On 03/04/2016 10:41, Roger Mills wrote:
On 02/04/2016 22:57, The Natural Philosopher wrote:
On 02/04/16 22:53, Roger Mills wrote:
On 02/04/2016 18:11, The Natural Philosopher wrote:
On 02/04/16 18:01, Roger Mills wrote:
On 02/04/2016 14:15, Dave Plowman (News) wrote:


As I said before, some seem totally incapable of understanding a very
simple and basic condition.


I think we agree on THAT! What we DON'T agree on is who those people
ARE!!!!

You and Dave, basically.



Pray what simple and basic condition have *I* failed to understand?

Gearboxes. The relationship between power torque acceleration and speed.
Basic mechanical engineering.
Take your pick.


Rubbish! I challenge to you quote anything I wrote which backs up your
statement.

Your silence is deafening, Mr "Philosopher". I'm still waiting for your
abject apology!
--
Cheers,
Roger
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On 04/04/16 14:13, Roger Mills wrote:
On 03/04/2016 10:41, Roger Mills wrote:
On 02/04/2016 22:57, The Natural Philosopher wrote:
On 02/04/16 22:53, Roger Mills wrote:
On 02/04/2016 18:11, The Natural Philosopher wrote:
On 02/04/16 18:01, Roger Mills wrote:
On 02/04/2016 14:15, Dave Plowman (News) wrote:


As I said before, some seem totally incapable of understanding a
very
simple and basic condition.


I think we agree on THAT! What we DON'T agree on is who those people
ARE!!!!

You and Dave, basically.



Pray what simple and basic condition have *I* failed to understand?

Gearboxes. The relationship between power torque acceleration and speed.
Basic mechanical engineering.
Take your pick.


Rubbish! I challenge to you quote anything I wrote which backs up your
statement.

Your silence is deafening, Mr "Philosopher". I'm still waiting for your
abject apology!

Sorry. I didn't see the previous post.

The mere fact that you agree with D plowman is sufficient evidence. I
rest my case.


--
No Apple devices were knowingly used in the preparation of this post.

On 04/04/2016 11:16, Dave Plowman (News) wrote:
In ,
Roger wrote:
On 03/04/2016 21:44, Vir Campestris wrote:
On 02/04/2016 18:01, Roger Mills wrote:
Of course there would. It would only be at its max value at the max
torque point itself - which may actually cover a range of speeds since
some engine torque curves are flatish rather than peaky at max torque.
We're talking about a dynamic rather than static situation anyway.
Acceleration is the RATE OF CHANGE of speed and is a continuously
variable function. If you're defining acceleration as a step change in
speed it's little wonder that you're living on a different cloud from
everyone else.

Maybe I need to change A1 for your benefit, thus:

A1: By using full throttle and allowing the car to accelerate over a
speed range which encompasses the max torque speed of the engine.
Maximum acceleration will occur as the engine passes through its max
torque point.

[In actual fact, it may not! As the car speed increases, the aerodynamic
drag increases as the square of the speed. The effect of this - which we
have so far ignored in this discussion - is that maximum acceleration
MAY occur slightly below the max torque speed because the increase in
drag may more than offset the increase in torque.]

I've given up on Plowman, he must be trolling. Or too embarrassed to
admit he's wrong.

Your A1 as it is written is perfectly true, but irrelevant for performance.

Yes, I'm aware of that - and was simply trying to explain to Mr Plowman
that his assertion only applies if you restrict yourself to one gear.


If talking about the maximum accleration point in an engine's output over
its speed range, why would you not restrict it to one gear? Surely you
realise that what applies in one gear will also apply to another?

To get the greatest acceleration for a car you need to maximise the
amount of power that the engine generates.


Yes, indeed.

No it's ********. You need to maximise the torque. Not power.

You need to maximise the torque at the *wheels*. Don't forget, there's a
gearbox between the engine and the wheels. As you keep reminding us, a
gearbox magnifies the torque. But that comes at the expense of speed. So
- as should be obvious - you need a higher engine speed to maintain a
given road speed in a low gear than you would in a higher gear. And when
the engine is at its max power point you get the highest available
product of output speed and torque - which is what you want.


That's what I've been saying all along. That's why I gave
the example of using a continuously variable transmission to hold the
engine at its max power (*NOT* max torque) speed as the car accelerates.

Care to explain why a CVT holds the engine at maximum torque, then?


I'm not aware that it does. If I were to design one, it certainly wouldn't!

It's obvious when you consider that power = thrust x speed. At any given
speed, the higher the power the higher the thrust.

I've no idea what you mean by 'thrust' That's something usually associated
with a jet engine. Power is a function of torque and RPM. And the higher
the power does *not* mean the higher the torque.


Newton's first law! A body remains at rest or moves at a constant speed
in a straight line unless acted upon by "forces".

In order to accelerate a car, you need an external force. That force is
imparted to the car through the contact patch. The torque imparted on
the wheels through the transmission manifests itself as a force at the
contact patch which tries to push the road backwards. But the road
usually wins, and pushes the car forwards instead. *That* is the thrust
to which I was referring.
--
Cheers,
Roger
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checked.

On 04/04/16 14:29, Roger Mills wrote:
On 04/04/2016 11:16, Dave Plowman (News) wrote:
In ,
Roger wrote:
On 03/04/2016 21:44, Vir Campestris wrote:
On 02/04/2016 18:01, Roger Mills wrote:
Of course there would. It would only be at its max value at the max
torque point itself - which may actually cover a range of speeds since
some engine torque curves are flatish rather than peaky at max torque.
We're talking about a dynamic rather than static situation anyway.
Acceleration is the RATE OF CHANGE of speed and is a continuously
variable function. If you're defining acceleration as a step change in
speed it's little wonder that you're living on a different cloud from
everyone else.

Maybe I need to change A1 for your benefit, thus:

A1: By using full throttle and allowing the car to accelerate over a
speed range which encompasses the max torque speed of the engine.
Maximum acceleration will occur as the engine passes through its max
torque point.

[In actual fact, it may not! As the car speed increases, the
aerodynamic
drag increases as the square of the speed. The effect of this -
which we
have so far ignored in this discussion - is that maximum acceleration
MAY occur slightly below the max torque speed because the increase in
drag may more than offset the increase in torque.]

I've given up on Plowman, he must be trolling. Or too embarrassed to
admit he's wrong.

Your A1 as it is written is perfectly true, but irrelevant for
performance.

Yes, I'm aware of that - and was simply trying to explain to Mr Plowman
that his assertion only applies if you restrict yourself to one gear.


If talking about the maximum accleration point in an engine's output over
its speed range, why would you not restrict it to one gear? Surely you
realise that what applies in one gear will also apply to another?

To get the greatest acceleration for a car you need to maximise the
amount of power that the engine generates.


Yes, indeed.

No it's ********. You need to maximise the torque. Not power.

You need to maximise the torque at the *wheels*. Don't forget, there's a
gearbox between the engine and the wheels. As you keep reminding us, a
gearbox magnifies the torque. But that comes at the expense of speed. So
- as should be obvious - you need a higher engine speed to maintain a
given road speed in a low gear than you would in a higher gear. And when
the engine is at its max power point you get the highest available
product of output speed and torque - which is what you want.


That's what I've been saying all along. That's why I gave
the example of using a continuously variable transmission to hold the
engine at its max power (*NOT* max torque) speed as the car accelerates.

Care to explain why a CVT holds the engine at maximum torque, then?


I'm not aware that it does. If I were to design one, it certainly wouldn't!

It's obvious when you consider that power = thrust x speed. At any given
speed, the higher the power the higher the thrust.

I've no idea what you mean by 'thrust' That's something usually
associated
with a jet engine. Power is a function of torque and RPM. And the higher
the power does *not* mean the higher the torque.


Newton's first law! A body remains at rest or moves at a constant speed
in a straight line unless acted upon by "forces".

In order to accelerate a car, you need an external force. That force is
imparted to the car through the contact patch. The torque imparted on
the wheels through the transmission manifests itself as a force at the
contact patch which tries to push the road backwards. But the road
usually wins, and pushes the car forwards instead. *That* is the thrust
to which I was referring.

And the point you and plowperson refuse to accept is that you will get
more thrust at the contact patch by running the engine at peak power and
using a deeper reduction ratio, than at peak (engine) torque with less
reduction ratio.


--
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.

On 04/04/2016 11:07, Dave Plowman (News) wrote:


Adding in drag etc is simply attempting to move the goalposts yet again.
Drag depends on speed. And that is irrelevant to the discussion.


If you are trying to maximise acceleration, drag is highly relevant.

If you simply want to maximise thrust at the wheels, it isn't.

But the force which actually accelerates the car is the *difference*
between the thrust at the wheels and the aerodynamic drag.

That's why every car has a maximum speed - when it reaches the point
where the drag equals the maximum thrust available so there's nothing
left to accelerate it any more.

And you may care to reflect on why it is that the maximum speed
invariably coincides with the engine's maximum *power* output in an
appropriate gear - not at its max torque point.
--
Cheers,
Roger
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checked.

In article ,
Roger Mills wrote:
No it's ********. You need to maximise the torque. Not power.

You need to maximise the torque at the *wheels*. Don't forget, there's a
gearbox between the engine and the wheels. As you keep reminding us, a
gearbox magnifies the torque.

Yes it does. But throughout the range of engine revs in that gear.

You seem to be wanting to pick the torque produced by the engine at peak
BHP in one gear and compare it to the torque produced in another gear.

But that comes at the expense of speed. So
- as should be obvious - you need a higher engine speed to maintain a
given road speed in a low gear than you would in a higher gear. And when
the engine is at its max power point you get the highest available
product of output speed and torque - which is what you want.

Are you trying to say acceleration is uniform at all points in every gear?



That's what I've been saying all along. That's why I gave
the example of using a continuously variable transmission to hold the
engine at its max power (*NOT* max torque) speed as the car accelerates.

Care to explain why a CVT holds the engine at maximum torque, then?


I'm not aware that it does. If I were to design one, it certainly wouldn't!

But then you're obviously not into car design. ;-)

It's obvious when you consider that power = thrust x speed. At any given
speed, the higher the power the higher the thrust.

I've no idea what you mean by 'thrust' That's something usually associated
with a jet engine. Power is a function of torque and RPM. And the higher
the power does *not* mean the higher the torque.


Newton's first law! A body remains at rest or moves at a constant speed
in a straight line unless acted upon by "forces".

And the 'force' in this case is torque.

In order to accelerate a car, you need an external force. That force is
imparted to the car through the contact patch. The torque imparted on
the wheels through the transmission manifests itself as a force at the
contact patch which tries to push the road backwards. But the road
usually wins, and pushes the car forwards instead. *That* is the thrust
to which I was referring.

--
*Sleep with a photographer and watch things develop

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

In article ,
The Natural Philosopher wrote:
And the point you and plowperson refuse to accept is that you will get
more thrust at the contact patch by running the engine at peak power and
using a deeper reduction ratio, than at peak (engine) torque with less
reduction ratio.

Pleas don't talk for me Turnip. You have enough trouble talking for
yourself. Especially when you've *totally* missed my point.

Only you could be so stupid as to think I don't know that a gearbox
multiplies torque. You, on the other hand, appear not to understand how
power relates to torque.

--
*If work is so terrific, how come they have to pay you to do it?

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

In article ,
Roger Mills wrote:
On 04/04/2016 11:07, Dave Plowman (News) wrote:


Adding in drag etc is simply attempting to move the goalposts yet
again. Drag depends on speed. And that is irrelevant to the discussion.


If you are trying to maximise acceleration, drag is highly relevant.

From 0-10 mph? Doubt you could measure it. From 150-160 mph it could be
very significant. Depending on the design of the vehicle. Which you
haven't specified.

If you simply want to maximise thrust at the wheels, it isn't.

No such things as thrust at the wheels. It's a term used for jet engines.

But the force which actually accelerates the car is the *difference*
between the thrust at the wheels and the aerodynamic drag.

You're making this up as you go along...

That's why every car has a maximum speed - when it reaches the point
where the drag equals the maximum thrust available so there's nothing
left to accelerate it any more.

And you may care to reflect on why it is that the maximum speed
invariably coincides with the engine's maximum *power* output in an
appropriate gear - not at its max torque point.

None of which has any bearing on the point.

--
*Born free...Taxed to death.

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

On 04/04/2016 14:27, The Natural Philosopher wrote:
On 04/04/16 14:13, Roger Mills wrote:
On 03/04/2016 10:41, Roger Mills wrote:
On 02/04/2016 22:57, The Natural Philosopher wrote:
On 02/04/16 22:53, Roger Mills wrote:
On 02/04/2016 18:11, The Natural Philosopher wrote:
On 02/04/16 18:01, Roger Mills wrote:
On 02/04/2016 14:15, Dave Plowman (News) wrote:


As I said before, some seem totally incapable of understanding a
very
simple and basic condition.


I think we agree on THAT! What we DON'T agree on is who those people
ARE!!!!

You and Dave, basically.



Pray what simple and basic condition have *I* failed to understand?

Gearboxes. The relationship between power torque acceleration and
speed.
Basic mechanical engineering.
Take your pick.


Rubbish! I challenge to you quote anything I wrote which backs up your
statement.

Your silence is deafening, Mr "Philosopher". I'm still waiting for your
abject apology!

Sorry. I didn't see the previous post.

The mere fact that you agree with D plowman is sufficient evidence. I
rest my case.



BUT I *DON'T* FOR GOD'S SAKE!!!! Why on earth do you think I do?

--
Cheers,
Roger
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checked.

On 04/04/2016 14:33, The Natural Philosopher wrote:


And the point you and plowperson refuse to accept is that you will get
more thrust at the contact patch by running the engine at peak power and
using a deeper reduction ratio, than at peak (engine) torque with less
reduction ratio.


Mr Plowman refuses to accept that. I don't and never have. I've always
said you need to run the engine at peak power.

Again I challenge you to quote anything I've said which suggests otherwise.
--
Cheers,
Roger
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On 04/04/2016 14:47, Dave Plowman (News) wrote:


You seem to be wanting to pick the torque produced by the engine at peak
BHP in one gear and compare it to the torque produced in another gear.

But that is precisely what one does when changing up through the gears.
Go up to max power and beyond and then change to the next gear - which
will give you more input torque but less output torque.



Are you trying to say acceleration is uniform at all points in every gear?

Of course not. It largely follows the torque curve (minus the drag!) in
each gear, and then there's a step change (downwards!) when you change
to the next gear.


Care to explain why a CVT holds the engine at maximum torque, then?

I'm not aware that it does. If I were to design one, it certainly wouldn't!

But then you're obviously not into car design. ;-)

When did you last design a car? The work we did a Rover a few decades
ago on the Perbury transmission (a derivative of the earlier Austin
Hayes transmission) certainly aimed to run the engine at max power for
max acceleration. I've no idea what Daf did with the belt drive system.



Newton's first law! A body remains at rest or moves at a constant speed
in a straight line unless acted upon by "forces".

And the 'force' in this case is torque.


Force and torque don't even have the same dimensions!! Read what I said
below.


In order to accelerate a car, you need an external force. That force is
imparted to the car through the contact patch. The torque imparted on
the wheels through the transmission manifests itself as a force at the
contact patch which tries to push the road backwards. But the road
usually wins, and pushes the car forwards instead. *That* is the thrust
to which I was referring.



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

On 04/04/2016 14:57, Dave Plowman (News) wrote:
In ,
Roger wrote:


If you simply want to maximise thrust at the wheels, it isn't.

No such things as thrust at the wheels. It's a term used for jet engines.

In that case, please explain how a car gets accelerated by a horizontal
force. It certainly isn't pushed along by its exhaust gases!


But the force which actually accelerates the car is the *difference*
between the thrust at the wheels and the aerodynamic drag.

You're making this up as you go along...



Sorry - if you don't understand that, there's really no point in
discussing this any further.
--
Cheers,
Roger
____________
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checked.

On 04/04/2016 14:33, The Natural Philosopher wrote:
On 04/04/16 14:29, Roger Mills wrote:
You need to maximise the torque at the *wheels*. Don't forget, there's a
gearbox between the engine and the wheels. As you keep reminding us, a
gearbox magnifies the torque. But that comes at the expense of speed. So
- as should be obvious - you need a higher engine speed to maintain a
given road speed in a low gear than you would in a higher gear. And when
the engine is at its max power point you get the highest available
product of output speed and torque - which is what you want.

snip
And the point you and plowperson refuse to accept is that you will get
more thrust at the contact patch by running the engine at peak power and
using a deeper reduction ratio, than at peak (engine) torque with less
reduction ratio.

Roger has it right. I misunderstood him.

Andy

On 04/04/2016 18:59, Roger Mills wrote:

Of course not. It largely follows the torque curve (minus the drag!) in
each gear, and then there's a step change (downwards!) when you change
to the next gear.

I thought the idea was to run so far past peak power that when you
changed up you were at the same power output the other side of the peak?
So no steps?

Andy

On 04/04/2016 19:04, Roger Mills wrote:
Sorry - if you don't understand that, there's really no point in
discussing this any further.

I already said that!

Andy

On 04/04/2016 21:42, Vir Campestris wrote:
On 04/04/2016 18:59, Roger Mills wrote:

Of course not. It largely follows the torque curve (minus the drag!) in
each gear, and then there's a step change (downwards!) when you change
to the next gear.

I thought the idea was to run so far past peak power that when you
changed up you were at the same power output the other side of the peak?
So no steps?

Andy

That would be the ideal, and may be achievable if you have a lot of
closely spaced gears. Otherwise you're likely to reach valve bounce or,
in the case of a diesel, hit the governor before reaching the point
where the next gear up will allow the engine to produce the same amount
of power.

In all the calculations I did when I was doing this for a living -
albeit a few decades ago - the next gear up always dropped you further
down the power curve. When doing a practical road test, you could
counter that to some extent by not letting the engine revs drop during
the gear-change so that you got an inertial 'kick' when you let the
clutch in.

That reminds me of one factor which we had to include in performance
calculations which hasn't been discussed here - namely the effect of the
engine's own moment of inertia. In a low gear, quite of lot of engine
torque is used up accelerating the engine itself - reducing the amount
available for accelerating the vehicle. The "effective mass" of the
engine, which was different for each gear, had to be added to the
vehicle mass when calculating acceleration.
--
Cheers,
Roger
____________
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On 04/04/16 18:05, Roger Mills wrote:
On 02/04/2016 14:15, Dave Plowman (News) wrote:


As I said before, some seem totally incapable of understanding a
very
simple and basic condition.


I think we agree on THAT! What we DON'T agree on is who those people
ARE!!!!

On 02/04/2016 14:15, Dave Plowman (News) wrote:


As I said before, some seem totally incapable of understanding a
very
simple and basic condition.


I think we agree on THAT! What we DON'T agree on is who those people
ARE!!!!


--
Future generations will wonder in bemused amazement that the early
twenty-first centurys developed world went into hysterical panic over a
globally average temperature increase of a few tenths of a degree, and,
on the basis of gross exaggerations of highly uncertain computer
projections combined into implausible chains of inference, proceeded to
contemplate a rollback of the industrial age.

Richard Lindzen

On 04/04/16 21:42, Vir Campestris wrote:
On 04/04/2016 18:59, Roger Mills wrote:

Of course not. It largely follows the torque curve (minus the drag!) in
each gear, and then there's a step change (downwards!) when you change
to the next gear.

I thought the idea was to run so far past peak power that when you
changed up you were at the same power output the other side of the peak?
So no steps?


That is PROBABLY optimum for uniform power loss with RPM each side of
the peak. #
But a lot of performance engines develop peak power at peak RPM and are
limited so as not to go beyond that point.

Andy


--
Future generations will wonder in bemused amazement that the early
twenty-first centurys developed world went into hysterical panic over a
globally average temperature increase of a few tenths of a degree, and,
on the basis of gross exaggerations of highly uncertain computer
projections combined into implausible chains of inference, proceeded to
contemplate a rollback of the industrial age.

Richard Lindzen

On 04/04/16 23:09, Roger Mills wrote:
On 04/04/2016 21:42, Vir Campestris wrote:
On 04/04/2016 18:59, Roger Mills wrote:

Of course not. It largely follows the torque curve (minus the drag!) in
each gear, and then there's a step change (downwards!) when you change
to the next gear.

I thought the idea was to run so far past peak power that when you
changed up you were at the same power output the other side of the peak?
So no steps?

Andy

That would be the ideal, and may be achievable if you have a lot of
closely spaced gears. Otherwise you're likely to reach valve bounce or,
in the case of a diesel, hit the governor before reaching the point
where the next gear up will allow the engine to produce the same amount
of power.

In all the calculations I did when I was doing this for a living -
albeit a few decades ago - the next gear up always dropped you further
down the power curve. When doing a practical road test, you could
counter that to some extent by not letting the engine revs drop during
the gear-change so that you got an inertial 'kick' when you let the
clutch in.

That reminds me of one factor which we had to include in performance
calculations which hasn't been discussed here - namely the effect of the
engine's own moment of inertia. In a low gear, quite of lot of engine
torque is used up accelerating the engine itself - reducing the amount
available for accelerating the vehicle. The "effective mass" of the
engine, which was different for each gear, had to be added to the
vehicle mass when calculating acceleration.

Balanced lightened flywheel/crank lightened pinions..BTDTGTTS


--
Bureaucracy defends the status quo long past the time the quo has lost
its status.

Laurence Peter

On 04/04/2016 23:43, The Natural Philosopher wrote:
On 04/04/16 18:05, Roger Mills wrote:
On 02/04/2016 14:15, Dave Plowman (News) wrote:


As I said before, some seem totally incapable of understanding a
very
simple and basic condition.


I think we agree on THAT! What we DON'T agree on is who those people
ARE!!!!

On 02/04/2016 14:15, Dave Plowman (News) wrote:


As I said before, some seem totally incapable of understanding a
very
simple and basic condition.


I think we agree on THAT! What we DON'T agree on is who those people
ARE!!!!



Is that the best you can find in order to assert that I agree with Mr
Plowman?

The *only* thing we agree on is that "some people" are incapable of
understanding simple basic principles. I guess that even you would agree
on that.

What we *don't* agree on is who those people are. Mr Plowman almost
certainly - erroneously - puts me in that category, and I definitely put
*him* in it.

I'm afraid you'll have to do better than that! Your apology is still
awaited.
--
Cheers,
Roger
____________
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checked.

On 05/04/16 08:14, Roger Mills wrote:
On 04/04/2016 23:43, The Natural Philosopher wrote:
On 04/04/16 18:05, Roger Mills wrote:
On 02/04/2016 14:15, Dave Plowman (News) wrote:


As I said before, some seem totally incapable of understanding a
very
simple and basic condition.


I think we agree on THAT! What we DON'T agree on is who those people
ARE!!!!

On 02/04/2016 14:15, Dave Plowman (News) wrote:


As I said before, some seem totally incapable of understanding a
very
simple and basic condition.


I think we agree on THAT! What we DON'T agree on is who those people
ARE!!!!



Is that the best you can find in order to assert that I agree with Mr
Plowman?

The *only* thing we agree on is that "some people" are incapable of
understanding simple basic principles. I guess that even you would agree
on that.

What we *don't* agree on is who those people are. Mr Plowman almost
certainly - erroneously - puts me in that category, and I definitely put
*him* in it.

I'm afraid you'll have to do better than that! Your apology is still
awaited.

well if you that is the case, sorry. OK?


--
Those who want slavery should have the grace to name it by its proper
name. They must face the full meaning of that which they are advocating
or condoning; the full, exact, specific meaning of collectivism, of its
logical implications, of the principles upon which it is based, and of
the ultimate consequences to which these principles will lead. They must
face it, then decide whether this is what they want or not.

Ayn Rand.

In article ,
Roger Mills wrote:
You seem to be wanting to pick the torque produced by the engine at
peak BHP in one gear and compare it to the torque produced in another
gear.

But that is precisely what one does when changing up through the gears.
Go up to max power and beyond and then change to the next gear - which
will give you more input torque but less output torque.

Which as precisely nothing to do with the original point. Which was at
which point on an engine's rev range you get the best acceleration.

--
*A bartender is just a pharmacist with a limited inventory.

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

Just to see if I was missing something that others found so obvious, I
asked this question on a forum designated to engine building and tuning,
etc.

'At what point on an engines output do you get maximum acceleration?'

And the answers were near unanimous. Peak torque.

I'll take the views of those guys over the bar room mechanics here any day.

--
*Never miss a good chance to shut up.*

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

In article ,
Roger Mills wrote:
Care to explain why a CVT holds the engine at maximum torque, then?

I'm not aware that it does. If I were to design one, it certainly
wouldn't!

But then you're obviously not into car design. ;-)

When did you last design a car? The work we did a Rover a few decades
ago on the Perbury transmission (a derivative of the earlier Austin
Hayes transmission) certainly aimed to run the engine at max power for
max acceleration.

A very successful concept, obviously.

Read the first paragraph of this. ;-)

http://www.austinmemories.com/styled-23/index.html


I've no idea what Daf did with the belt drive system.

I've told you.

--
*Remember: First you pillage, then you burn.

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

On 05/04/2016 10:43, The Natural Philosopher wrote:
On 05/04/16 08:14, Roger Mills wrote:
On 04/04/2016 23:43, The Natural Philosopher wrote:
On 04/04/16 18:05, Roger Mills wrote:
On 02/04/2016 14:15, Dave Plowman (News) wrote:


As I said before, some seem totally incapable of understanding a
very
simple and basic condition.


I think we agree on THAT! What we DON'T agree on is who those people
ARE!!!!

On 02/04/2016 14:15, Dave Plowman (News) wrote:


As I said before, some seem totally incapable of understanding a
very
simple and basic condition.


I think we agree on THAT! What we DON'T agree on is who those people
ARE!!!!



Is that the best you can find in order to assert that I agree with Mr
Plowman?

The *only* thing we agree on is that "some people" are incapable of
understanding simple basic principles. I guess that even you would agree
on that.

What we *don't* agree on is who those people are. Mr Plowman almost
certainly - erroneously - puts me in that category, and I definitely put
*him* in it.

I'm afraid you'll have to do better than that! Your apology is still
awaited.

well if you that is the case, sorry. OK?



Accepted - thanks!
--
Cheers,
Roger
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On 05/04/2016 10:58, Dave Plowman (News) wrote:
In ,
Roger wrote:

When did you last design a car? The work we did a Rover a few decades
ago on the Perbury transmission (a derivative of the earlier Austin
Hayes transmission) certainly aimed to run the engine at max power for
max acceleration.

A very successful concept, obviously.


The idea was good but oil technology was not sufficiently developed in
the 1930's to make it work reliably without wearing out the rubbing parts.

Read the first paragraph of this. ;-)

http://www.austinmemories.com/styled-23/index.html


I presume you're referring to the bit where it says "method of
transmitting power at a variable speed, but at the maximum torque".

You'll note that it's not specific as to whether it's talking about
input or output torque.

Later in the article it talks about using a high ratio in order to run
the engine at low speed and high torque for maximum fuel efficiency.
This makes perfect sense, but is irrelevant as far as any discussion
about acceleration is concerned because nowhere does it mention
acceleration - only steady state.
--
Cheers,
Roger
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checked.

On 05/04/2016 10:52, Dave Plowman (News) wrote:
Just to see if I was missing something that others found so obvious, I
asked this question on a forum designated to engine building and tuning,
etc.

'At what point on an engines output do you get maximum acceleration?'

And the answers were near unanimous. Peak torque.

I'll take the views of those guys over the bar room mechanics here any day.


If they meant maximum *engine* acceleration, I'd have to agree with
them. But if they meant maximum *vehicle* acceleration, they clearly
haven't understood the question!
--
Cheers,
Roger
____________
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checked.

On 05/04/2016 10:46, Dave Plowman (News) wrote:
In ,
Roger wrote:
You seem to be wanting to pick the torque produced by the engine at
peak BHP in one gear and compare it to the torque produced in another
gear.

But that is precisely what one does when changing up through the gears.
Go up to max power and beyond and then change to the next gear - which
will give you more input torque but less output torque.

Which as precisely nothing to do with the original point. Which was at
which point on an engine's rev range you get the best acceleration.


The very first post which started this thread *actually* said the following:

"Q1: If an engine is capable of a peak torque of 400nM, what is the
force available at the wheels at a speed of 10m/S?"

.. . . which is impossible to answer without knowing anything about the
gearing - and which makes no mention whatsoever about acceleration.

It has morphed - as many threads do - into a discussion about something
which is not directly related to the original subject.

And the fact remains that - at any given speed - the highest
instantaneous rate of change in speed (acceleration) is obtained by
maximising the amount of power transmitted to the wheels. Simple laws of
Physics!
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On 05/04/16 12:37, Roger Mills wrote:
On 05/04/2016 10:46, Dave Plowman (News) wrote:
In ,
Roger wrote:
You seem to be wanting to pick the torque produced by the engine at
peak BHP in one gear and compare it to the torque produced in another
gear.

But that is precisely what one does when changing up through the gears.
Go up to max power and beyond and then change to the next gear -
which
will give you more input torque but less output torque.

Which as precisely nothing to do with the original point. Which was at
which point on an engine's rev range you get the best acceleration.


The very first post which started this thread *actually* said the
following:

"Q1: If an engine is capable of a peak torque of 400nM, what is the
force available at the wheels at a speed of 10m/S?"

. . . which is impossible to answer without knowing anything about the
gearing - and which makes no mention whatsoever about acceleration.

It has morphed - as many threads do - into a discussion about something
which is not directly related to the original subject.

And the fact remains that - at any given speed - the highest
instantaneous rate of change in speed (acceleration) is obtained by
maximising the amount of power transmitted to the wheels. Simple laws of
Physics!

It is all very reminiscent of the 'fly inside the cabin of a 707 and how
fast is it flying' malarkey.


--
The theory of Communism may be summed up in one sentence: Abolish all
private property.

Karl Marx

In article ,
Roger Mills wrote:
http://www.austinmemories.com/styled-23/index.html


I presume you're referring to the bit where it says "method of
transmitting power at a variable speed, but at the maximum torque".

You'll note that it's not specific as to whether it's talking about
input or output torque.

Good grief. ;-)

--
*When the going gets tough, the tough take a coffee break *

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

In article ,
Roger Mills wrote:
On 05/04/2016 10:52, Dave Plowman (News) wrote:
Just to see if I was missing something that others found so obvious, I
asked this question on a forum designated to engine building and
tuning, etc.

'At what point on an engines output do you get maximum acceleration?'

And the answers were near unanimous. Peak torque.

I'll take the views of those guys over the bar room mechanics here any
day.


If they meant maximum *engine* acceleration, I'd have to agree with
them. But if they meant maximum *vehicle* acceleration, they clearly
haven't understood the question!

No, they understood it perfectly. Plenty on here don't, though. Those who
don't understand BHP and torque. Must admit to being amazed how many
don't.

--
*Shin: a device for finding furniture in the dark *

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

In article ,
Roger Mills wrote:
On 05/04/2016 10:46, Dave Plowman (News) wrote:
In ,
Roger wrote:
You seem to be wanting to pick the torque produced by the engine at
peak BHP in one gear and compare it to the torque produced in another
gear.

But that is precisely what one does when changing up through the
gears. Go up to max power and beyond and then change to the next gear
- which will give you more input torque but less output torque.

Which as precisely nothing to do with the original point. Which was at
which point on an engine's rev range you get the best acceleration.


The very first post which started this thread *actually* said the
following:

"Q1: If an engine is capable of a peak torque of 400nM, what is the
force available at the wheels at a speed of 10m/S?"

. . . which is impossible to answer without knowing anything about the
gearing - and which makes no mention whatsoever about acceleration.

I take it you don't remember the original thread some weeks ago? it was
obvious that Vir Campestris was attempting to prove he was now right about
that.

It has morphed - as many threads do - into a discussion about something
which is not directly related to the original subject.

And the fact remains that - at any given speed - the highest
instantaneous rate of change in speed (acceleration) is obtained by
maximising the amount of power transmitted to the wheels. Simple laws of
Physics!

Sigh. Not thrust now? Power is measured in BHP. So you are perfectly sure
of this? Because you're wrong. It happens at maximum torque.

--
*Of course I'm against sin; I'm against anything that I'm too old to enjoy.

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

"Roger Mills" wrote in message
...

And the fact remains that - at any given speed - the highest instantaneous rate of
change in speed (acceleration) is obtained by maximising the amount of power
transmitted to the wheels. Simple laws of Physics!

Surely maximising the amount of power transmitted to the wheels
to change the speed from say 1 mph to say 5mph would simply
result in wheelspin. As many boy racers at traffic lights know
to their cost, never mind many stars in reasonably prices cars*.
And the same would presumably also apply in wet or icy conditions*
at much higher speeds

Not that the same doesn't apply equally well to torque.



michael adams

*Top Gear
*Ice Road Truckers

....

"Tim Streater" wrote in message
.. .
In article , michael
adams wrote:

"Roger Mills" wrote in message
...

And the fact remains that - at any given speed - the highest instantaneous
rate of change in speed (acceleration) is obtained by maximising the amount of power
transmitted to the wheels. Simple laws of Physics!

Surely maximising the amount of power transmitted to the wheels
to change the speed from say 1 mph to say 5mph would simply
result in wheelspin.

Doesn't necessarily follow. Studded tires come to mind.

But depending on weight distribultion, and assuming the studded tires
dont simply carve a big hole in the road surface, all that that might achieve
might be to send the front of the car into the air, if not flip it over completely.

And overal studded tires would be a specal case dependent on an
optimum road surface, and optimum weigh distribution and would only
be applicable up to a certain speed.


michael adams

....

On 05/04/2016 14:54, Dave Plowman (News) wrote:
In ,
Roger wrote:


If they meant maximum *engine* acceleration, I'd have to agree with
them. But if they meant maximum *vehicle* acceleration, they clearly
haven't understood the question!

No, they understood it perfectly. Plenty on here don't, though. Those who
don't understand BHP and torque. Must admit to being amazed how many
don't.


Get yourself a large mirror!
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On 05/04/2016 14:58, Dave Plowman (News) wrote:
In ,
Roger wrote:
On 05/04/2016 10:46, Dave Plowman (News) wrote:


The very first post which started this thread *actually* said the
following:

"Q1: If an engine is capable of a peak torque of 400nM, what is the
force available at the wheels at a speed of 10m/S?"

. . . which is impossible to answer without knowing anything about the
gearing - and which makes no mention whatsoever about acceleration.

I take it you don't remember the original thread some weeks ago? it was
obvious that Vir Campestris was attempting to prove he was now right about
that.

So are you telling me that everything you've written relates to
*another* thread rather than this one? I can only cope with one thread
at a time!


And the fact remains that - at any given speed - the highest
instantaneous rate of change in speed (acceleration) is obtained by
maximising the amount of power transmitted to the wheels. Simple laws of
Physics!

Sigh. Not thrust now? Power is measured in BHP. So you are perfectly sure
of this? Because you're wrong. It happens at maximum torque.


What I said is correct. If you maximise power at a given speed you also
maximise thrust at that speed since thrust = power / speed. You are also
maximising the drive-shaft torque at that speed. Where we differ is that
you say this coincides with engine max torque and I - and everyone else
as far as I can ascertain - says that this coincides with max engine
*power*. Do the sums with some actual numbers!
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On 05/04/2016 15:35, michael adams wrote:
"Roger wrote in message
...

And the fact remains that - at any given speed - the highest instantaneous rate of
change in speed (acceleration) is obtained by maximising the amount of power
transmitted to the wheels. Simple laws of Physics!

Surely maximising the amount of power transmitted to the wheels
to change the speed from say 1 mph to say 5mph would simply
result in wheelspin. As many boy racers at traffic lights know
to their cost, never mind many stars in reasonably prices cars*.
And the same would presumably also apply in wet or icy conditions*
at much higher speeds

Not that the same doesn't apply equally well to torque.

Well yes, of course. But I think we're assuming we have a dry road with
plenty of adhesion.

[I did in fact cite icy conditions at one point when trying to explain
to My Plowman what I meant by "thrust"].
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

"Tim Streater" wrote in message
.. .
In article , michael
adams wrote:

"Tim Streater" wrote in message
...
In article , michael
adams wrote:

"Roger Mills" wrote in message
...

And the fact remains that - at any given speed - the highest instantaneous
rate of change in speed (acceleration) is obtained by maximising the
amount of power transmitted to the wheels. Simple laws of Physics!

Surely maximising the amount of power transmitted to the wheels
to change the speed from say 1 mph to say 5mph would simply
result in wheelspin.

Doesn't necessarily follow. Studded tires come to mind.

But depending on weight distribultion, and assuming the studded tires
dont simply carve a big hole in the road surface, all that that might achieve
might be to send the front of the car into the air, if not flip it over
completely.

Front wheel drive.

And overal studded tires would be a specal case dependent on an
optimum road surface, and optimum weigh distribution and would only
be applicable up to a certain speed.

All cases are special cases and depend on all the factors you mention.

What was being proposed, was a general principle.

If all cases were special cases, then there would be little point in formulating
general principles at all, would there ?



michael adams

....

On 05/04/2016 12:37, Roger Mills wrote:
The very first post which started this thread *actually* said the
following:

"Q1: If an engine is capable of a peak torque of 400nM, what is the
force available at the wheels at a speed of 10m/S?"

. . . which is impossible to answer without knowing anything about the
gearing - and which makes no mention whatsoever about acceleration.

The whole point was that it's impossible to say. Torque on its own is
useless - you need revs too, and that means it's power. Force times speed.

Andy

"Roger Mills" wrote in message
...
On 05/04/2016 15:35, michael adams wrote:
"Roger wrote in message
...

And the fact remains that - at any given speed - the highest instantaneous rate of
change in speed (acceleration) is obtained by maximising the amount of power
transmitted to the wheels. Simple laws of Physics!

Surely maximising the amount of power transmitted to the wheels
to change the speed from say 1 mph to say 5mph would simply
result in wheelspin. As many boy racers at traffic lights know
to their cost, never mind many stars in reasonably prices cars*.
And the same would presumably also apply in wet or icy conditions*
at much higher speeds

Not that the same doesn't apply equally well to torque.

Well yes, of course. But I think we're assuming we have a dry road with plenty of
adhesion.

Indeed, but how would those two conditions prevent wheelspin between
say 1mph and 5mph ?


[I did in fact cite icy conditions at one point when trying to explain to My Plowman
what I meant by "thrust"].


On one episode of "Ice Road Truckers" Lisa Kelly gave a lift to a
lady from the transportation dept. The latter was surpised how
fast the truck was going over clearly slippery conditions -
the roads were permanent ice; much faster than she would
dare drive in her car. Lisa explained that the greater weight
of the truck and trailer allowed her to drive that much faster.
They never seem to ever speak about braking distances
on IRT for some reason. No mention of thrust from Lisa though.


michael adams

....