From: Bob Sherunckle on

"fishman" <spammeifyoulikebutiwontreadit(a)gmail.com> wrote in message
news:54241104-8b30-4df1-aba4-f022c54796b2(a)r36g2000vbn.googlegroups.com...
On 28 Sep, 16:23, The Debacler <jameswoolford2...(a)yahoo.co.uk> wrote:
> Trying to top the poll of the most boring or stupid question..
>
> How powerful does a car need to be to �push you back in your seat� I
> seem to remember the acceleration from a friends Vauxhall cavalier 2.0
> 16v was when I first noticed it(which was about 130bhp). I guess
> higher torque causes the sensation more than higher revving lower
> torque cars? Or is it more about delivery Turbo instead of NA?

Power to weight ratio is the most important factor.


*********************************8

My GTM had 104bhp and really pushed you back in your seat.
64ft times were as good as 200bhp 4wd turbo cars, but the GTM was a mid
engined lightweight GRP monocoque.

My Locost had 127bhp, weighed around 500kg or thereabouts and certainly
pushed you back in your seat even harder.
That would also spin the driven wheels in three of the four gears if you
were a bit too keen with the throttle.

I've been in light car which has well over 500bhp / Tonne and that
obliterates both of the above.
With its around 200bhp, it re calibrates what you think you know about fast.
Acceleration really is genuinely a blur.
Weight is the enemy.


From: Mike Barnes on
In uk.rec.driving, The Debacler wrote:
>Trying to top the poll of the most boring or stupid question..

<yawn>

>How powerful does a car need to be to 'push you back in your seat' I
>seem to remember the acceleration from a friends Vauxhall cavalier 2.0
>16v was when I first noticed it(which was about 130bhp). I guess
>higher torque causes the sensation more than higher revving lower
>torque cars? Or is it more about delivery Turbo instead of NA?

The force on your body is related to the acceleration of the car and the
firmness of the seats. More power or less weight means more
acceleration. Engine torque on its own is meaningless: you make it
meaningful by factoring in the gearing, and having done that what you
have is the power.

There are also psychological effects to take into account. *All* forward
acceleration pushes you back in your seat, but you don't usually notice
it.

--
Mike Barnes
From: Nick Finnigan on
The Debacler wrote:
> Trying to top the poll of the most boring or stupid question..
>
> How powerful does a car need to be to �push you back in your seat� I
> seem to remember the acceleration from a friends Vauxhall cavalier 2.0
> 16v was when I first noticed it(which was about 130bhp). I guess
> higher torque causes the sensation more than higher revving lower
> torque cars? Or is it more about delivery Turbo instead of NA?

A sudden increase in acceleration will thump you in the back.
Maintained acceleration will keep you pushed into the seat.
From: Adrian C on
The Debacler wrote:
> Trying to top the poll of the most boring or stupid question..
>
> How powerful does a car need to be to �push you back in your seat� I
> seem to remember the acceleration from a friends Vauxhall cavalier 2.0
> 16v was when I first noticed it(which was about 130bhp). I guess
> higher torque causes the sensation more than higher revving lower
> torque cars? Or is it more about delivery Turbo instead of NA?

My standard unmodified automatic 90HP Octavia TDI does that trick on
kickdown after some cruising on A/M roads (which is for me the
entertainment factor of the beast). Passengers don't normally expect it.

--
Adrian C
From: Peter Hill on
On Mon, 28 Sep 2009 17:36:25 +0100, "Mark" <mark(a)nowhere.com> wrote:

>
>>"fishman" <spammeifyoulikebutiwontreadit(a)gmail.com> wrote in message
>>news:54241104-8b30-4df1->aba4-f022c54796b2(a)r36g2000vbn.googlegroups.com...
>>On 28 Sep, 16:23, The Debacler <jameswoolford2...(a)yahoo.co.uk> wrote:
>>> Trying to top the poll of the most boring or stupid question..
>>>
>>> How powerful does a car need to be to �push you back in your seat� I
>>> seem to remember the acceleration from a friends Vauxhall cavalier 2.0
>>> 16v was when I first noticed it(which was about 130bhp). I guess
>>> higher torque causes the sensation more than higher revving lower
>>> torque cars? Or is it more about delivery Turbo instead of NA?
>
>>Power to weight ratio is the most important factor.
>
>Torque to weight really

Bollocks not again, here comes your Physics primer.

Q: What drives a car?
A: Traction force produced at tyre contact patch, according to
Newton's law
Force = Mass x Accel, F = M x A
so Acceleration = F / M

see that's a FORCE, it's not TORQUE!

Q: What's torque?
A: By definition Torque = Force x Distance so
Accel = Torque / (Mass x Distance)

Q: What distance?
A: The tyre rolling radius.
Accel = Torque / (Mass x Rolling rad)

Which is what you should have said but you seem to have been learning
bullshit from all the moronic motoring journo's and petrolheads that
haven't got a Physics A level between. They think engine torque is
important.

Q: So what's engine torque?
A: It makes Torque at wheel = trans efficiency x final drive ratio x
gear ratio x engine torque
Accel = effy x Engine torque [1] x final drive x gear ratio / (Mass x
Rolling rad)

Q: Phew, there must be an easier way?
A: yes there is.
Power = Force x Velocity
Acceleration = effy x Power / (Mass x Velocity)

For Acceleration, Power [2] and Weight is everything. To talk about
Acceleration produced by Engine Torque you have to know tyre size and
gear ratios. Without them you know nothing about torque and
acceleration. Any such comparison indicates a lack of education.

[2] There's more bad news.
In a given gear the peak acceleration will be at about peak torque.
But unless peak torque rpm is very close to peak power there's always
a lower gear that will give better acceleration for a given road
speed. Torque = power / speed. So the peak torque quoted is quite
useless for performance. What it does do is make the car nice to drive
in everyday use on public roads where you accept a less than startling
performance for quietness and smoothness.

[2] It's really more complex than just power as it's engine power -
drag power. That's because the Force right up there at the start in
Newton's law was really Traction force - drag force. But unless very
underpowered drag isn't a major player in 0-60mph or even 1/4 mile
times for most production cars.
--
Peter Hill
Spamtrap reply domain as per NNTP-Posting-Host in header
Can of worms - what every fisherman wants.
Can of worms - what every PC owner gets!