On 08/04/2016 11:50, Dave Plowman (News) wrote:


How many many times do I have to say I'm only commenting on the best
acceleration *in any one gear* - so entirely due to engine output.

And, to a man, everyone agrees with you on that narrow point.

But that doesn't mean that any discussion about to get the best
acceleration when you're not constrained to use just one gear is invalid.


And I'm utterly amazed so few understand the relationship between torque
and power.


That's the problem - we *do*! We know that power = torque x speed (or
torque = power/speed) - with the result that, in order to get the
maximum possible output torque from a gearbox at any given speed (which
is what accelerates a car) you need to put the maximum possible power in.

Since there are very cars in existence with only one gear, it is
perfectly legitimate to take the gearbox into account when discussing
acceleration - even though you regard it as a "red herring".
--
Cheers,
Roger
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In message , "Dave Plowman (News)"
writes
In article ,
michael adams wrote:

Given that torque is the power transmitted via the drive axle which
causes the wheels to rotate, its difficult to see what's wrong with his
claim, quite honestly.

Hasn't stopped many trying. And failing.

Except maybe in cars fitted with sails.

Would that be 'thrust'? ;-)

To try and introduce an element of humour.... I was intrigued reading an
Autosport? magazine report on 0-60mph trials for a series 2 Morgan
around 1960 to learn that *all upward gear changes were carried out at
full throttle*:-)


--
Tim Lamb

On 07/04/16 22:24, wrote:
It seems that you're saying that becase Power is obtained at the TOP
of the power curve and Peak Torque much lower on the power curve,
that a car will accelerate more rapidly between 90 and 100 mph than
it will between 40 and 50 MPH.


It seems you are Dave Plowman, and I claim my £5

Engine RPM is not directly and irrevocably poroprtional to road speed

WE have a gearbox.


--
New Socialism consists essentially in being seen to have your heart in
the right place whilst your head is in the clouds and your hand is in
someone else's pocket.

"Dave Plowman (News)" wrote in message
...
In article ,
michael adams wrote:
If the engine is running at maximum power, and thus the crankshaft
is turning as fast as possible, then how is it possible for less than
maximum torque to be delivered to the flywheel ?

I'm beginning to lose the will to live.

Power is a function of torque and engine speed. It therefore goes without
saying that maximum power will always be delivered at higher revs than
maximum torque in practice.

That may well go without saying for you, but it isn't intuitively
obvious to me.

It may have said something similar on some website, complete with
diagrams and coloured lines, so I'm not going to tear my hair
out over it, either way.


michael adams

....

In article ,
Roger Mills wrote:
How many many times do I have to say I'm only commenting on the best
acceleration *in any one gear* - so entirely due to engine output.

And, to a man, everyone agrees with you on that narrow point.

If only. Lots and lots say it's at maximum power, not maximum torque.

That's what started this entire 'discussion'.

--
*A picture may be worth a thousand words, but it uses up a thousand times more memory.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
The Natural Philosopher wrote:
On 07/04/16 22:24, wrote:
It seems that you're saying that becase Power is obtained at the TOP
of the power curve and Peak Torque much lower on the power curve,
that a car will accelerate more rapidly between 90 and 100 mph than
it will between 40 and 50 MPH.


It seems you are Dave Plowman, and I claim my £5

Easy to tell the difference as I only talk sense.

Engine RPM is not directly and irrevocably poroprtional to road speed

WE have a gearbox.

And you win the cigar for stating the bleeding obvious.

Now go and find out about torque and BHP. Even an idiot can use Google.
Get one to show you how.

-

--
*We waste time, so you don't have to *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
michael adams wrote:

"Dave Plowman (News)" wrote in message
...
In article ,
michael adams wrote:
If the engine is running at maximum power, and thus the crankshaft
is turning as fast as possible, then how is it possible for less than
maximum torque to be delivered to the flywheel ?

I'm beginning to lose the will to live.

Power is a function of torque and engine speed. It therefore goes
without saying that maximum power will always be delivered at higher
revs than maximum torque in practice.

That may well go without saying for you, but it isn't intuitively
obvious to me.

It is simple maths. If BHP is a function of RPM and torque, and the torque
remains constant, then higher RPM means higher BHP.

It may have said something similar on some website, complete with
diagrams and coloured lines, so I'm not going to tear my hair
out over it, either way.

If you looked at graphs showing an engine's output relative to RPM, you'd
see two plots, one for BHP and the other for torque. Often shown in the
same graph. Both will rise and then fall as RPM increases. The torque one
will have its peak at lower RPM than the BHP.

It's something I've known since a child. ;-)

--
*The severity of the itch is proportional to the reach *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
michael adams wrote:

"Dave Plowman (News)" wrote in message
...
In article ,
michael adams wrote:
If the engine is running at maximum power, and thus the crankshaft
is turning as fast as possible, then how is it possible for less than
maximum torque to be delivered to the flywheel ?

I'm beginning to lose the will to live.

Power is a function of torque and engine speed. It therefore goes
without saying that maximum power will always be delivered at higher
revs than maximum torque in practice.

That may well go without saying for you, but it isn't intuitively
obvious to me.

It is simple maths. If BHP is a function of RPM and torque, and the torque
remains constant, then higher RPM means higher BHP.

But why should the torque remain constant ?

It may have said something similar on some website, complete with
diagrams and coloured lines, so I'm not going to tear my hair
out over it, either way.

If you looked at graphs showing an engine's output relative to RPM, you'd
see two plots, one for BHP and the other for torque. Often shown in the
same graph. Both will rise and then fall as RPM increases. The torque one
will have its peak at lower RPM than the BHP.

It's something I've known since a child. ;-)

But doesn't that contradict what you were saying earlier about
torque ? Now you seem to be saying peak power is reached at peak
RPM and not peak torque.


michael adams

....

In article ,
michael adams wrote:

"Dave Plowman (News)" wrote in message
...
In article ,
michael adams wrote:

"Dave Plowman (News)" wrote in message
...
In article ,
michael adams wrote:
If the engine is running at maximum power, and thus the crankshaft
is turning as fast as possible, then how is it possible for less than
maximum torque to be delivered to the flywheel ?

I'm beginning to lose the will to live.

Power is a function of torque and engine speed. It therefore goes
without saying that maximum power will always be delivered at higher
revs than maximum torque in practice.

That may well go without saying for you, but it isn't intuitively
obvious to me.

It is simple maths. If BHP is a function of RPM and torque, and the
torque remains constant, then higher RPM means higher BHP.

But why should the torque remain constant ?

On an ideal engine, it would, at maximum demand. Like it (almost) does on
some types of electric motor.

It may have said something similar on some website, complete with
diagrams and coloured lines, so I'm not going to tear my hair
out over it, either way.

If you looked at graphs showing an engine's output relative to RPM,
you'd see two plots, one for BHP and the other for torque. Often shown
in the same graph. Both will rise and then fall as RPM increases. The
torque one will have its peak at lower RPM than the BHP.

It's something I've known since a child. ;-)

But doesn't that contradict what you were saying earlier about torque ?
Now you seem to be saying peak power is reached at peak RPM and not peak
torque.

Think you need to read what I wrote again. Carefully.

Peak RPM is generally higher than where peak BHP occurs. Again, obviously.

Please don't use 'power' as it seems to confuse so many on here. The term
is BHP - brake horse power.

--
*Keep honking...I'm reloading.

Dave Plowman London SW
To e-mail, change noise into sound.

On Fri, 08 Apr 2016 12:46:27 +0100, Tim Lamb wrote:

In message , "Dave Plowman (News)"
writes
In article ,
michael adams wrote:

Given that torque is the power transmitted via the drive axle which
causes the wheels to rotate, its difficult to see what's wrong with
his claim, quite honestly.

Hasn't stopped many trying. And failing.

Except maybe in cars fitted with sails.

Would that be 'thrust'? ;-)

To try and introduce an element of humour.... I was intrigued reading an
Autosport? magazine report on 0-60mph trials for a series 2 Morgan
around 1960 to learn that *all upward gear changes were carried out at
full throttle*:-)


That's a technique I used to use myself over two decades ago when
driving the works van over short motorway sections on job to job journeys.

Assuming the clutch can tolerate such abuse[1], it's a valid way to
wring every last drop of acceleration performance out an engine power
train.

[1] Frequent empirical testing suggested this happened to be so in my
case. :-)

--
Johnny B Good

On 08/04/2016 15:49, Dave Plowman (News) wrote:


Please don't use 'power' as it seems to confuse so many on here. The term
is BHP - brake horse power.


No - the correct term *is* power when talking about that commodity. BHP
is just one of the units in which it is measured - along with kW and PS.

Just as "speed" is a valid term - or velocity if you also want to
specify the direction of travel - regardless of whether you are
measuring it in MPH, KPH, FPS, etc.
--
Cheers,
Roger
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On 08/04/2016 12:46, Tim Lamb wrote:


To try and introduce an element of humour.... I was intrigued reading an
Autosport? magazine report on 0-60mph trials for a series 2 Morgan
around 1960 to learn that *all upward gear changes were carried out at
full throttle*:-)



That's fine if you have sufficient skill - and are driving someone
else's car! You don't have to hang around making the gearchanges, though.
--
Cheers,
Roger
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"Roger Mills" wrote in message
...
On 08/04/2016 15:49, Dave Plowman (News) wrote:


Please don't use 'power' as it seems to confuse so many on here. The term
is BHP - brake horse power.


No - the correct term *is* power when talking about that commodity. BHP is just one of
the units in which it is measured - along with kW and PS.

I'm getting all confused now. Much more of this and I'll need
counselling.



michael adams

....

On 08/04/2016 12:03, Dave Plowman (News) wrote:
Have said this countless times. But didn't stop others saying this was
wrong - or introducing countless red herrings and moving of goal posts.

It's what started the original thread and caused Vir to start this one.

But it seems he's not alone in having little understanding of basic
mechanics.

I am reading this, and I'll try one last time.

Torque is irrelevant to performance. I know it's hard for you to
understand, and it doesn't agree with your prejudices, but it's true.

For a car with a gearbox - and that is all of them - to get highest
performance you ignore peak torque, and keep the engine at maximum
power, or as close as you can get.

You can easily see this if you just work out the torque at the gearbox
output for these two cases
400nM at 2000RPM
200nM at 5000RPM
with ratios chosen to give the same speed at the output shaft - the
higher revs, lower torque will give you 25% more torque at any given
output speed of the gearbox.

It's true that if you can't change gear you'll get the highest
acceleration at peak torque. But that is not relevant to getting the
highest performance.

If you compare cars with similar peak torque outputs, but different
power outputs the performance won't match. But if you look at cars with
similar power outputs, but different torque outputs the figures will match.

Look here - BMW's 5 series
http://www.bmw.co.uk/en_GB/new-vehicles/5/saloon/2013/technicaldata.html

Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Andy

On Friday, 8 April 2016 13:03:23 UTC+1, The Natural Philosopher wrote:
On 07/04/16 22:24, wrote:
It seems that you're saying that becase Power is obtained at the TOP
of the power curve and Peak Torque much lower on the power curve,
that a car will accelerate more rapidly between 90 and 100 mph than
it will between 40 and 50 MPH.


It seems you are Dave Plowman, and I claim my £5

Engine RPM is not directly and irrevocably poroprtional to road speed

WE have a gearbox.


Yes, and in every gear the engine RPM is directly and irrevocably proportional
to road speed.

The speed/time graphs are exactly the same shape in every gear. Acceleration is greatest at the
highest TORQUE regardless of which gear is selected.

Torque is irrelevant to performance.

The most ridiculous statement of the thread (so far).


Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Well, the two 520s are Diesels, and don't have the RPM range that the Petrol 528 has; they are governed to 4000 RPM.

On 08/04/2016 21:41, Vir Campestris wrote:
On 08/04/2016 12:03, Dave Plowman (News) wrote:
Have said this countless times. But didn't stop others saying this was
wrong - or introducing countless red herrings and moving of goal posts.

It's what started the original thread and caused Vir to start this one.

But it seems he's not alone in having little understanding of basic
mechanics.

I am reading this, and I'll try one last time.

Torque is irrelevant to performance. I know it's hard for you to
understand, and it doesn't agree with your prejudices, but it's true.

For a car with a gearbox - and that is all of them - to get highest
performance you ignore peak torque, and keep the engine at maximum
power, or as close as you can get.

You can easily see this if you just work out the torque at the gearbox
output for these two cases
400nM at 2000RPM
200nM at 5000RPM
with ratios chosen to give the same speed at the output shaft - the
higher revs, lower torque will give you 25% more torque at any given
output speed of the gearbox.

It's true that if you can't change gear you'll get the highest
acceleration at peak torque. But that is not relevant to getting the
highest performance.

If you compare cars with similar peak torque outputs, but different
power outputs the performance won't match. But if you look at cars with
similar power outputs, but different torque outputs the figures will match.

Look here - BMW's 5 series
http://www.bmw.co.uk/en_GB/new-vehicles/5/saloon/2013/technicaldata.html

Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Andy


Nice one!
--
Cheers,
Roger
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On 08/04/2016 22:13, wrote:

Torque is irrelevant to performance.

The most ridiculous statement of the thread (so far).

While I agree it is not entirely irrelevant to performance it is a
consequence of engine power and it's ability to supply the energy to the
car ending up in kinetic energy.

It would be similar to claiming that the speed of sound is dependent on
temperature.

Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Well, the two 520s are Diesels, and don't have the RPM range that the Petrol 528 has; they are governed to 4000 RPM.

While peak power is an indicator of engine power, the acceleration
calculation would be of the form:

For the 528i, energy of car at 62mph (0.5 x m v^2) = integral(0 to
6.2s) of Engine Power(t) dt

where engine power is that supplied at any instant of the acceleration test.

I might agree that maximum acceleration in any gear would occur at the
maximum engine torque in that gear, the fact in itself is most unhelpful
in determining 0 to 60mph times.

On 08/04/2016 22:13, wrote:

Torque is irrelevant to performance.

The most ridiculous statement of the thread (so far).


Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Well, the two 520s are Diesels, and don't have the RPM range that the Petrol 528 has; they are governed to 4000 RPM.


I don't somehow think that the 520i is a Diesel *or* that produces 135
HP without going above 4000 RPM. Try again!
--
Cheers,
Roger
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checked.

On 08/04/16 21:43, wrote:
On Friday, 8 April 2016 13:03:23 UTC+1, The Natural Philosopher wrote:
On 07/04/16 22:24, wrote:
It seems that you're saying that becase Power is obtained at the TOP
of the power curve and Peak Torque much lower on the power curve,
that a car will accelerate more rapidly between 90 and 100 mph than
it will between 40 and 50 MPH.


It seems you are Dave Plowman, and I claim my £5

Engine RPM is not directly and irrevocably poroprtional to road speed

WE have a gearbox.


Yes, and in every gear the engine RPM is directly and irrevocably proportional
to road speed.

The speed/time graphs are exactly the same shape in every gear. Acceleration is greatest at the
highest TORQUE regardless of which gear is selected.

well no, *only in that gear*. In a lower gear at peak power,
acceleration will be greater.

You are Dave Plowman and I claim my £5



--
Ideas are more powerful than guns. We would not let our enemies have
guns, why should we let them have ideas?

Josef Stalin

On 08/04/16 22:13, wrote:

Torque is irrelevant to performance.

The most ridiculous statement of the thread (so far).


Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Well, the two 520s are Diesels, and don't have the RPM range that the Petrol 528 has; they are governed to 4000 RPM.

ITYM 4500. I have that diesel in my freelander


--
Ideas are more powerful than guns. We would not let our enemies have
guns, why should we let them have ideas?

Josef Stalin

On 08/04/2016 21:43, wrote:
On Friday, 8 April 2016 13:03:23 UTC+1, The Natural Philosopher wrote:


Engine RPM is not directly and irrevocably poroprtional to road speed

WE have a gearbox.


Yes, and in every gear the engine RPM is directly and irrevocably proportional
to road speed.


That's only true for a manual transmission. At the risk of being accused
by you know who of introducing another red herring, as soon as you
insert a torque converter between the engine and gearbox, your cosy
relationship goes out the window! So we ignore that, and assume that we
have a conventional manual transmission.


The speed/time graphs are exactly the same shape in every gear.

They're not, actually. They get considerably less steep in each
successive gear.

Gearbox output torque vs road speed graphs are essentially the same
shape in each gear but are, of course, scaled differently.

Acceleration is greatest at the
highest TORQUE regardless of which gear is selected.

This is where we go round in circles! It's true that peak acceleration
in each *gear* coincides with the engine's peak torque. But, in many
cases, you can obtain a *higher* acceleration at a given road speed by
using a different gear and running the engine at max power.

That acceleration will be lower than you would get in that 'different'
gear at peak engine torque but it would be at a higher road speed. For
maximum accelerative performance you need the maximum available
acceleration all the way up the speed range - so you need to run the
engine as close to max power as possible.
--
Cheers,
Roger
____________
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checked.

In article ,
Tim Lamb wrote:
To try and introduce an element of humour.... I was intrigued reading an
Autosport? magazine report on 0-60mph trials for a series 2 Morgan
around 1960 to learn that *all upward gear changes were carried out at
full throttle*:-)

Didn't some Morgans

--
*A closed mouth gathers no feet.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
wrote:

Torque is irrelevant to performance.

The most ridiculous statement of the thread (so far).

And Vir is the one who started this nonsense months ago. But won't be told.


Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Well, the two 520s are Diesels, and don't have the RPM range that the
Petrol 528 has; they are governed to 4000 RPM.

What any car's 0-60 time may be is totally irrelevant to where the maximum
acceleration occurs anyway. Unless comparing apples to oranges.

--
*What do little birdies see when they get knocked unconscious? *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Roger Mills wrote:
Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Andy


Nice one!

Except that if you checked the best 10 mph increment in speed between the
three, the diesel probably wins...

--
*Cover me. I'm changing lanes.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Fredxxx wrote:
I might agree that maximum acceleration in any gear would occur at the
maximum engine torque in that gear, the fact in itself is most unhelpful
in determining 0 to 60mph times.

And in the original discussion, 0-60 times weren't mentioned. Just the
point in an engine's output where the best acceleration occurred. Which of
course is at maximum torque, not maximum BHP.

Actual 0-60 times depends on so much more.

--
*After the game, the King and the pawn go into the same box.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
The Natural Philosopher wrote:
On 08/04/16 22:13, wrote:

Torque is irrelevant to performance.

The most ridiculous statement of the thread (so far).


Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Well, the two 520s are Diesels, and don't have the RPM range that the Petrol 528 has; they are governed to 4000 RPM.

ITYM 4500. I have that diesel in my freelander

Ah. A Freelander. Explains why you don't understand performance.

--
*Verbs HAS to agree with their subjects *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Roger Mills wrote:
This is where we go round in circles! It's true that peak acceleration
in each *gear* coincides with the engine's peak torque.

Thank gawd for that.

But, in many
cases, you can obtain a *higher* acceleration at a given road speed by
using a different gear and running the engine at max power.

And has anyone ever denied that? Although I think you mean a lower gear.

Now all you need to do is persuade Mr Camp.

--
*By the time a man is wise enough to watch his step, he's too old to go anywhere.

Dave Plowman London SW
To e-mail, change noise into sound.

On 09/04/2016 00:11, Dave Plowman (News) wrote:
In ,
Roger wrote:
This is where we go round in circles! It's true that peak acceleration
in each *gear* coincides with the engine's peak torque.

Thank gawd for that.

But, in many
cases, you can obtain a *higher* acceleration at a given road speed by
using a different gear and running the engine at max power.

And has anyone ever denied that?

Apart from you, do you mean?

Although I think you mean a lower gear.

Yes, of course. My "different" gear would obviously need to be lower to
get the effect I described.


Now all you need to do is persuade Mr Camp.


I don't think he needs persuading.
--
Cheers,
Roger
____________
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checked.

On 08/04/2016 23:57, Dave Plowman (News) wrote:
In ,
wrote:

Torque is irrelevant to performance.

The most ridiculous statement of the thread (so far).

And Vir is the one who started this nonsense months ago. But won't be told.


Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Well, the two 520s are Diesels, and don't have the RPM range that the
Petrol 528 has; they are governed to 4000 RPM.

What any car's 0-60 time may be is totally irrelevant to where the maximum
acceleration occurs anyway. Unless comparing apples to oranges.


The fact remains that a car's power to weight ratio (*not* engine torque
to weight ratio) is a pretty good indicator of accelerative performance.
--
Cheers,
Roger
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On 09/04/2016 00:02, Dave Plowman (News) wrote:
In ,
Roger wrote:
Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Andy


Nice one!

Except that if you checked the best 10 mph increment in speed between the
three, the diesel probably wins...


Now who's comparing apples with pears?
--
Cheers,
Roger
____________
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checked.

In article ,
Roger Mills wrote:
On 09/04/2016 00:11, Dave Plowman (News) wrote:
In ,
Roger wrote:
This is where we go round in circles! It's true that peak acceleration
in each *gear* coincides with the engine's peak torque.

Thank gawd for that.

But, in many
cases, you can obtain a *higher* acceleration at a given road speed by
using a different gear and running the engine at max power.

And has anyone ever denied that?

Apart from you, do you mean?

Please quote where I have. You'll find that impossible.

Although I think you mean a lower gear.

Yes, of course. My "different" gear would obviously need to be lower to
get the effect I described.


Now all you need to do is persuade Mr Camp.


I don't think he needs persuading.

No. He thinks the best acceleration takes place at maximum BHP. The whole
reason this started. And he is wrong then as now.

--
*If I agreed with you, we'd both be wrong.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Roger Mills wrote:
What any car's 0-60 time may be is totally irrelevant to where the
maximum acceleration occurs anyway. Unless comparing apples to oranges.


The fact remains that a car's power to weight ratio (*not* engine torque
to weight ratio) is a pretty good indicator of accelerative performance.

It's an oft quoted figure for the masses. Same as BHP is all important to
bar room mechanics. But it doesn't tell the full story. Only that car
makers tend to produce roughly similar engines.

But I'll ask you a question. Take a high revving bike engine with a very
high specific BHP per litre and put it up against a lightly stressed but
torquey V8 etc in vehicles with the same power to weight ratio. Which one
will accelerate better?

--
*Any connection between your reality and mine is purely coincidental

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Roger Mills wrote:
On 09/04/2016 00:02, Dave Plowman (News) wrote:
In ,
Roger wrote:
Model 0-62 peak power peak torque
520D 7.9 140 400
520i 7.9 135 270
528i 6.2 180 350

Now explain how the 528i with _less_ torque than the 520D is so much
faster. And the two 520s match.

Andy


Nice one!

Except that if you checked the best 10 mph increment in speed between
the three, the diesel probably wins...


Now who's comparing apples with pears?

I was never ever discussing 0-60 times in this particular discussion. It's
merely a pub bore benchmark.

I would remind you of what this discussion was about, but if you don't
know by now, no point.

--
*WHAT IF THERE WERE NO HYPOTHETICAL QUESTIONS?

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...

Same as BHP is all important to bar room mechanics.


"Dave Plowman (News)" wrote in message
...

Please don't use 'power' as it seems to confuse so many on here. The term
is BHP - brake horse power.



michael adams

....

On 09/04/2016 11:33, Dave Plowman (News) wrote:
In ,
Roger wrote:
On 09/04/2016 00:11, Dave Plowman (News) wrote:
In ,
Roger wrote:
This is where we go round in circles! It's true that peak acceleration
in each *gear* coincides with the engine's peak torque.

Thank gawd for that.

But, in many
cases, you can obtain a *higher* acceleration at a given road speed by
using a different gear and running the engine at max power.

And has anyone ever denied that?

Apart from you, do you mean?

Please quote where I have. You'll find that impossible.


I don't need to try very hard, do I? Just look at your very last
statement (below) in *this* post!

I thought from what you wrote above that the truth had finally dawned on
you. But I was wrong!


Although I think you mean a lower gear.

Yes, of course. My "different" gear would obviously need to be lower to
get the effect I described.


Now all you need to do is persuade Mr Camp.


I don't think he needs persuading.

No. He thinks the best acceleration takes place at maximum BHP. The whole
reason this started. And he is wrong then as now.



--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On 09/04/2016 00:05, Dave Plowman (News) wrote:
In article ,
Fredxxx wrote:
I might agree that maximum acceleration in any gear would occur at the
maximum engine torque in that gear, the fact in itself is most unhelpful
in determining 0 to 60mph times.

And in the original discussion, 0-60 times weren't mentioned. Just the
point in an engine's output where the best acceleration occurred. Which of
course is at maximum torque, not maximum BHP.

Actual 0-60 times depends on so much more.

If you can understand the OP's question, you will accept that there are
scant details to provide an answer.

I was commenting on the assertion that torque is an irrelevance to the
acceleration of a car where 0-62mph times were mentioned. The OP's
question was something like 40 posts ago in this specific thread.

On 09/04/2016 12:14, michael adams wrote:
"Dave Plowman (News)" wrote in message
...

Same as BHP is all important to bar room mechanics.


"Dave Plowman (News)" wrote in message
...

Please don't use 'power' as it seems to confuse so many on here. The term
is BHP - brake horse power.

If you want the least confusing measurement of power then use Watts, or
even KW. They are also an SI unit.

If people here don't know how to calculate power from torque and revs,
then they ought to excuse themselves from this discussion and learn.

In article ,
michael adams wrote:

"Dave Plowman (News)" wrote in message
...

Same as BHP is all important to bar room mechanics.


"Dave Plowman (News)" wrote in message
...

Please don't use 'power' as it seems to confuse so many on here. The
term is BHP - brake horse power.



And? Just what you find in that worth pasting without comment?

--
*Succeed, in spite of management *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Roger Mills wrote:
On 09/04/2016 11:33, Dave Plowman (News) wrote:
In ,
Roger wrote:
On 09/04/2016 00:11, Dave Plowman (News) wrote:
In ,
Roger wrote:
This is where we go round in circles! It's true that peak acceleration
in each *gear* coincides with the engine's peak torque.

Thank gawd for that.

But, in many
cases, you can obtain a *higher* acceleration at a given road speed by
using a different gear and running the engine at max power.

And has anyone ever denied that?

Apart from you, do you mean?

Please quote where I have. You'll find that impossible.


I don't need to try very hard, do I? Just look at your very last
statement (below) in *this* post!

I thought from what you wrote above that the truth had finally dawned on
you. But I was wrong!

Then please quote me saying you *won't* get better acceleration in a lower
gear?

Either you're trolling or you haven't grasped what this thread is about.


Although I think you mean a lower gear.

Yes, of course. My "different" gear would obviously need to be lower to
get the effect I described.


Now all you need to do is persuade Mr Camp.


I don't think he needs persuading.

No. He thinks the best acceleration takes place at maximum BHP. The whole
reason this started. And he is wrong then as now.


--
*A plateau is a high form of flattery*

Dave Plowman London SW
To e-mail, change noise into sound.