Getting pushed back in your seat
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From: Peter Hill on 29 Sep 2009 03:06 On Mon, 28 Sep 2009 22:53:42 +0100, Conor <conor(a)gmx.co.uk> wrote: >In article <bl12c59opbj8nhjp1egdipukm2gr3p7f2d(a)4ax.com>, Peter Hill >says... >> >> 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. >> >I have a 2L Capri. It has 130BHP, weighs 1098kg. It has roughly 100lb/ft >torque. > >I have a 2L Mondeo TDCi. It has 130BHP, weighs approx 1500kg. It has >roughly 244lb/ft. > >The Mondeo absolutely thrashes the Capri on 30-70MPH acceleration >despite weighing nearly 50% more. Is that redlining though the gears or in top? >Explain. I though I had. Find me dyno plots or at least the rpm those peak torque and power figures are at + redline rpm. Gear ratios, Final drive ratio, Tyre sizes. Or at least mph/1000rpm in top for each. Mph/1000rpm for lower gears will permit cascades to be drawn showing optimum gear changes and show how to get the Capri to deliver a spanking to the TDCi (hint power not torque). For full analysis to max speed in top I also need Cd and frontal area, or top speed (not speedo indicated). I've got to admit the 2.0TDCi is at it's best in top gear between 50-70mph. As for the 2.2TDCi, I have to be in 4th to even think about it at 60-70mph. It's why Diesels suit so many people that like to drive at moderate/low rpm. The fact that Diesels become so nasty at high rpm just reinforces the fear of the redline but it's holding revs up around peak power that gives the best acceleration performances that are quoted by makers and in the press. Unfortunately the performance below peak torque of diesels is very very poor. If you feel the surge as it comes up to the peak torque you are losing a lot of performance, you should have changed down before mashing the pedal. A diesel above peak torque is only down a little bit on max acceleration by selecting the wrong gear (too high), below it loses a huge margin. Sadly all the comments about Diesels having "narrow power bands" makes me think people are feeling that pathetic torque surge. A good diesel truck doesn't have a "power band", it has a power line, max power is constant over a 1500 rpm band, like 3000 to 4500rpm, while peak torque is way down at 1500rpm. -- 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!
From: Mike Barnes on 29 Sep 2009 03:25 In uk.rec.driving, Pete M wrote: >Mike Barnes wrote: >> In uk.rec.driving, Conor wrote: >> >>> I have a 2L Capri. It has 130BHP, weighs 1098kg. It has roughly >>>100lb/ft >>> torque. >>> >>> I have a 2L Mondeo TDCi. It has 130BHP, weighs approx 1500kg. It has >>> roughly 244lb/ft. >>> >>> The Mondeo absolutely thrashes the Capri on 30-70MPH acceleration >>> despite weighing nearly 50% more. >>> >>> Explain. >> You haven't given enough information for anything other than a >>guess, >> but my guess would be that the difference is largely explained by two >> things: >> 1 The diesel's power is available over a wider range of revs. You >> presumably quote peak power, which applies at only one speed. The >> petrol engine's power will fall off very quickly either side of the >> peak revs, whereas the diesel engine's won't. > >Diesel power bands are notoriously narrow, especially compared to that >of any good petrol engine. Turbo diesels have even narrower useable >power bands. Yes but I wasn't talking about petrol or diesel engines in general, I was referring to the two examples described by Conor, over quite a narrow speed range. Any specific information you can provide would be welcome. >> 2 In a petrol-driven car, the driver often can't be arsed to change >> down, but in the diesel car he doesn't have to. With a petrol engine >> the power is only available at higher revs, hence the need to change >> down. >Try something with a proper petrol engine. Define "proper". >> 3 (OK, I can't count). The Capri is knackered. :-) >> Note that the word "torque" doesn't figure in any of this. > >You're another diesel apologist, I can somehow sense it. Actually you're wrong. I've owned only performance cars since 1981 (Golf GTi, Audi Quattro, etc, don't sneer), and I intend to keep it that way. But I dislike the motoring press's ignorant trumpeting of "torque" as if it were some magic new ingredient. Torque on its own is meaningless. Power is what matters, along with weight. Not maximum power at some other speed, but the power *actually* being produced by the engine. -- Mike Barnes
From: Bod on 29 Sep 2009 03:36 Peter Hill wrote: > On Mon, 28 Sep 2009 22:53:42 +0100, Conor <conor(a)gmx.co.uk> wrote: > >> In article <bl12c59opbj8nhjp1egdipukm2gr3p7f2d(a)4ax.com>, Peter Hill >> says... >>> 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 _______________________________________________________________________ In many of my cars, girls have been pushed back in their seat.......and that was when the engine was turned off. Bod
From: Mike Barnes on 29 Sep 2009 03:56 In uk.rec.driving, Conor wrote: >In article <VvdDJeDWgTwKFwii(a)g52lk5g23lkgk3lk345g.invalid>, Mike Barnes >says... > >> 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". -- Mike Barnes
From: The Debacler on 29 Sep 2009 04:16
On 29 Sep, 09:05, Conor <co...(a)gmx.co.uk> wrote: > In article <xjSK6VQq2bwKF...(a)g52lk5g23lkgk3lk345g.invalid>, Mike Barnes > says... > > > > > In uk.rec.driving, Conor wrote: > > >In article <VvdDJeDWgTwKF...(a)g52lk5g23lkgk3lk345g.invalid>, Mike Barnes > > >says... > > > >> 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.. > > Perhaps you'd care to enlighten me as to what the difference is. > > -- > Conorwww.notebooks-r-us.co.uk > I only please one person per day. Today is not your day. Tomorrow isn't > looking good either - Scott Adams Conor would you say that your mondeo gives you more of a sensation of a 'kick in the back' when you hit peak torque? Regardless of power to weight ratio. Debacler |