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From: Adrian on 29 Sep 2009 15:30
Conor <conor(a)gmx.co.uk> gurgled happily, sounding much like they were
>> The Capri 2l doesn't have 130bhp.
> Correct. However one with a Kent FR31 camshaft, 4-2-1 exhaust manifold,
> K&N air filter and a rejetted carb does.
Would that be a real figure from a dyno? Or a calculation from the
If it's from a dyno, I'm presuming it's a back-calculation to the
flywheel from a wheel figure. What's the wheel figure?
From: DavidR on 29 Sep 2009 15:33
"The Debacler" <jameswoolford2000(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'?
How long is a piece of string?
> I seem to remember the acceleration from a friends Vauxhall cavalier 2.0
> 16v was when I first noticed it(which was about 130bhp).
To put things in perspective, you are standing on a planet delivering a
force on your body equivalent to an acceleration of 1g. When you lie down on
your bed the force on your back is significantly higher than any car can
deliver. It takes a 0-60 time of 2.8 seconds to produce 1g which, for road
vehicles, is pretty much the private domain of motorbikes. A 130bhp Cavalier
averages about 0.3g getting to 60 but may double that for a few moments.
The only time you are likely to experience sustained 1g in a car is under
> 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. How it is achieved is largely irrelevant.
In a dynamic sense, cars are pretty boring things, really, and the
impression of speed from a rapidly driven car comes more from the visual
effect of scenery flashing past than from sustained forces. If you want a
decent sense of acceleration, go to a theme park or hire an aeroplane for a
demonstration of some basic manoeuvers - and 3g is fairly basic.
From: Mike Barnes on 29 Sep 2009 17:22
In uk.rec.driving, Conor wrote:
>In article <xjSK6VQq2bwKFwm1(a)g52lk5g23lkgk3lk345g.invalid>, Mike Barnes
>> In uk.rec.driving, Conor wrote:
>> >In article <VvdDJeDWgTwKFwii(a)g52lk5g23lkgk3lk345g.invalid>, Mike Barnes
>> >> Note that the word "torque" doesn't figure in any of this.
>> >Shame because its what makes the difference.
>> The best interpretation I can put on that is that what you call "torque"
>> is not what a physicist calls "torque".
>I did O level physics. I did O level Control Technology, both of which
>cover what torque is. I was taught it was the measure of a force's
>torsion and rotation about an axis, calculated as torque=force x radius.
Excellent, so you do know what "torque" is.
You also presumably know that you can vary torque by adding a gearbox.
If you have an engine that provides 200 ft-lbs, you can double it,
treble it, get ten times as much torque. Just add a 2:1, 3:1, 10:1
gearbox. No extra fuel, no energy required, just tack on a few cogs and
you've got virtually any amount of torque you like.
2000 ft-lbs? No problem sir. Are you sure you don't want more?
But it won't improve your car's acceleration.
From: Conor on 29 Sep 2009 19:12
In article <7if5iqF31jdjoU3(a)mid.individual.net>, Adrian says...
> Conor <conor(a)gmx.co.uk> gurgled happily, sounding much like they were
> >> The Capri 2l doesn't have 130bhp.
> > Correct. However one with a Kent FR31 camshaft, 4-2-1 exhaust manifold,
> > K&N air filter and a rejetted carb does.
> Would that be a real figure from a dyno? Or a calculation from the
> If it's from a dyno, I'm presuming it's a back-calculation to the
> flywheel from a wheel figure. What's the wheel figure?
AFAIR, it was 110 or thereabouts.
I'm not prejudiced. I hate everybody equally.
From: Mike Barnes on 29 Sep 2009 17:48
In uk.rec.driving, Mark wrote:
>When we are comparing normal mid-sized road going cars going at a
>set speed and the same gears, there's not a whole heap of difference between
>ratios and wheel sizes. Certainly any difference in the maximum
>*instantanious* feel of the acceleration would be mainly down to the
>respective torque of the engines.
But it makes no sense to compare the acceleration of petrol and diesel
cars in the same gear. All other things being equal, you can make
whichever one you like look better by a suitable choice of gear.