Getting pushed back in your seat

Is that redlining though the gears or in top?

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.

Reply to
Peter Hill
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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.

Define "proper".

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.

Reply to
Mike Barnes

Not on any diesel with a turbo. Powerband of the Capri is over more than the entire rev range of the Mondeo from tickover to redline.

The Capri has a Kent FR31 camshaft in. Powerband is from 2000-6000RPM. Changing down time doesn't factor into it at all.

174,000 with full service history. Original engine and even with 174k on, 1000 miles after the last service you can dip the engine oil and it is still completely clear and devoid of muck.

Shame because its what makes the difference.

Reply to
Conor

Talking of which, I don't recall any progress update.

Reply to
Conor

Mondeo not even dropping down and changing around 3500 RPM.

Capri ragging up to 6000RPM when the cam starts to drop off.

Gear ratios are taller in the Mondeo. Mondeo has a taller diff ratio.

Mondeo has a far larger frontal area. Capri is around a foot narrower and over a foot lower. Not sure what the top speed of the Capri is as the speedo stops long before it runs out of acceleration.

Actually, its lower.

Reply to
Conor

_______________________________________________________________________

In many of my cars, girls have been pushed back in their seat.......and that was when the engine was turned off.

Bod

Reply to
Bod

The best interpretation I can put on that is that what you call "torque" is not what a physicist calls "torque".

Reply to
Mike Barnes

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.

Reply to
Conor

s

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

Reply to
The Debacler

Unfortunately, it's the 2.8. I don't 'do' diesels.

The Escort is indeed RWD. I'm devoid of anyting FWD at the mo.

Reply to
Pete M

Good man. I'm glad you're not a diesel apologist. They;re somewhat irritating.

Torque is good stuff, it's just unfortunate that diesel-sniffers think it's a good enough excuse to drive one of their rattling abominations.

I drove my old Volvo T5 back to back with a Mercedes E280CDi not long ago. Volvo has 225 bhp and around 220 lb ft (from 2000-5200 rpm), Merc has around 200 bhp and 336 lb ft (from 1400-2800 rpm). Now, on paper they're pretty evenly matched. Both do 0-60 in 7 something (both Autos), both do close to 150 mph, the Merc is slightly heavier and has the 7G autobox.

The Mercedes has to keep changing gear to try and hide the narrow power band. Where the Volvo can just loaf along in top the Merc is up and down through the box trying to keep the turbo spinning and the illusion of being as good as a petrol. It's a trick the Merc pulls off quite well, Tim K. in here has a similar Merc that it wasn't that easy for the Volvo to keep up with, but it's not the same as being in something with a proper petrol engine.

Try something with a 440 Mopar lump if you want "back in the seat" torque. Seamless, always available, any revs, no delay. Just proper 'oomph' that turbodiesels and little petrol turbos can't imitate..

Reply to
Pete M

Noticably so. I think its more to do with the fact the car is turbocharged and overboosts briefly plus the peak is lower down.

The Capri is more of a constant feeling acceleration whereas the Mondeo is an initial "wahey, we're off".

Reply to
Conor

The Capri 2l doesn't have 130bhp.

Reply to
Nick Finnigan

I was thinking that. I doubt even the 3L has that, even when it was new.

Reply to
Silk

SNIP lots of calcs

This NG is really funny.

One slight post to show that in most situations, torque is more important than power to actual acceleration and I get an insult while we all get a basic Physics lecture :-)

I did do A level Physics, got an A grade, and understand perfectly well that gear ratios and wheel sizes are also important to figure actual forces but.....

Who cares? 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.

Calculating the actual acceleration to 16 decimal places seems rather anal when you look at the title of the original post.

& then you go on to mention drag while pointing out that it's largely irrelevant for the speeds we are talking about! Why bloody mention it then?! & you forgot to mention the coefficient of friction between the road and the tyres. And the tyre pressures. and the tyre widths.........
Reply to
Mark

130 from the 3l, a bit more from the 2.8i.
Reply to
Nick Finnigan

Correct. However one with a Kent FR31 camshaft, 4-2-1 exhaust manifold, K&N air filter and a rejetted carb does.

Reply to
Conor

I doubt it. Unless you could put a turbo on it, none of the above chav tat is going to help.

Reply to
Silk

Conor gurgled happily, sounding much like they were saying:

Would that be a real figure from a dyno? Or a calculation from the packets?

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?

Reply to
Adrian

"The Debacler" wrote

How long is a piece of string?

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 full braking.

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.

Reply to
DavidR

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