torque or horsepower

[tom d]

digger, think about it. horsepower is based on the amount of work that a horse can do and that is subjective, the number has been changed several times over the course of history, not so with torque. horsepower is a made up term, there is no way to measure it scientifically.

[tom d]

so you measure torque "scientifically" and you measure rpm "scientifically" and anything done with those two bits of data suddenly becomes nonsense....right what were you saying about ridiculous?

you're right, both torque and revolutions per minutes can be measured, but to say that multiplying one by the other and then dividing the two by a number that is based on the ratio of what a horse can do compared to how far a foot pound travels around a pivot does not make it a real scientific fact.

that would be like saying peanut butter and jelly makes one good sandwich, so ham on rye must be 5.5 good sandwiches.

[digger]

you're right, both torque and revolutions per minutes can be measured, but to say that multiplying one by the other and then dividing the two by a number that is based on the ratio of what a horse can do compared to how far a foot pound travels around a pivot does not make it a real scientific fact.

that would be like saying peanut butter and jelly makes one good sandwich, so ham on rye must be 5.5 good sandwiches.

kW is also a unit of power and not based on horses does that help you?

please stop posting your logic is embarrassing and your arguments are weak

[tom d]

really? explain to me in scientific terms how you can measure horsepower and how that measurement comes to equals 33,000lb-ft./min.

James Watts invented the term so that he could sell steam engines. Naturally, Mr. Watt wanted to tell everybody how powerful his engines were. So, after some tests (not with engines but with horses) he established that on the average, a horse could haul coal at the rate of 22,000 lb-ft per min. For some reason he decided the raise this number by 50% to arrive at 33,000 lb-ft per minutes. So, if an engine can push 33,000 Lb of something one foot in one minute, we say that is a one-horsepower engine.

so you see horsepower is based on a completely arbitrary number and has nothing to do with how much work a horse can really do. your point continues to be that horsepower is more relevant to the performance of a motor then it's torque, but in reality you can not calculate the horsepower of a motor without first measuring it's torque, but you can certainly measure a motor's torque without ever calculating its horsepower. that fact alone makes torque king of this debate.

now from a practical standpoint torque is always better to have. it's torque that gets your car moving, it's torque that hauls it up the hill, it's torque that we drive on a daily basis. how many people do you know that drive thier M20's at 6000 rpms? none!

the only reason the term horsepower is relevant at all is so that we can compare different power plants to each other and think we know what we're talking about, that and having these silly debates.

[Hooffenstein HD]

how many people do you know that drive thier M20's at 6000 rpms? none!

Me. I drive around in second bouncing off the limiter all day everyday.

[mr2peak]

Me. I drive around in second bouncing off the limiter all day everyday.

The only way to drive haha

[digger]

really? explain to me in scientific terms how you can measure horsepower and how that measurement comes to equals 33,000lb-ft./min.

James Watts invented the term so that he could sell steam engines. Naturally, Mr. Watt wanted to tell everybody how powerful his engines were. So, after some tests (not with engines but with horses) he established that on the average, a horse could haul coal at the rate of 22,000 lb-ft per min. For some reason he decided the raise this number by 50% to arrive at 33,000 lb-ft per minutes. So, if an engine can push 33,000 Lb of something one foot in one minute, we say that is a one-horsepower engine.

so you see horsepower is based on a completely arbitrary number and has nothing to do with how much work a horse can really do. your point continues to be that horsepower is more relevant to the performance of a motor then it's torque, but in reality you can not calculate the horsepower of a motor without first measuring it's torque, but you can certainly measure a motor's torque without ever calculating its horsepower. that fact alone makes torque king of this debate.

now from a practical standpoint torque is always better to have. it's torque that gets your car moving, it's torque that hauls it up the hill, it's torque that we drive on a daily basis. how many people do you know that drive thier M20's at 6000 rpms? none!

the only reason the term horsepower is relevant at all is so that we can compare different power plants to each other and think we know what we're talking about, that and having these silly debates.

blah blah blah........prove it with an example

hp is a concept that is useful for those that understand physics and vehicle dynamics. whether you directly measure it or not doesn't change the fact those it is extremely useful comparison tool.

the more hp you have at the wheels the more torque you potentially have in the axles which is all that matters. engine torque magnitude is extremely misleading the shape of the torque curve is useful though.

the E60M5 was just as fast as the e55 of the same era with a massive deficit of engine torque because the hp and mass was about the same. this works becasue you can use more aggressive gearing and more gears in total to provide performance through torque mulitplication

[henryki]

This thread.

wow. such butthurt. much scientists. so power. wow.

[tom d]

here's another reason why using the unit horsepower is dumb when talking about motors.

energy which is power multiplied by time can be measured in units of horsepower, watts, or btu's per hour. one horsepower is equal to 746 watts and 746 watts is equal to 2545 BTUs/hr.

so if you had a 1000 watt lightbulb and you lite it for 1hour the lightbulb would have the engery of 1000watts, 2545 BTUs/hr or 1.34 horsepower. knowing this you can now impress your friends by telling them that your 165 horsepower engine is just as powerful as 1231 - 100 watt lightbulbs, that should do the trick!

[tom d]

the more hp you have at the wheels the more torque you potentially have in the axles which is all that matters. engine torque magnitude is extremely misleading the shape of the torque curve is useful though.

digger, would you care to explain in laymen's terms WTF this means, because all I get from it is psychobabble.

[digger]

here's another reason why using the unit horsepower is dumb when talking about motors.

energy which is power multiplied by time can be measured in units of horsepower, watts, or btu's per hour. one horsepower is equal to 746 watts and 746 watts is equal to 2545 BTUs/hr.

so if you had a 1000 watt lightbulb and you lite it for 1hour the lightbulb would have the engery of 1000watts, 2545 BTUs/hr or 1.34 horsepower. knowing this you can now impress your friends by telling them that your 165 horsepower engine is just as powerful as 1231 - 100 watt lightbulbs, that should do the trick!

nope watt is power, so its 1000w of power (not energy of 1000W) but energy is power x time = 1000W x 3600s = 3600kJ

the electricity used to power a 1000W bulb could be used to power an electric motor that has 1000W which would be the same as a 1000W Internal combustion engine

[digger]

digger, would you care to explain in laymen's terms WTF this means, because all I get from it is psychobabble.

i doubt it is worth my time discussing this anymore sorry

[reelizmpro]

I have had this debate many times and while torque is what you feel and what moves the car...HP is what makes it useful because it represents torque x rpm. Rpm is critical here because it is the number of revolutions over time. Torque by itself is meaningless when it comes to how powerful an engine is. In contrast, higher rpm's can get more power to the wheels through shorter gearing. Now the debate goes on and on because people who are pro-torque are actually talking about HP. There's a reason we use it to rate engines.

Look at our cars..

Eta engine has 170 ft/lbs torque but only 121hp @4200 rpms 2.79 or 2.93 final drive.
325I engine has 165ft/lbs torque but 168hp @5800 rpms 3.73 final drive.

We know the 325i is faster than the eta because the 325I is getting more power to the wheels. It's area under the curve is actually greater than the eta even though it has more torque because the eta cannot rev past 5000 rpm while the 325I still has a couple thousand rpm's to play with. In layman's terms the eta is fast off the line but it can't sustain it over time. If you put a 3.73 in the eta, it will be faster upto a point but it will run out of rpm's faster and it's top speed will be limited.

This is why 1.6 liter Honda engines can be fast in a sprint. They can make good HP and put it down through very short gearing. Cars like the s2000, e30 m3, itr all have similar traits...high hp/rpms from small displacement. This is the basis for road race engines. Few people like peaky cars on the street though so for stoplight racing most prefer to have more low end torque.

Here's a good link that explains things better.

http://www.houseofthud.com/cartech/torqueversushorsepower.htm

Here's a quote: "Maximum acceleration of a car is made possible by maximizing your output
torque at the wheels at ALL times."

So we see that torque at the wheels is what moves the car sure but "at ALL times?"...now we are actually talking about HP as defined by (Torque x RPM) / 5252. In cars with transmissions and final drives, gearing is always a factor. Raise the RPM, you raise the HP regardless of engine torque...then through gearing you can get max torque to the ground throughout the RPM range. The problem with torque is that it is just a force without time and isn't really useful in describing the performance of an engine by itself.

[tom d]

digger, would you care to explain in laymen's terms WTF this means, because all I get from it is psychobabble.

i doubt it is worth my time discussing this anymore sorry

because you can't!

[ForcedFirebird]

because you can't!

Instead of trying to argue, why don't you read the thread and links? Horsepower has nothing to do with comparing a horse to what an engine can do, and definitely is not subjective as it's based on actual data.

1 hp = the ability to move 550lbs 1ft in 1sec (33,000lb in one minute). Forget that it's called "horsepower", it's the ability to move an object xx to xx in xx amount of time. Since we do not have an accurate way to measure this (specially if the vehicle/engine is stationary), we can measure rotational torque on a dyno, and it is calculated as such.