Does HP matter?

[Jerry/MT]

If you know the HP and the rpm you can calculate torque.

[MF1433V]

One thing to remember is that acceleration follows the torque curve and I think that is what was meant. You are correct with the common calculation from the strip. They make assumptions on aerodynamics and gear losses etc and now you enter the time element which is the key to HP.

Yes, exactly...thanks for helpful post. If you have an engine that produces a lot of low end torque and the curve stays fairly linear (or increasing) you can get great times without a lot of shifting. If you have a high reving engine with the poor low RPM torque and produces the torque at 5-7K RPM you have to do a lot of shifting to keep in the power band for good 0-60 runs. Launch control and lightened flywheels can help these get to the power band

[MF1433V]

As far as HP mattering, I might as well mention I have Kohler K341 16 HP engines that have tons more torque than the newer 26+ HP gas twin engines being made. The Kohler K series are little torque monsters. But I digress as we all know the HP games some manufactures have played in confusing the ratings for the consumer.

[SPYDERLK]

Do you have that backwards? You can pretty accurately calculate HP from 1/4 mile times, you can't do that to find torque.
Or is that not right? (seriously, I'm not sure!)

YOU are right John. HP will make any torque you want -- just run it thru an appropriate gearbox. It is very difficult to soundbyte this issue because the terms become inseparable as soon as you start talking HP transmitted by rotation. Torque is a static - a force at the end of a leverage arm trying to twist around a pivot. There is no work done until there is motion. As soon as there is motion you have the Force times a Distance that the force at the end of the lever moves. Work is being done. Also, inherent in any motion is its speed - so that D component is truly D per unit time. So with motion attributed you have (F X D)/Time. Thats Foot Pounds per second. Thats HORSEPOWER. The fact that the distance is in a circle doesnt matter.
---- Just imagine that circle is a drum on an engine shaft reeling in a rope with a weight on it. For convenient example make the drum 1' in radius. Its circumference is then 2 Pi feet ~ 6.28 ft. Note that the lever is 1foot so engine torque in ft lbs arrives out at the end of the lever as a force in pounds ... 30 ft-lbs gives you 30lb on the drum rim. If that drum rotates once lifting a 30# weight your engine does 6.28 x 30 ~ 189ftlb of work. What HP? ... Well, how fast did the engine do the work? ... Suppose it was running at 1200rpm - thats 20 rps - therefore it produced 189 x 20 ~ 3800 ftlb/sec. I think the conversion is about 550. Looks like about 7HP.
larry

[MF1433V]

YOU are right John. HP will make any torque you want -- just run it thru an appropriate gearbox. It is very difficult to soundbyte this issue because the terms become inseparable as soon as you start talking HP transmitted by rotation. Torque is a static - a force at the end of a leverage arm trying to twist around a pivot. There is no work done until there is motion. As soon as there is motion you have the Force times a Distance that the force at the end of the lever moves. Work is being done. Also, inherent in any motion is its speed - so that D component is truly D per unit time. So with motion attributed you have (F X D)/Time. Thats Foot Pounds per second. Thats HORSEPOWER. The fact that the distance is in a circle doesnt matter.
---- Just imagine that circle is a drum on an engine shaft reeling in a rope with a weight on it. For convenient example make the drum 1' in radius. Its circumference is then 2 Pi feet ~ 6.28 ft. Note that the lever is 1foot so engine torque in ft lbs arrives out at the end of the lever as a force in pounds ... 30 ft-lbs gives you 30lb on the drum rim. If that drum rotates once lifting a 30# weight your engine does 6.28 x 30 ~ 189ftlb of work. What HP? ... Well, how fast did the engine do the work? ... Suppose it was running at 1200rpm - thats 20 rps - therefore it produced 189 x 20 ~ 3800 ftlb/sec. I think the conversion is about 550. Looks like about 7HP.
larry

I don't even know what to day here, I'm just too tired to get into the the difference between the actual physics and calculations (some erroneous).
But this does have to be addressed "HP will make any torque you want -- just run it thru an appropriate gearbox" I think someone already mentioned that torque is the amount of twisting force and engine can produce. Gearing cannot produce torque but can multiple the torque the engine puts out. HP is a calculation and cannot make torque.
Oh what the **** one more "Torque is static" Torque can be static, but in an engine it is not. There is no torque produced until the engine is running. The torque is produced by the engine transferred to the transmission, to the wheels and to the ground. An example of static torque is the torque of a nut and bolt.

I didn't read the 2nd paragraph so not sure there.

[SPYDERLK]

YOU are right John. HP will make any torque you want -- just run it thru an appropriate gearbox. It is very difficult to soundbyte this issue because the terms become inseparable as soon as you start talking HP transmitted by rotation. Torque is a static - a force at the end of a leverage arm trying to twist around a pivot. There is no work done until there is motion. As soon as there is motion you have the Force times a Distance that the force at the end of the lever moves. Work is being done. Also, inherent in any motion is its speed - so that D component is truly D per unit time. So with motion attributed you have (F X D)/Time. Thats Foot Pounds per second. Thats HORSEPOWER. The fact that the distance is in a circle doesnt matter.
---- Just imagine that circle is a drum on an engine shaft reeling in a rope with a weight on it. For convenient example make the drum 1' in radius. Its circumference is then 2 Pi feet ~ 6.28 ft. Note that the lever is 1foot so engine torque in ft lbs arrives out at the end of the lever as a force in pounds ... 30 ft-lbs gives you 30lb on the drum rim. If that drum rotates once lifting a 30# weight your engine does 6.28 x 30 ~ 189ftlb of work. What HP? ... Well, how fast did the engine do the work? ... Suppose it was running at 1200rpm - thats 20 rps - therefore it produced 189 x 20 ~ 3800 ftlb/sec. I think the conversion is about 550. Looks like about 7HP.
larry

I don't even know what to day here, I'm just too tired to get into the the difference between the actual physics and calculations (some erroneous).
But this does have to be addressed "HP will make any torque you want -- just run it thru an appropriate gearbox" I think someone already mentioned that torque is the amount of twisting force and engine can produce. Gearing cannot produce torque but can multiple the torque the engine puts out. HP is a calculation and cannot make torque.
Oh what the **** one more "Torque is static" Torque can be static, but in an engine it is not. There is no torque produced until the engine is running. The torque is produced by the engine transferred to the transmission, to the wheels and to the ground. An example of static torque is the torque of a nut and bolt.

I didn't read the 2nd paragraph so not sure there.

There is nothing erroneous. The problem thruout is in trying to separate torque from HP in a non rigorous fashion. Torque is nothing but a result of leverage. When it overcomes a resistance, causing movement, doing work, it immediately becomes HP. In your example, if the nut turns its HP. [I tried to describe that. ... Do you have a question?]
larry

[LD1]

I am not sure why this is hard for some to understand.

HP is a number that cannot actually be measured. In is simply a calculation based off of torque AND time.

Think of it this way, HP is simply the rate (speed) at which torque can be applied. Therefor HP remains constant. It cannot be increased or decreased (except for frictional losses). Torque CAN be changed with simple gearboxes.

If you can DOUBLE the torque and cut the speed IN HALF with a simple 2:1 gearbox. But the output HP is the SAME, even though the torque changed. Because again, HP is the rate in which the torque can be applied. So you are applying 2x's the torque, but it is taking twice as long.

You can have two motors that are capable of making the same amount of torque, but one can apply it faster, thus has more HP.

Using a drum and cable example, (a winch): it the engines have the same torque, the amout they can pull is going to be the same. BUT, if one of the driving engines has more HP, it can spool up the cable FASTER. But it cannot pull any more if the torque is the same.

[DarkBlack]

I'm glad I deleted my post from yesterday, as I think I was only drawn into a childish battle with an un-armed opponent.
Good to see, at least someone read my post while it was up, and took something away from it.

[MF1433V]

I'm glad I deleted my post from yesterday, as I think I was only drawn into a childish battle with an un-armed opponent.
Good to see, at least someone read my post while it was up, and took something away from it.

So far I would have to agree with LD1 on the troll thing. All you've done is call him out and then you say you posted the support of your views and then deleted it. So thus far you have added nothing but friction.

Now I happen to disagree with a couple of opinions in this thread but I try to explain why and so does the person who disagrees with me. I can respect that. You really should do the same and if you have information to help the thread, wouldn't that be something you would do. If you disagree with anything I have posted and if I am in error with my understanding, please enlighten us and share the higher intelligence you seem to be boasting of. It's only fair to offer an alternative notion.

[SPYDERLK]

I'm glad I deleted my post from yesterday, as I think I was only drawn into a childish battle with an un-armed opponent.
Good to see, at least someone read my post while it was up, and took something away from it.

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