SCVJeff
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Re: Torque vs. Horsepower
- Thread starter Mc2guy
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naterv
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This is my take on this topic:
Horsepower is a function of torque. If you do not have torque, you cannot have horsepower. You can have torque without horsepower. Torque is a twisting force. Like pushing on the handle of a wrench, and the twisting force of the wrench to the bolt. Before the bolt is broken loose, it does not move. Horsepower is how fast something can get done. Like how fast you can accelerate through the 1/4 mile. Or the speed at which you can go up a hill.
It is impossible to separate horsepower from torque when talking about internal combustion engines that must run to make torque, or to ask which is better since horsepower is function of torque.
Perhaps it would be more appropriate to ask, which is better, high RPM horsepower, or low RPM horsepower. When an engine is measured for torque and horsepower, a graph can be drawn with measurements at different RPM's. When these data points are connected, a curve is produced on a graph. When looking at torque and horsepower curves, horsepower always follows the torque curve. If an engine creates torque at a higher RPM, it also creates horsepower at a higher RPM. If an engine creates torque at a lower RPM, it will also create horsepower at a lower RPM. If and engine creates torque throughout the RPM spectrum like an electric motor, it will make horsepower all over as well. All over, except at 0 RPM. It is impossible to make horsepower at 0 RPM. The peak horsepower will always occur at the higher RPM end of the torque curve, usually as the torque curve is falling off. This is because horsepower is a function of torque and RPM. The higher you can make torque in the RPM range, the more horsepower it will make.
I think some people get confused about torque because of the way torque is talked about in magazines, and when people describe how their engine feels and how it pulls. Typically, when an engine is described as "torquey", it makes it's torque and horsepower at a lower RPM, like diesels. Ultimately, it is the horsepower that is felt. But horsepower is made up of torque and RPM, so it is not wrong to call it torque.
For a RV, having your torque and horsepower at a lower RPM is advantageous and desirable. That's why so many people like diesels. Lower RPM's means less loss to friction, less heat, and less wear and tear on the engine.
If you have ever shopped for gasoline engine camshafts, you will sometimes see some labeled "RV cam" or "RV profile". These cams are designed to shift your torque and horsepower to a lower RPM. Since it is shifting the curves to a lower RPM, the net effect will be lower horsepower, because the RPM's are lower. But at lower RPM's, the engine will likely make more horsepower at a given RPM, say 2300 RPM. In RV use, this will give the RV more useable power without having to downshift and run the engine at a sky-high RPM to get it over the hill. A "racing" camshaft will shift the curves to a higher RPM. It will have more horsepower, BUT, it will be at a higher RPM. If you put such an engine in an RV, yes, it will accelerate faster, and have a higher top speed, only if you run it at these higher RPM's, like 6,000 RPM, but it will create so much heat and wear out so fast, it would not be worth it. No one wants to operate their RV at 6,000 RPM all the time.
The bottom line is horsepower is what you want, but you want the most horsepower possible at as low a RPM as possible. When comparing engines, it really is only fair to compare horsepower curves and their relative RPM's.
Horsepower gives you faster acceleration, and gets you over the hill faster. Torque is what makes that horsepower at a given RPM.
In general:
diesel = low RPM horsepower
Gasoline = higher RPM horsepower
Electric = low & high RPM horsepower
I think diesels have become so popular lately because of the turbo charger. Any diesel you ride in that you think has a lot of power, is likely to be a turbo diesel.
If manufacturers put turbos on giant gasoline V-8's and V-10's and designed them to run at low RPM's, you'd have a very nice gas powered RV. But manufacturers apparently haven't thought of this.
Horsepower is a function of torque. If you do not have torque, you cannot have horsepower. You can have torque without horsepower. Torque is a twisting force. Like pushing on the handle of a wrench, and the twisting force of the wrench to the bolt. Before the bolt is broken loose, it does not move. Horsepower is how fast something can get done. Like how fast you can accelerate through the 1/4 mile. Or the speed at which you can go up a hill.
It is impossible to separate horsepower from torque when talking about internal combustion engines that must run to make torque, or to ask which is better since horsepower is function of torque.
Perhaps it would be more appropriate to ask, which is better, high RPM horsepower, or low RPM horsepower. When an engine is measured for torque and horsepower, a graph can be drawn with measurements at different RPM's. When these data points are connected, a curve is produced on a graph. When looking at torque and horsepower curves, horsepower always follows the torque curve. If an engine creates torque at a higher RPM, it also creates horsepower at a higher RPM. If an engine creates torque at a lower RPM, it will also create horsepower at a lower RPM. If and engine creates torque throughout the RPM spectrum like an electric motor, it will make horsepower all over as well. All over, except at 0 RPM. It is impossible to make horsepower at 0 RPM. The peak horsepower will always occur at the higher RPM end of the torque curve, usually as the torque curve is falling off. This is because horsepower is a function of torque and RPM. The higher you can make torque in the RPM range, the more horsepower it will make.
I think some people get confused about torque because of the way torque is talked about in magazines, and when people describe how their engine feels and how it pulls. Typically, when an engine is described as "torquey", it makes it's torque and horsepower at a lower RPM, like diesels. Ultimately, it is the horsepower that is felt. But horsepower is made up of torque and RPM, so it is not wrong to call it torque.
For a RV, having your torque and horsepower at a lower RPM is advantageous and desirable. That's why so many people like diesels. Lower RPM's means less loss to friction, less heat, and less wear and tear on the engine.
If you have ever shopped for gasoline engine camshafts, you will sometimes see some labeled "RV cam" or "RV profile". These cams are designed to shift your torque and horsepower to a lower RPM. Since it is shifting the curves to a lower RPM, the net effect will be lower horsepower, because the RPM's are lower. But at lower RPM's, the engine will likely make more horsepower at a given RPM, say 2300 RPM. In RV use, this will give the RV more useable power without having to downshift and run the engine at a sky-high RPM to get it over the hill. A "racing" camshaft will shift the curves to a higher RPM. It will have more horsepower, BUT, it will be at a higher RPM. If you put such an engine in an RV, yes, it will accelerate faster, and have a higher top speed, only if you run it at these higher RPM's, like 6,000 RPM, but it will create so much heat and wear out so fast, it would not be worth it. No one wants to operate their RV at 6,000 RPM all the time.
The bottom line is horsepower is what you want, but you want the most horsepower possible at as low a RPM as possible. When comparing engines, it really is only fair to compare horsepower curves and their relative RPM's.
Horsepower gives you faster acceleration, and gets you over the hill faster. Torque is what makes that horsepower at a given RPM.
In general:
diesel = low RPM horsepower
Gasoline = higher RPM horsepower
Electric = low & high RPM horsepower
I think diesels have become so popular lately because of the turbo charger. Any diesel you ride in that you think has a lot of power, is likely to be a turbo diesel.
If manufacturers put turbos on giant gasoline V-8's and V-10's and designed them to run at low RPM's, you'd have a very nice gas powered RV. But manufacturers apparently haven't thought of this.
Naterv,
Seems like you have given the best description here, at least for me. Seems like it comes down to not hp or torque, but rather at what rpm they are developed.
Maybe the best setup would be a big electric motor, and a very long extension cord. ;D
Seems like you have given the best description here, at least for me. Seems like it comes down to not hp or torque, but rather at what rpm they are developed.
Maybe the best setup would be a big electric motor, and a very long extension cord. ;D
jrshall said:
Or a constant speed small well tuned turbo diesel mated to a big generator and then use multiple electric motors for both propulsion and braking. Then a pack of lithium Ion batteries to store the energy generated by stopping.
just like the train locomotives that deliver our freight every day.
If we get really fancy we can use a turbine instead of the diesel ;D
Kevin
Well-known member
naterv, but what about the hampsters? ;D
zukIzzy said:
Now THATS what I am talking about. I have been a huge fan of microturbine technologies given their ability to generate a ton of power at a low weight. Mated to an AC electric drivetrain, now your talking my language. Hopefully in my lifetime
I have seen commercial microturbines in action and they have come a long way since the 1960s. Heck, the Army uses smaller (not micro) PW turbine motors in the M1 tank and air support vehicles (helicopters), so it isn't science fiction, it just isn't cheap either...
naterv
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kevin said:
Speaking on hampsters, when I was a young lad, our family went on vacation & left the hampsters (I think 3 of them) in the bathtub. We left plenty of food, and affixed a small bowl under the faucet, and turned it on just so it would drip every few seconds.
When we got home, we found the hampsters had made a hampster nest over the drain and plugged it up. It's amazing how much that bathtub filled up. Sad to say, all the hampsters did not make it, and were found floating.
"There's no replacement for displacement" used to be the ad for the 1967 Plymouth GTX, which in 1967, the 440 was the king of displacement. Correct me if I'm wrong, but I believe the Chevy 454 didn't come along until 1970, Cadillac 472 in 1968, Cadillac 500 not until 1970, Ford 460 came in 1968, Buick 455 in 1970, Pontiac 455 in 1970, Olds 455 1968. The 440 came as the standard engine in the 1967 GTX. Strange how Chrysler corporation never tried to "one-up" everyone else again after the 440.
What does this have to do with RV's you might ask? Well, displacement is still the king. And so is compression.
Back in the day, a Chevy 350 might have beat a Chevy 454 for several reasons. Typically a 350 would have a higher power to weight ratio. And, typically, a 350 would have a higher compression ratio than a 454. But we are not talking about drag racing here, we're talking about RV's, but the same principles apply.
Remember, the more fuel and air an internal combustion engine can efficiently burn, the more power it's going to make. One way of doing this is by supercharging or turbocharging. Supercharging and turbocharging are ways to artificially increase the displacement of an engine. Since it takes more fuel to make more horsepower, horsepower isn't free. When you exploit all those ponies, your MPG will go down the tubes.
Weight is the enemy to horsepower. If you can manage to lighten your load, it's like adding free horsepower to your rig. I realize that's not an easy thing to do, because we all like the luxuries we pack around.
Marc L
Well-known member
naterv said:
That is so true. As soon as I unhook my trailer, my truck suddenly becomes a race car. Well, not really, but in comparison, it feels like it.
Mc2guy said:Now THATS what I am talking about. I have been a huge fan of microturbine technologies given their ability to generate a ton of power at a low weight. Mated to an AC electric drivetrain, now your talking my language. Hopefully in my lifetime
Well this has to be the most of topic tangent ever.
I bought one of the very first 2007 Toyota Tundras and it had a few growing pains. The factory was very interested in real world use and abuse and once I made contact with them over a tail gate problem they spent lots of time in my shop and in the feild testing stuff with me. One Night over dinner I mentioned my interest in a small turbo charged constant speed deisel electric hybrid. They got really quiet and looked at each other. I then went on to include a possible micro turbine and the efficiency as well and ability to burn whatever was availible as fuel. They asked"Who do you know?" I said "nobody but I'm close HUH?" the head engineer said they could not talk about it but GM and Toyota were in a bit of a race.
I wonder what came of it with the GM and Toyota financial problems.
wayne
Kevin
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wasn't that what granatelli drove in a nascar race and had the field covered right before it broke? or was that a rotory engine?carson said:
crosscountry
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Bring out the gloves..
Kevin, I like your location, we have stayed there several times and enjoy watching the barges.
All I know is my ISB 275 hauled my full size Chevy Van (loaded around 6000lb) over the Mt's in El Paso and the Grapevine in Calif on I 5. We did however drop back to 35mph and enjoyed the scenery.
Russ
Kevin, I like your location, we have stayed there several times and enjoy watching the barges.
All I know is my ISB 275 hauled my full size Chevy Van (loaded around 6000lb) over the Mt's in El Paso and the Grapevine in Calif on I 5. We did however drop back to 35mph and enjoyed the scenery.
Russ
SCVJeff
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Wasn't that Indianapolis in the early 60's. The thing was ridiculous fast but they always had trouble keeping it running. Then there was the fuel...kevin said:
taoshum
Well-known member
jrshall said:
Like all the trains today? Diesel electric generators and electric motors??? Who woulda guessed it is the best solution for a train?
John From Detroit
Well-known member
Read the article on the Chrysler Turbo.. Seems the major issues were operator incompatibility (Failure to RTFM)
There is a reason Trains run on D-E power.. (Or Steam) and that is this.
You can run the Diesels up to peak HP, crank out the Volt-Amps like you woudl not believe. and then feed the power to a Serries wound motor (There are 3 different ways to wind an elecric motor that I know of series, shunt and synchronized) A series motor produces a truly amazing amount of torque at very very low speeds. dropping off as the speed increases, (And by he way I just remembered the difference between Torque and HP, will put in this post) Same as a steam engine (Which devlopes peak toruqe at dead stall) This is exactly what a train engine, or for that mater any locomotive type engine (Automotive) needs to do.
The difference
Torque is measured in Foot Pounds. You have have 1,000 foot pounds of torque but if nothing is moving our HP, which is a measure of WORK doable, is zero
HP is Work, that's is force times distance divided by a constant.. To have HP you got to be moving. You can have TORQUE with no motion
To better understand: WHen you put the wrench on the rusted lug nut and it don't move.. You have TORQUE
When it moves: You have HP
There is a reason Trains run on D-E power.. (Or Steam) and that is this.
You can run the Diesels up to peak HP, crank out the Volt-Amps like you woudl not believe. and then feed the power to a Serries wound motor (There are 3 different ways to wind an elecric motor that I know of series, shunt and synchronized) A series motor produces a truly amazing amount of torque at very very low speeds. dropping off as the speed increases, (And by he way I just remembered the difference between Torque and HP, will put in this post) Same as a steam engine (Which devlopes peak toruqe at dead stall) This is exactly what a train engine, or for that mater any locomotive type engine (Automotive) needs to do.
The difference
Torque is measured in Foot Pounds. You have have 1,000 foot pounds of torque but if nothing is moving our HP, which is a measure of WORK doable, is zero
HP is Work, that's is force times distance divided by a constant.. To have HP you got to be moving. You can have TORQUE with no motion
To better understand: WHen you put the wrench on the rusted lug nut and it don't move.. You have TORQUE
When it moves: You have HP
Tom
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All this "torque" about diesel-electric locomotives brings back fond memories of when I worked at a locomotive repair shop. D-E "locos" were used to move stuff around a steel plant, the largest in Europe at that time; Molten pig iron in large ladles from the blast furnaces, steel ingots from the open hearth furnaces and VLN steel making plants, and coiled steel from the output of the hot strip mill and cold rolling mill.
IIRC we had 39 locomotives in the fleet, comprised of two brands - ALCO and Brush. A railroad engineer friend tells me that ALCO is no longer in production.
The electrical side of these beasts was quite straightforward in those days, and I vaguely recall having an entire schematic on a laminated card in my pocket. I don't recall the horsepower produced by those diesel engines, but they were big numbers
IIRC we had 39 locomotives in the fleet, comprised of two brands - ALCO and Brush. A railroad engineer friend tells me that ALCO is no longer in production.
The electrical side of these beasts was quite straightforward in those days, and I vaguely recall having an entire schematic on a laminated card in my pocket. I don't recall the horsepower produced by those diesel engines, but they were big numbers
carson
Well-known member
Thanks John and Tom, brings back memories too...
I my younger years I was proud of my arm wrestling. I thought I had a lot of Torque (ego) but got beat most of the time. Guess I didn't have enoughhorse man power on the way down. Usually lost to guys with shorter forearms. Does that make sense?
carson FL
I my younger years I was proud of my arm wrestling. I thought I had a lot of Torque (ego) but got beat most of the time. Guess I didn't have enough
carson FL
Marc L
Well-known member
Maybe, your long arm was used as leverage for them. (Just a guess).
