Prev: What are the mph settings for speed cameras?
Next: This guy was hammering it - even by my standards!
From: Bob Sherunckle on 28 Sep 2009 12:48 "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 28 Sep 2009 13:21 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 28 Sep 2009 13:23 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 28 Sep 2009 14:00 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 28 Sep 2009 15:34
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! |