Ferrari Mailing List: Re: Torque vs. HP explained in 90 seconds

[Charles Perry (charles]

Peter –

 

You’re on the right track. What I think you’re missing is the RPM factor. That is where motors can differ dramatically and what ends up defining their HP versus Torque relationship.

 

A motor like a truck diesel typically has big, heavy-duty internals and high engine displacement. Those internals can’t change direction very quickly due to their mass. So while a truck motor may make huge torque, it usually doesn’t make good horsepower because its redline will always be low due to the reciprocating mass of its internals. Plug that low RPM into the formula you’re toying with and you’ll see the relationship.

 

Contrast that with a Ferrari motor, where things like hollow valves and titanium connecting rods minimize the weight of the internals. They can therefore change direction very quickly, translating to a very high redline. Ferrari motors don’t typically make a lot of torque due to their small displacement, but they do turn a lot of RPM, so they turn what little torque they have into good horsepower figures.

 

Forced induction can shift these curves around a lot because you can make more torque with smaller displacement, and therefore can also build more RPM and thus more horsepower. Lots of ways to tune from there…

 

-- charles

 

From: Ferrari [mailto:ferrari-bounces+charles=carolina-sound.com [at] ferrarilist.com] On Behalf Of Peter Pless
Sent: Friday, March 06, 2015 8:53 AM
To: Charles Perry
Cc: 'The FerrariList'
Subject: Re: [Ferrari] Torque vs. HP explained in 90 seconds

 

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

 

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

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 / T

 

http://www.metaris.com/hp-relations.php

 

Does 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 seconds

 

True, 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 speed

 

Pat

 

Pat Scopelliti

pscopell [at] stny.rr.com

From: 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 seconds

 

You 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. 

 

FG

 

On 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,

 

https://www.youtube.com/watch?v=_nQDU7HOStc

 

FG

 

ps - The guy running the F12 said he averaged a 10.8 @ 132

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