Torque vs power

[jc denton]

Loads of torque or loads of power?

 

[MasterAuron]

Both

 

[turbonutter69]

+1

Both

 

[Zwaf]

Horse Power=RPM x Nm / 7024 (i think this is correct math, but who knows?)

You can have lot of power without lot of torque only if make dramatic increase in RPM - like in F1 or most motorcicle engines.
A lot of torque is pure fun! (saiz the diesel driver )
Ideally we could use both, but if I must choose I'll keep the torque for everyday road car, and power that comes from high revs for track.
I guess it is "duce" in tenis terms.

 

[HDi fun]

Power is just a function of revs and torque. I suppose ideally we'd like to have 500lbft all the way from idle speed right to a nice high 7500-8000rpm red line.

In generally agree that for everyday driving large slugs of torque at low revs makes for effortless performance. I used to drive a 406 HDi 2.2 remapped to deliver about 320lb/ft.

Diesel engines are getting better at the rev thing nowadays, even my 2001 example would pull strongly to about 5300rpm. This is high in the diesel world.

But with manufacturers now pumping money into petrol engines again that could all be set to change.

 

[jc denton]

Nobody understands (stands-under) those kinds of persistently overly scientific explinations on such matters pertaining to that which is at hand...Just vote.

 

[MasterAuron]

Why do I need to vote? I have fairly equal amounts of both, you don't need to choose.

 

[Zwaf]

Nobody understands (stands-under) those kinds of persistently overly scientific explinations on such matters pertaining to that which is at hand...Just vote.

Torque is power! Nothing to vote!
Your stereo got power but does not move around - it have no torque!

 

[MasterAuron]

True but at the same rpm. I take it he means would you rather have higher peak torque (usually lower down) or higher peak power (usually higher up).

 

[Zwaf]

Hi MasterAuron!
I know what is meanted in this poll. My post is just for educational purpose. In other hand I have wrote what would I choose considering circumstances of use.

For everyday more torque, for track (or illegal blasting) more revs.
If not aloud to give dual answer then torque all the way for me.

 

[dannemare]

Nobody understands (stands-under) those kinds of persistently overly scientific explinations on such matters pertaining to that which is at hand...Just vote.

Well, I'm not gonna vote as the poll really doesn't make sense as torque and power are bound together by the same math formula. Power is simply a product of torque and revs. Never try to separate them.

Just to make it clear to everybody: If you gain torque at a specific rpm, you gain hp at that rpm as well, and if you lose torque at a specific rpm, you lose lose hp at that rpm as well.

More torque means more power, at any given rpm.
Less torque means less power, at any given rpm.

For outright performance, high-rpm torque is what matters since your needle will simple stay in the upper rev range the whole time as you hunt redline in every gear, so low-end meaty torque is, in this respect, completely useless. Peak power is a much better performance indicator than peak torque.

Of course, the exception to the rule of hunting your redline for maximum acceleration would be if your torque goes down the toilet way before redline (which indicates a crappy tune that doesn't take advantage of gearing).

Bottom line: For the performance enthusiast it is always better to produce high torque at high rpm rather than high torque at low rpm.

 

[jc denton]

Well, I'm not gonna vote as the poll really doesn't make sense as torque and power are bound together by the same math formula. Power is simply a product of torque and revs. Never try to separate them.

Just to make it clear to everybody: If you gain torque at a specific rpm, you gain hp at that rpm as well, and if you lose torque at a specific rpm, you lose lose hp at that rpm as well.

More torque means more power, at any given rpm.
Less torque means less power, at any given rpm.

For outright performance, high-rpm torque is what matters since your needle will simple stay in the upper rev range the whole time as you hunt redline in every gear, so low-end meaty torque is, in this respect, completely useless. Peak power is a much better performance indicator than peak torque.

Of course, the exception to the rule of hunting your redline for maximum acceleration would be if your torque goes down the toilet way before redline (which indicates a crappy tune that doesn't take advantage of gearing).

Bottom line: For the performance enthusiast it is always better to produce high torque at high rpm rather than high torque at low rpm.

My god thats the best explination I've ever heard! Are you in fact a genius?

 

[jc denton]

The point of this vote though was simply to find out what most people prefer; Low end torque or high end torque...

For me its POWEEERRR, Maximum revs, maximum noise, maxumum drama & no more money for petrol

 

[roauto]

Low end Torque. Smokey burnouts when 5-0 ain't lookin, Nice for autocross where the top speed is low. Speed limit makes low end torque King on the street!

 

[SLEEPER]

What MA means ( I think ) is that it isnt simply a choice of having one or the other - in fact if you leave out deisels the two go hand in hand

So the choice isnt one you need to make hence his and my complete lack of interest in the poll

But a few comments on the subject all the same

There is no such thing as low or high end torque - torque is torque

The lower the rev limit of the engine the more torque it will usually produce relative to the maximum power figures

And because BHP crosses torque at 5252 on a dyno graph the higher the rev limit the bigger difference in the two figures.

And tuning an engine will always increase both

 

[SLEEPER]

Of course, the exception to the rule of hunting your redline for maximum acceleration would be if your torque goes down the toilet way before redline (which indicates a crappy tune that doesn't take advantage of gearing).

Not so
The formulas for measuring torque and bhp dictate that the bhp curve crosses the torque curve at around 5252rpm .It has nothing to do with the engine design or how it is tuned .
many turbo engines for example produce rapidly increasing power (bhp) at high revs
even though the torque will have tailed off .

That is engine charachteristics not a crappy tune

And if you are doing things right you tune an engine then choose the gearing to suit its power and the cars weight etc. not the other way round

 

[stamford]

Sleeper I'm glad you posted as I looked yesterday and couldn't be bothered to explain it myself (too long winded) as the poll seemed pointless. Some do not understand the two and get confused. As you say there is a point when the two are of the same value. Going off slightly the bit that makes me laugh is when you get so called expert columnists mixing metric with imperial values.

 

[T9 man]

Some do not understand the two and get confused. As you say there is a point when the two are of the same value.

Er I am one of those people :embarrest: but I do understand the concept a little better now, so thank you for the explanation sleeper

 

[dannemare]

There is no such thing as low or high end torque - torque is torque

Of course, torque is torque!

When I say low-end torque I'm naturally referring to the engine's torque output in the lower end of the engine's rev range.

 

[dannemare]

Not so
The formulas for measuring torque and bhp dictate that the bhp curve crosses the torque curve at around 5252rpm .It has nothing to do with the engine design or how it is tuned .
many turbo engines for example produce rapidly increasing power (bhp) at high revs
even though the torque will have tailed off .

That is engine charachteristics not a crappy tune

And if you are doing things right you tune an engine then choose the gearing to suit its power and the cars weight etc. not the other way round

Of course, they will always cross at 5252 as per the math equation that they are both part of, but you're just not getting it. You are confusing yourself. Take power out of the picture for a minute and I'll explain to you how it all works and why I say you should always hunt your redline in every gear for maximum acceleration (unless your torque tails off rapidly way before redline in which case your transmission output torque in the current gear could happen to be so low that it will simply be feasible to upshift earlier than redline).

Okay, here goes....

My point simply is that for maximum acceleration, high-end torque is simply more important than low-end torque. Why, you ask? Because you can take advantage of gearing. You probably don't know this, but the transmission actually works as a torque multiplier and a lower gear is stronger than a higher. Nature of the beast.

Basically (and assuming you're running a properly tuned car with an optimal torque delivery curve) you should *always* downshift (hence, your revs increase; thus, torque high up the rev range is used) if there is room for a downshift. Why? Because of gearing and what is does to the torque delivered to the wheels. Wheel torque is what accelerates a car.

To learn more about the subject please read http://www.allpar.com/eek/hp-vs-torque.html by Ed Lansinger who is a design engineer at Ford Motor Company and former design engineer at GM Powertrain as well as inventor of Cadillac's Performance Algorithm Shifting feature.

 

[dannemare]

Transmission output torque delivery with a proper map (factory map for my old Opel Corsa OPC):

It should be clear to everybody where the optimal shift points are (namely at redline).

And here's a rather poorly remapped Grande Punto Abarth with a tune which unfortunately isn't designed properly to take advantage of gearing, plus you'll constantly have to consider what gear you're in to decide your optimal shift point. Poorly executed by the tuner....

 

[dannemare]

The above spreadsheet which I've created can be downloaded from http://sentinel.dk/tranny-output-torque-calculator.xls (or http://sentinel.dk/tranny-output-torque-calculator.ods if using OpenOffice).

All you have to do is type in the gear ratios of your car (I have left out the final drive, since it is a constant for all gears) as well as the torque numbers from a proper dyno run (for many graphs it can be a bit difficult to read the exact numbers at 500 rpm intervals, but give it a try...).

In other words, simply fill data into the cyan blue cells and all other numbers will then be calculated for you.

 

[dannemare]

My god thats the best explination I've ever heard!

Thanks.

Are you in fact a genius?

Nah...

 

[dannemare]

Transmission output torque delivery with a proper map (factory map for my old Opel Corsa OPC):

It should be clear to everybody where the optimal shift points are (namely at redline).

A few comments and how to interpret my data:

Let's start out by looking at 1st, 2nd, 3rd gear. From this it's pretty clear that tranny output torque at redline is always higher in a lower gear than the next one (at any given RPM). Hence, run it to redline for maximum acceleration.

Moving on to 4th gear we now see that tranny output torque is actually lower at 6500 RPM than in the next (5th) gear at 2500 RPM. Does this mean we should upshift to 5th sooner than redline? No, because shifting at, say, 6000 RPM instead (which has higher torque than any RPM in the next gear) will drop us back to circa 5000 RPM and only a maximum of 151 foot-pound of torque (dropping all the way to 128 at redline) whereas going for redline in 4th yields 155 strong ones. The scenario for 5th -> 6th is similar.

I hope I have explained it well enough...

 

[Zwaf]

Thank you, Dannemare!
Very informative and explains a lot!

 

[SLEEPER]

Dannenare
It is best to read a post before you quote and reply to it

Thanks for the in depth torque explanation which I neither needed or wanted .
If you actually read my post I DIDNT ACTUALLY DISAGREE WITH YOU apart from

1 the bits about gearing a car to its characteristics not the other way round AND
2 the bit about if torque tailis off before the redline it means a crap map
I womt bother with the first cos that is so obvious

Re 2 This is not a crap map just because the torque tails off noticably before the redline (which is set at 8350 though the car will rev to over 9000)

 

[dannemare]

Thanks for the in depth torque explanation which I neither needed or wanted .

But you're still glad I explained it all in great detail, aren't you.

2 the bit about if torque tailis off before the redline it means a crap map

Okay, so "crap" was a strong word. Let's just say "suboptimal" (in the eyes of the performance enthusiast).

It is the degree to which a torque curve drops off that matters. You need to go back and reread by posts where I talk about optimal shift points and what dictates an optimal shift point (namely transmission output torque!!). Nothing wrong with torque dropping towards the end of the rev range (it's a perfectly natural engine characteristic), but if it falls flat on its face and thereby makes it suboptimal to take it all the way to redline in each individual gears, the tuner needs to learn about gearing and how to take advantage of gearing to develop the best mapping possible.

 

[SLEEPER]

you need to understand that this is a discussion forum not a lesson. People read and reply to what you say not what you meant

Also paragraphs of technwaffle wont impress anyone that understands the topic already.

why not post some pics and spec of your car instead

 

[dannemare]

you need to understand that this is a discussion forum not a lesson. People read and reply to what you say not what you meant

Also paragraphs of technwaffle wont impress anyone that understands the topic already.

Fair enough.

why not post some pics and spec of your car instead

Pictures, youtube videos and specs of my car is here: http://www.torquecars.com/forums/f90/focus-owners-say-hello-2280/index2.html#post185940

 

[dannemare]

And here's a dyno sheet from half a year ago...

(yellow is torque; red is power)

 

[kain35m]

I like horsepotatoes and torquematoes.

 

[Prince]

The point of this vote though was simply to find out what most people prefer; Low end torque or high end torque...

For me its POWEEERRR, Maximum revs, maximum noise, maxumum drama & no more money for petrol

You would say that, you own a Honda .

After having a Honda and a BMW I definitely prefer the car with torque (which also has a higher top end, just less rev happy). So I have voted torque for the sake of the poll.

However, this thread could have been close after MA posted as he was right. You don't have to choose.

 

[HDi fun]

Torque and power go hand in hand. It's a question of where in the usable rev range you want the torque and therefore the power to be.