speed of around 2,000 - 2,200rpm.
We drive on a lot of sand of all types, both in the desert and on beaches.
Cheers,
Peter
OKA196 motorhome
 

Metcalf

Expedition Leader
Can't answer the question? I even threw you a bone and included HP. Yeah I'm trying to prove a point, but you gotta play along. No race engines here.

HP = torque potential at wheels.

Torque is worthless without knowing RPM, when you include both....you get HP.

Can you name a modern gas engine that can't start from a dead stop due to lack of torque? I cant!
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.
 
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