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torque and power 

 

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Posted: Mon Jul 25, 2005 8:24 pm 
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READ THE POST

the empisis is on torque because power is made from torque.

torque does not drop of as rpm rises exept in an electric motor. If you have a look at a dyno for 'most' engines the torque will continue to rise with rpm untill the engine is not longer breathing properly. This is where cams, induction length, variable intake manifold, extractors ect all come into play to decide the torque band which decides the power band.
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 Post subject: Re: way to much torque
Posted: Mon Jul 25, 2005 8:35 pm 
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FPV_GTp wrote:
stockstandard wrote:
One other interesting point that can be made about drag racing...

Notice how in my post above when the physics teacher said that torque is good for the start of a 1/4 and power is good for the rest, he added that this assumes the tires were hooking up. By saying this he avoided some of the other complexities of drag racing.

A 1/4 mile pass can be broken down into two parts - the traction limited part at the start, and the power limited portion that follows. In my car for example, I cant apply all the engines torque of the line because I will just spin the wheels and go nowhere - I am traction limited. If I further increase low end torque without increasing traction, I will go no faster because I will have to use less throttle so I get off the line cleanly.

Instead, if I leave the engine alone and increase traction with some fatter rubber or an LSD, I can reduce the traction limited portion of my 1/4 run, and my ET will drop.

Its all pretty obvious when you think about it, but it helps you picture how all the parts of the car have to work together to get you down the end fast.


hi

just thought i would throw my two bobs worth in this convo

sorry if i missed something earlier cause i havent read the whole posting

but the the emphasis is all on torque ??????

remember one thing torque drops of as engine speed (RPM ) increase ??? WHY :wink: ???

now my little question since we on about drag racing and so forth is
do u change gears down the quarter mile at max torque ??? or do you change gears at max horsepower??? and when your in top gear what should you be crossing the line at max torque or max horsepower ???


just my few questions and im sure someone from St Albans can answer the question PMSFL :wink:

cya


Its all about power. Go back and read it some more (or at lest from page 5 onwards).

 

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 Post subject: LOL
Posted: Mon Jul 25, 2005 8:36 pm 
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Blu Falc wrote:
READ THE POST

the empisis is on torque because power is made from torque.

torque does not drop of as rpm rises exept in an electric motor. If you have a look at a dyno for 'most' engines the torque will continue to rise with rpm untill the engine is not longer breathing properly. This is where cams, induction length, variable intake manifold, extractors ect all come into play to decide the torque band which decides the power band.



LOL

mmmmmmmmm maybe i should read the post hahahaha
lol torque does drop of maybe you should have a look at some dyno graphs LOL :wink: you answered one of the question i asked but the rest i think you have it wrong LOL, at higher rpm cylinder fill starts to diminish so torque does drop of LOL

cya

 

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Last edited by FPV_GTp on Mon Jul 25, 2005 8:40 pm, edited 1 time in total.

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 Post subject: Re: way to much torque
Posted: Mon Jul 25, 2005 8:38 pm 
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stockstandard wrote:
FPV_GTp wrote:
stockstandard wrote:
One other interesting point that can be made about drag racing...

Notice how in my post above when the physics teacher said that torque is good for the start of a 1/4 and power is good for the rest, he added that this assumes the tires were hooking up. By saying this he avoided some of the other complexities of drag racing.

A 1/4 mile pass can be broken down into two parts - the traction limited part at the start, and the power limited portion that follows. In my car for example, I cant apply all the engines torque of the line because I will just spin the wheels and go nowhere - I am traction limited. If I further increase low end torque without increasing traction, I will go no faster because I will have to use less throttle so I get off the line cleanly.

Instead, if I leave the engine alone and increase traction with some fatter rubber or an LSD, I can reduce the traction limited portion of my 1/4 run, and my ET will drop.

Its all pretty obvious when you think about it, but it helps you picture how all the parts of the car have to work together to get you down the end fast.


hi

just thought i would throw my two bobs worth in this convo

sorry if i missed something earlier cause i havent read the whole posting

but the the emphasis is all on torque ??????

remember one thing torque drops of as engine speed (RPM ) increase ??? WHY :wink: ???

now my little question since we on about drag racing and so forth is
do u change gears down the quarter mile at max torque ??? or do you change gears at max horsepower??? and when your in top gear what should you be crossing the line at max torque or max horsepower ???


just my few questions and im sure someone from St Albans can answer the question PMSFL :wink:

cya


Its all about power. Go back and read it some more (or at lest from page 5 onwards).



LOL


i have read it all :wink: LOL

and i know where my money s on LOL POWER for the people :wink:

cya

 

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Posted: Mon Jul 25, 2005 8:42 pm 
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torque drops off (slowly) with rpm.

Mine makes about
310nm @ 3600
301nm @ 4000
276nm @ 5000
...

 

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 Post subject: thank u
Posted: Mon Jul 25, 2005 8:47 pm 
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stockstandard wrote:
torque drops off (slowly) with rpm.

Mine makes about
310nm @ 3600
301nm @ 4000
276nm @ 5000
...



thank you :wink: now do you have the Bhp figures saves me not having to calculate them and do you have figures for T,RPM,Bhp for higher rpm just to see what happens at higher up

now im going way of track here :wink:

what motor produces max torque at nearly zero revs?????

cya

 

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Last edited by FPV_GTp on Mon Jul 25, 2005 8:51 pm, edited 2 times in total.

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 Post subject: Re: thank u
Posted: Mon Jul 25, 2005 8:50 pm 
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FPV_GTp wrote:
stockstandard wrote:
torque drops off (slowly) with rpm.

Mine makes about
310nm @ 3600
301nm @ 4000
276nm @ 5000
...



thank you :wink: now do you have the Bhp figures saves me not having to calculate them and do you have figures for T,RPM,Bhp for higher rpm just to see what happens at higher up

now im going way of track here :wink:

what motor produces max torque at nearly at zero revs?????

cya


An electric motor!
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 Post subject: Re: LOL
Posted: Mon Jul 25, 2005 9:23 pm 
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FPV_GTp wrote:
LOL

mmmmmmmmm maybe i should read the post hahahaha
lol torque does drop of maybe you should have a look at some dyno graphs LOL :wink: you answered one of the question i asked but the rest i think you have it wrong LOL, at higher rpm cylinder fill starts to diminish so torque does drop of LOL

cya


Your statement clearly states that torque is maximum @ zero revs. You say that torque decreases with rpm? If that's so, and torque ALWAYS gets lower with an increase in RPM, how does it RISE to PEAK torque in the first place?

It would be more correct to say that cylinder fill drops off after peak torque is achieved and even then, that's not completely true.

There are plently of engines out there with two peak torque figures because of the cam and intake characteristics. So on these engines, torque drops off with rpm after the first peak torque, then starts to rise, shock horror, till it hits the second peak torque figure.

I can't believe that so many people are incapable of understanding stockstandard's initial post.

I can see there are a lot of people here whom I would not be at all surprised to see driving a car with either a 2.9 diff and 4000-7000 RPM cam, or a 3.9 diff and a 1000-3000 rpm cam
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Posted: Mon Jul 25, 2005 10:59 pm 
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I don't profess to know much about HP v Torque but there are still a few unanswered questions.
Power = work done in a given time
To do the same amount of work in less time you need more POWER
To make more power given an amount of torque you have to increase the revs, OR at a specific RPM you have to increase the torque available, regardless of engine characteristics.

In Waggins Real world example He probbably spun the wheels a bit more off the line with the XR8 and the aerodynamics probably slowed the I6 at the finish.

 

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 Post subject: Re: way to much torque
Posted: Tue Jul 26, 2005 12:17 am 
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[quote="FPV_GTp]

now my little question since we on about drag racing and so forth is
do u change gears down the quarter mile at max torque ??? or do you change gears at max horsepower??? and when your in top gear what should you be crossing the line at max torque or max horsepower ???
cya[/quote]

Ideally you would change gears at max power. And have the gearing set so that when you change gears the revs fall to the peak torque rpm. That is the quickest way to accelerate.
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 Post subject: Re: LOL
Posted: Tue Jul 26, 2005 12:21 am 
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FPV_GTp wrote:
Blu Falc wrote:
READ THE POST

the empisis is on torque because power is made from torque.

torque does not drop of as rpm rises exept in an electric motor. If you have a look at a dyno for 'most' engines the torque will continue to rise with rpm untill the engine is not longer breathing properly. This is where cams, induction length, variable intake manifold, extractors ect all come into play to decide the torque band which decides the power band.



LOL

mmmmmmmmm maybe i should read the post hahahaha
lol torque does drop of maybe you should have a look at some dyno graphs LOL :wink: you answered one of the question i asked but the rest i think you have it wrong LOL, at higher rpm cylinder fill starts to diminish so torque does drop of LOL

cya




I have seen many dyno graphs, the torque builds then drops off after the engine is being restricted for whatever reason ie it has passed the efficiency of the cam or the intake is creating restriction ect.
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 Post subject: max torque @ nearly zero revs
Posted: Tue Jul 26, 2005 2:38 am 
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unclewoja wrote:
FPV_GTp wrote:
LOL

mmmmmmmmm maybe i should read the post hahahaha
lol torque does drop of maybe you should have a look at some dyno graphs LOL :wink: you answered one of the question i asked but the rest i think you have it wrong LOL, at higher rpm cylinder fill starts to diminish so torque does drop of LOL

cya


Your statement clearly states that torque is maximum @ zero revs. You say that torque decreases with rpm? If that's so, and torque ALWAYS gets lower with an increase in RPM, how does it RISE to PEAK torque in the first place?

It would be more correct to say that cylinder fill drops off after peak torque is achieved and even then, that's not completely true.

There are plently of engines out there with two peak torque figures because of the cam and intake characteristics. So on these engines, torque drops off with rpm after the first peak torque, then starts to rise, shock horror, till it hits the second peak torque figure.

I can't believe that so many people are incapable of understanding stockstandard's initial post.

I can see there are a lot of people here whom I would not be at all surprised to see driving a car with either a 2.9 diff and 4000-7000 RPM cam, or a 3.9 diff and a 1000-3000 rpm cam



lol


read what i wrote

yes max torque @ nearly zero revs steam engine

i just throw this into the convo just a brain teaser

but never mind i think you saying im contradicting myself :wink:

on a internal combution engine cylinder fill does fall of at higher :wink:
RPM :wink:

cya

 

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Posted: Tue Jul 26, 2005 10:41 pm 
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a cam can make the engine fill increase with rpm up to a certain point by having long duration and lift and uses the inertia of the intake air and fuel to keep filling the cylinder even when the piston is moving up, obviously not too far up.
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