Car Talk - Non S2000 General Motoring and Non S2000 Car Talk

Power vs Torque

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Old Jan 14, 2008 | 01:00 PM
  #11  
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[QUOTE=Bada Bing!,Jan 14 2008, 09:51 AM]Spot on.
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Old Jan 14, 2008 | 01:30 PM
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Originally Posted by smnasn,Jan 14 2008, 09:58 PM
It's a fantastic bike, has totally rekindled my love of motorcycling.

The ownership experience is great too.

The motor is interesting, as in Daytona guise it's pushing the technology limits to the max (i.e same power/revs as Jap 4 cylinder engines in a 3 cylinder engine = ballistic cylinder speeds).

Build quality is up there too.

In short, I love it.

Nice one

I seen a green 'Tiger' at the petrol station the other day looked a mean thing, i just didnt like the colour!.

To be honest im not a motorbike fan, but i guess the high revving nature of the S attracts motorcyclists.
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Old Jan 14, 2008 | 01:48 PM
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Originally Posted by smnasn,Jan 14 2008, 09:58 PM
It's a fantastic bike, has totally rekindled my love of motorcycling.

The ownership experience is great too.

The motor is interesting, as in Daytona guise it's pushing the technology limits to the max (i.e same power/revs as Jap 4 cylinder engines in a 3 cylinder engine = ballistic cylinder speeds).

Build quality is up there too.

In short, I love it.

Watch out for the warranty though.

I read something the other day - letter in Perf Bikes I think - where unless you oil, polish, wipe, swab and cuddle it after every ride the warranty is invalidated.

Small print in the manual IIRC
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Old Jan 14, 2008 | 02:04 PM
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I'll take an R8 Diesel, but I'll take a petrol first
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Old Jan 14, 2008 | 02:32 PM
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Originally Posted by gtman,Jan 14 2008, 10:00 PM
Although the diesel will have the initial advantage in acceleration the advantage of the petrol is you can keep it in 4th for much longer therefore quickly negating the initial advantage.

I'm not a great fan of diesel but I will admit that big engined diesels do offer good performance but then again I wouldn't expect an engine with two turbos and 270bhp to be a slouch It's the TDI brigade that I can't stand.

The other thing to note is that whenever these comparisons appear they always compare NA with turbo diesel engines. Without having any stats I would think that the times would be more equal if it was diesel versus turbo petrol engine.

One thing that really puzzles me is the 0-100 mph times of the majority of diesels. Many of the newer diesels will get to 60 in around 7 - 9 secs but then the remaining 40 mph to 100 isn't as comparatively quick. Why?
Why would you be able to keep the petrol in gear longer than the diesel? The petrol has more revs to play with but surely shorter gearing. They both go through their rev range from min to max in the same time.

The 335i is a twin turbo model, and the fastest of the lot.

This was my comparison rather than something BMW have done.

I'll add the power to weight ratios tomorrow (although the weights are broadly similar - 200kgs min to max) so I don't think it will make much difference.

Here's another good one - VW Golfs - unfortunately I don't have the 50-75 times. I suspect that the 16kg difference in weight is not responsible for the whole 0.3secs difference in 0-62 time. The TSi is supercharged and turbocharged.

VW Golf 3d
1.4 GT TSi 167 bhp, Torque 177lb-ft, Weight 1,429kg, 0-62 7.9s
2.0 GT TDi 167 bhp, Torque 258lb-ft, Weight 1,445kg, 0-62 8.2s
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Old Jan 14, 2008 | 02:41 PM
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Originally Posted by GarethB,Jan 14 2008, 11:48 PM
Watch out for the warranty though.

I read something the other day - letter in Perf Bikes I think - where unless you oil, polish, wipe, swab and cuddle it after every ride the warranty is invalidated.

Small print in the manual IIRC
There is something like that for cosmetic claims yes.

And there have been some stories of paint dulling on the black models.

But it usually manifests itself in the first 1000 miles or so.

I've done 2500 miles on my black bike and all ok,looks good as new. I've washed it once...

I can't say it worries me in the least...

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Old Jan 14, 2008 | 02:49 PM
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Originally Posted by lovegroova,Jan 15 2008, 12:32 AM
Here's another good one - VW Golfs - unfortunately I don't have the 50-75 times. I suspect that the 16kg difference in weight is not responsible for the whole 0.3secs difference in 0-62 time. The TSi is supercharged and turbocharged.

VW Golf 3d
1.4 GT TSi 167 bhp, Torque 177lb-ft, Weight 1,429kg, 0-62 7.9s
2.0 GT TDi 167 bhp, Torque 258lb-ft, Weight 1,445kg, 0-62 8.2s
But surely the intersting thing about those is that the 0-60 and power are (almost) the same, but the torque figures are wildly different?

I would imagine the 0.3 sec difference is accounted for by the fact that the diesel will probably require 3rd gear whilst the petrol won't.
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Old Jan 14, 2008 | 03:55 PM
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Originally Posted by lovegroova,Jan 14 2008, 03:32 PM
Why would you be able to keep the petrol in gear longer than the diesel? The petrol has more revs to play with but surely shorter gearing. They both go through their rev range from min to max in the same time.
My point was that the petrol car would have more revs to play with and would not need to change gear as soon as the diesel car.

It would be interesting to know whether both engines get through their revs in the same time, surely there would be a difference. If a diesel with a 4200rpm redline took off at the same time as an S2000 with 9000rpm both drivers wouldn't change gear at the exact same time would they?
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Old Jan 14, 2008 | 10:34 PM
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Plus, if they are changing gear at the same time, but at lower revs, this means a higher final gear, so less 'torque at the wheels' (I know this isn't correct terminology, but you know what I mean).

In the TDCI Mundanos I've driven, it's nice and torquey, but when accelerating, you need to change gear every other second, and wait for the turbo to spool up again. That's why the 'peak' figures aren't a guide to 0-60 time. I guess if you plotted torque or power against the 10s 0-60, you'd get broadly the same area under the curve, but a lot different shape to it.
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Old Jan 14, 2008 | 11:27 PM
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Originally Posted by gtman,Jan 14 2008, 11:00 PM
One thing that really puzzles me is the 0-100 mph times of the majority of diesels. Many of the newer diesels will get to 60 in around 7 - 9 secs but then the remaining 40 mph to 100 isn't as comparatively quick. Why?
Our 335d gets to 100 in <14secs (13.8 IIRC).

The 335i in 12.9 secs, but it has 20bhp more and is 40kg lighter.

I meant to add that I am not convinced the prospect of a diesel over a petrol engine in a sports car is a good idea.... but a good diesel in a GT or cruising car is ideal.

I wouldn't ever put the 335i or 335d in the 'sports car' category, but they are excellent for what they were built for.

I used to be a diesel hater until we testdrove and bought the 335d. That's not to say I am a complete convert as I still prefer to drive sportscars, but I do think the 335d has the first diesel engine that has 'wow' factor.
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