Why not use gas engines?

Horsepower is how fast you hit the wall. Torque is how far you move the wall.

 

Sayings like this are a big part of the reason people don't understand how horsepower and torque relate. The correct version of this quote would read like this:

"Horsepower is how fast you hit the wall. Horsepower is also how far you move the wall."

Torque is an arbitrary number. Almost meaningless without RPM. Otherwise, there's no way to tell how useful it is. Let me give you an example:

You take a water wheel. It's spinning, and generating 2,400 lbs/torque at the output. That's a lot of torque, right? Thing is, it's only spinning at 30 RPM. That ends up being a whopping 14 horsepower. Not going to get much done. Same as diesel vs gas. If you have a gas burner with half the torque of a diesel, but for some reason they both output the same horsepower, it's because the gas engine is turning double the RPM of the diesel. They're equally as useful, but they'll require different gearsets.

 

Some make it hard, and its not.

Torque = work done.
HP = the speed that work gets done at.

Either is useless without the other. A semi truck with 5000 ft lbs of torque, and 1 hp would be useless.

 

Is that even possible?

At any rate power is just torque x's rpm,
In any given I C E the only way to make more power is to raise the RPM.
Then we get into manipulating either or.
.

 

It is possible. 5,000 lbs/torque at 1 RPM is 1 horsepower.

You're right on the rest. You raise your torque curve along the RPM, you increase horsepower. You don't even have to be making peak torque at a given RPM to do so. For example, you could make 1,650 lbs/tq at 1,000 RPM. That makes 314 horsepower. But take that same engine at 1,800 RPM where torque has fallen off a little. Now it's only making 1,400 lbs/tq at 1,800 RPM. That is 480 horsepower.

So if you get programming that increases your horsepower, but torque stays the same, they didn't do anything to actually increase the strength (torque) of the engine. To do so, you'd need to add fuel, and maybe even add air if you needed to control smoke and heat. What they must be doing then, is moving torque higher in the RPM range. That's as easy as increasing timing. And what you've done now is made the engine more "useful" without actually making it stronger.

Keep in mind all of this is just the math behind it. Has nothing to do with practicality. You could change timing so much that now you're out of your efficiency range for your gearing, and here you are wanting new differentials because your fuel mileage is suffering. Take gas vs diesel engines as another example. You could easily make a gas burner as "useful" as a diesel from a horsepower perspective, and just gear it accordingly. But you're going to get trash fuel mileage, and the engine isn't going to last very long in comparison to the diesel. Even if you design the gas engine to last forever, there's no getting around the fact that there's more BTU's per drop in diesel than gas, so you're leaving efficiency on the table.

There's a reason God prefers Diesels...

 

Torque is how you remove the cap off a beer bottle

 

I don't think you are changing the torque curve tho. you are raising the rpm but the torque curve is constant. Yes the torque would be lower past the peak torque curve but the curve itself is the same.

More torque equals more power but more power doesn't equal more torque.
The torque ''curve'' is why a smaller gas engine has less torque than a larger diesel engine but spins faster.
The internals of a diesel are much heavier on a diesel too so spinning it at 6000 rpm creates too much shock load.
At the crank torque of course. At the wheel torque can certainly be manipulated.
And I'm assuming all else being equal. Changing the parameters can alter both torque and power.

 

Diesel engines are alot heavier and built for the rigors of heavy work. A diesel is like an ox ready to pull a plow vs a gas engine thats like a cheetah that can go fast but couldnt pull any weight to save its life.

I wonder if engineers ever thought of an engine thats beyond diesel??

 

I just scanned the comments so I may be repeating. I have had mechanics, as well as engine designers, tell me that it breaks down into two things. First Diesel engines produce more torque at lower RPMs. And higher cylinder pressure leads to higher temperatures that lead to improved thermal efficiency. Added to the fact a diesel engine has no ignition system, it uses compression. These things lead to better longer life and a much-reduced cost per mile over the life of the engine. If it were not thanksgiving I could actually speak to a lady I know that designs these engines.

 

Peak torque is when you go to take a whiz in the morning and your heels lift up off the ground.