| Re: Torque vs. HP explained in 90 seconds | <– Date –> <– Thread –> |
From: Rick Moseley (ramosel pacbell.net)
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| Date: Fri, 6 Mar 2015 08:32:44 -0800 (PST) | |
Peter,
Horsepower and torque are moments of a common vector when time is applied. While your equations are perhaps applicable to "a" motor those equations do no apply to "all" motors. Think about it, most diesels won't even do 5252 rpm. And one of the cars in the video was electric and while it too has components called torque and horsepower which can be measured on the same scales it's graphs are COMPLETELY different. A gas motor has ZERO torque at ZERO RPM. An electric motor has MAXIMUM TORQUE at ZERO RPM. Horsepower and torque are intertwined deeply in one another. They are dependent on one another. They are NOT the same thing. Torque is a measurable unit of rotational force, Horsepower is generally a linear force in a period of time (Watt rated it as how much force "a" horse would exert to lift 33000 lbs one foot in one minute). One, not the only, definition of HP is it's toque moment over time. (Thus I think Mert's use of the word "sustains")
torque = ft-lb (static)
1hp = 33000 ft-lb/min (dynamic - time)
So torque and HP can not be the same thing as torque is a component of HP without time applied. related, dependent, yes. Same, no.
As I said, that is ONE value for HP, not the ONLY value. It is also 746 watts. So in the case of a bike rider or an electric motor, it is also a rotational force, in the case of a light-bulb, not! No rotational force. There is also Boiler HP which has to do with the evaporation of a given quantity of water at sea level. Again, no rotational force. And we won't even go into how the Brits calculate RAC taxable HP on the basis of bore and number of cylinders.
Does that help separate torque and HP from being the same thing? I tried.
Rick
Horsepower and torque are moments of a common vector when time is applied. While your equations are perhaps applicable to "a" motor those equations do no apply to "all" motors. Think about it, most diesels won't even do 5252 rpm. And one of the cars in the video was electric and while it too has components called torque and horsepower which can be measured on the same scales it's graphs are COMPLETELY different. A gas motor has ZERO torque at ZERO RPM. An electric motor has MAXIMUM TORQUE at ZERO RPM. Horsepower and torque are intertwined deeply in one another. They are dependent on one another. They are NOT the same thing. Torque is a measurable unit of rotational force, Horsepower is generally a linear force in a period of time (Watt rated it as how much force "a" horse would exert to lift 33000 lbs one foot in one minute). One, not the only, definition of HP is it's toque moment over time. (Thus I think Mert's use of the word "sustains")
torque = ft-lb (static)
1hp = 33000 ft-lb/min (dynamic - time)
So torque and HP can not be the same thing as torque is a component of HP without time applied. related, dependent, yes. Same, no.
As I said, that is ONE value for HP, not the ONLY value. It is also 746 watts. So in the case of a bike rider or an electric motor, it is also a rotational force, in the case of a light-bulb, not! No rotational force. There is also Boiler HP which has to do with the evaporation of a given quantity of water at sea level. Again, no rotational force. And we won't even go into how the Brits calculate RAC taxable HP on the basis of bore and number of cylinders.
Does that help separate torque and HP from being the same thing? I tried.
Rick
Hi Larry,
I understand what you’re saying, but I can’t get past the fact that you could still quote a HP figure @ xxxxrpm and use a multiplier to get torque and vice versa. It still means that they’re fundamentally the same thing. If you have more HP at certain revs, you have more torque. If you have more torque at certain revs, you have more HP. Seems too interchangeable to me to see how it’s really different. I’m sure I’m missing something (a brain?)….but I don’t get it.
From: Ferrari [mailto:ferrari-bounces+ferrarilist=pless.com.au [at] ferrarilist.com] On Behalf Of LarryT
Sent: Saturday, 7 March 2015 12:38 AM
To: Peter Pless
Cc: The FerrariList
Subject: Re: [Ferrari] Torque vs. HP explained in 90 seconds
Sent: Saturday, 7 March 2015 12:38 AM
To: Peter Pless
Cc: The FerrariList
Subject: Re: [Ferrari] Torque vs. HP explained in 90 seconds
Hi Peter,
I think I understand what you are saying but I disagree. Some engines have high torque early and low HP. Especially diesels are in this category - while gas engines have higher HP and torque that builds over time. Looking at graphs that show the torque curve and Hp curve have a place where the curves cross - to me that's very close to the ""Sweet Spot" where a car can be driven and it feels like it can drive forever at that speed.
Then there's electric motors that have full torque from 0 rpm's.
I think it's important to think of Torque and Horsepower in a Time context. Maybe like this - HP is the amount of work a engine can do and Torque is the Time it takes to do that work.
Does that make any sense?
LarryT
I think I understand what you are saying but I disagree. Some engines have high torque early and low HP. Especially diesels are in this category - while gas engines have higher HP and torque that builds over time. Looking at graphs that show the torque curve and Hp curve have a place where the curves cross - to me that's very close to the ""Sweet Spot" where a car can be driven and it feels like it can drive forever at that speed.
Then there's electric motors that have full torque from 0 rpm's.
I think it's important to think of Torque and Horsepower in a Time context. Maybe like this - HP is the amount of work a engine can do and Torque is the Time it takes to do that work.
Does that make any sense?
LarryT
On 3/5/2015 9:19 PM, Peter Pless wrote:
Torque and HP are more or less the same thing, aren’t they? It’s just that instead of saying a car has 115hp at 3000rpm you can say it has 200ft/lb at 3000rpm.T = HP * 5252 / RPM
HP = T * RPM / 5252
RPM = HP * 5252 / TDoes that mean torque another terminology for HP and vice versa? A higher torque number at lower revs is higher HP and lower revs..same same.People talk like the two are mutually exclusive.From: Ferrari [mailto:ferrari-bounces+ferrarilist=pless.com.au [at] ferrarilist.com] On Behalf Of Rick Moseley
Sent: Friday, 6 March 2015 1:05 PM
To: Peter Pless
Cc: The FerrariList
Subject: Re: [Ferrari] Torque vs. HP explained in 90 secondsTrue, in the strange world of motion physics both statements work. They are not mutually exclusive. Both elements are dependent on the other. And yet can be measured independently.
On Mar 5, 2015, at 5:55 PM, Pat Scopelliti <pscopell [at] stny.rr.com> wrote:I always heard it as torque determines acceleration, but horsepower determines top speedPatPat ScopellitiFrom: Ferrari [mailto:ferrari-bounces+pscopell=stny.rr.com [at] ferrarilist.com] On Behalf Of Rick Moseley
Sent: Thursday, March 05, 2015 7:38 PM
To: Pat Scopelliti
Cc: The FerrariList
Subject: Re: [Ferrari] Torque vs. HP explained in 90 secondsYou got it... It's subtle, but there is a difference between quick and fast.
Rick
On Mar 5, 2015, at 4:30 PM, Fellippe Galletta <fellippe.galletta [at] gmail.com> wrote:Rick,I agree with the quote....it's definitely true.It also explains why a car with a torque monster motor often feels faster than a car with a peakier motor that's actually faster.FGOn Thu, Mar 5, 2015 at 7:11 PM, Rick Moseley <ramosel [at] pacbell.net> wrote:Great presentation on how an electric motor delivers maximum torque at 0 (zero) RPM.I had the privilege of working a few weeks in Ed Pink's shop one summer during High School (a favor to my older brother). One Friday evening a few legendary drag racers showed up. So I asked them to explain the relation between HP and Torque. Mert Littlefield gave me the best and shortest answer I've ever heard.Torque provides acceleration, Horsepower sustains torque.I have a few friends today who are on the top rung of race motor engineering and when I repeat Mert's quote... They scratch their heads, think about it a bit and reluctantly say "yup". They all say there is more to it... but it takes a lot more words to say the same thing in engineering speak. Just about everyone has written it down... The one who didn't I know has a photographic memory.Rick
On Mar 5, 2015, at 3:08 PM, Fellippe Galletta <fellippe.galletta [at] gmail.com> wrote:Enjoy,FGps - The guy running the F12 said he averaged a 10.8 @ 132_________________________________________________________________
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- Re: Torque vs. HP explained in 90 seconds, (continued)
- Re: Torque vs. HP explained in 90 seconds LarryT, March 6 2015
- Re: Torque vs. HP explained in 90 seconds Fellippe Galletta, March 6 2015
- Re: Torque vs. HP explained in 90 seconds Peter Pless, March 6 2015
- Re: Torque vs. HP explained in 90 seconds Charles Perry, March 6 2015
- Message not available
- Re: Torque vs. HP explained in 90 seconds Rick Moseley, March 6 2015
- Re: Torque vs. HP explained in 90 seconds Peter Pless, March 6 2015
- Re: Torque vs. HP explained in 90 seconds Jim Conforti, March 6 2015
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