Is torque really relevant?
Discussion
otolith said:
MC Bodge said:
otolith said:
The point is that whether or not that one particular gear and speed happens to be a good one for a given engine and gearbox doesn't tell you whether it's a good car or not. It's a crap metric. It's barely relevant when comparing very similar cars with very similar powertrains, and complete b
ks when comparing a turbodiesel and a turbo petrol and a high revving NA petrol.
On the contrary, if it is a daily scenario, it is a useful indication.ks when comparing a turbodiesel and a turbo petrol and a high revving NA petrol. 
I always get caught out driving the company Octavia's until I adjust as they perform fine but be in anything like the wrong gear, even slightly and you end up stranded.
Wont be a problem with EV's I guess, thats the weird thing about Teslas, went in one and its not so much the level of acceleration as the immediacy and lack of punctuation by gearchanges. Whers my Mercedes, when you hoofed it would have a chat with the gearbox, arrange a meeting for the following day to discuss what gear to go into, engine would start bellowing and off we went, not as quickly as a Tesla but still quite quickly, it was the complete lack of even momentary preamble that stunned me.
rockin said:
ddom said:
Gary C said:
Merc 500SL lost power in the 90's when it lost its overfuel facility. Rather than ensuring complete burn, it needed to overfuel and run a bit rich to get the best BMEP, which resulted in some fuel not being burnt. So yes, peak power can be delivered 'rich'
I've never seen an engine make more power than when it was slightly lean. Obviously these chancers who tried to flog all manner of kit with headline numbers were all trying it on, but you couldn't compete in them otherwise they would go pop."5.0
The 5.0 L (4,973 cc) version produced 326 PS (240 kW; 322 bhp) at 5700 rpm and 480 N⋅m (354 lb⋅ft) of torque at 3900 rpm. Later engines had the full throttle enrichment removed and power was a little less, closer to 320 PS (235 kW; 316 bhp)."
otolith said:
MC Bodge said:
otolith said:
The point is that whether or not that one particular gear and speed happens to be a good one for a given engine and gearbox doesn't tell you whether it's a good car or not. It's a crap metric. It's barely relevant when comparing very similar cars with very similar powertrains, and complete bks when comparing a turbodiesel and a turbo petrol and a high revving NA petrol.
On the contrary, if it is a daily scenario, it is a useful indication.ks when comparing a turbodiesel and a turbo petrol and a high revving NA petrol. But feel free to keep the debate about labouring engines.
Equus said:
Gary C said:
The only torque that counts is the torque applied at the wheel hub, all the rest is about getting it there.
Even that's not the end of the story: you might as well say that its the (linear) thrust and velocity at the tyre contact patch that is of ultimate importance, because of course the rolling diameter of the tyre is just another step in the gearing.But there are many ways of getting there, and different genres of engine (including diesel, which is what this thread is about) have characteristic... erm... characteristics that mean it's possible to generalise to some degree.
Generally, a high torque engine with a flat torque curve is produced by high capacity and is generally easy to drive, never leaves you really in the 'wrong' gear, a 'low' torque engine with similar power is by maths, going to deliver at higher revs and in the past that would normally mean using all sorts of induction tricks to fill the cylinders at high revs that results in narrow torque curves and requires more 'effort'
Throw in a turbo and the torque curve can be almost anything you want.
There is really no need to have a high rev peaky IC engine these days, but I miss them.
Equus said:
Mave said:
Ah the old power versus torque nonsense argument. Power is usually calculated from torque. Attempting to differentiate between them is just silly.
Power is calculated from torque and revs.Neither peak power nor peak torque will tell the whole story - even when you take gearing into account, it's the area under the curve that makes a difference - but as a broad but usually accurate generalisation, a 'torquey' engine will be more flexible and offer better acceleration (even after allowing for gearing) than a 'peaky' one.
Or perhaps you're trying to tell us that attempting to differentiate between an engine (say a 5-litre TVR Rover V8) that produces a peak power output of 270bhp and peak torque of 300 lb.ft and another (say a tuned N/A 2 litre Duratec) that produces an identical 270bhp but a peak torque of 190lb.ft is just silly, because they will drive just the same?
anonymous said:
[redacted]
Damn right.I'm having to tool round in a Citroen C3 courtesy car at the moment, 'cos my usual transport got caught in the garage by Covid.
f
king hateful little thing it is - 1.0 litre triple that you've got to thrash the nuts off and stir the gears on constantly to maintain any semblance of reasonable progress. Bouncing off the rev limiter in stuff like a K-series Elise or Locaterfield is great fun in small doses, but when you need to do Norfolk to Exeter and back again in a day on a regular basis, it's absolute purgatory. Give me a nice, torquey diesel and a ZF 8-speed autobox, any day of the week.
RobM77 said:
What is it about the real world that prevents you from changing into an appropriate gear for a given situation?
The same thing that prevents you from driving a car with a cranking handle instead of an electric starter, no heater (never mind aircon) and a little advance-retard lever on the steering wheel....In other words, nothing at all, but most people demand a greater degree of flexibility and convenience from their transport these days.
anonymous said:
[redacted]
Correct me if I'm wrong, but I thought what was being discussed was comparing engines based on how well they accelerate in the wrong gear? I was merely commenting that was a very odd way to compare engines.With regard to heel and toe, many people, me included, always change gear using rev-matching. It's only heel and toe if you're braking at the same time, but yes, if I'm braking I always heel and toe, even if slowing in a traffic jam. I learnt to do it when I learnt to drive aged 17 and I've done it ever since, to the point where it doesn't require thought any more. It would genuinely take me more effort and thought to change gear without rev-matching than with rev-matching.
RobM77 said:
Correct me if I'm wrong, but I thought what was being discussed was comparing engines based on how well they accelerate in the wrong gear? I was merely commenting that was a very odd way to compare engines.
With regard to heel and toe, many people, me included, always change gear using rev-matching. It's only heel and toe if you're braking at the same time, but yes, if I'm braking I always heel and toe, even if slowing in a traffic jam. I learnt to do it when I learnt to drive aged 17 and I've done it ever since, to the point where it doesn't require thought any more. It would genuinely take me more effort and thought to change gear without rev-matching than with rev-matching.
No, no, no. With regard to heel and toe, many people, me included, always change gear using rev-matching. It's only heel and toe if you're braking at the same time, but yes, if I'm braking I always heel and toe, even if slowing in a traffic jam. I learnt to do it when I learnt to drive aged 17 and I've done it ever since, to the point where it doesn't require thought any more. It would genuinely take me more effort and thought to change gear without rev-matching than with rev-matching.
The thread took an odd turn. What was being discussed was being able to cruise along in top gear and having to change down a couple of gears, or not, to allow reasonable, not maximum, acceleration on the road. Somebody brought up a daft scenario and continued to milk it.
Let's not get into heel & toe etc.
There is a way that some people drive, which requires lots of acceleration in the wrong gear. Not needing to change down is maybe nice to have (and automatic is even nicer for that kind of chore driving, which is what I use my 3 litre automatic diesel for) - if your driving style is such that not having time to change gear between deciding to accelerate and accelerating is often a problem, that's a different matter, and the situation for which I would suggest addressing your driving style to give yourself more time rather than buying something that lets you lunge more easily without thinking.
otolith said:
There is a way that some people drive, which requires lots of acceleration in the wrong gear. Not needing to change down is maybe nice to have (and automatic is even nicer for that kind of chore driving, which is what I use my 3 litre automatic diesel for) - if your driving style is such that not having time to change gear between deciding to accelerate and accelerating is often a problem, that's a different matter, and the situation for which I would suggest addressing your driving style to give yourself more time rather than buying something that lets you lunge more easily without thinking.
Some people do go on a bit, don't they? MC Bodge said:
Driving along in top at 60mph. Some cars accelerate nicely. Others need down-shifts. The former is generally preferable for normal road driving.
Labouring your engine in top gear in a typical 5/6 gear car at 30mph is just a contrived scenario.
Not at all, I had an EP3 Civic previously and it's very low gearing coupled with a 2L engine and relatively low weight meant it would easily pull 30mph in 6th without labouring it in the slightest. You would need to drop a couple of gears if you wanted strong acceleration from that point, but pushing a clutch and a operating a gear lever is honestly not difficult.Labouring your engine in top gear in a typical 5/6 gear car at 30mph is just a contrived scenario.
otolith said:
There is a way that some people drive, which requires lots of acceleration in the wrong gear.
I'm sure it's merely coincidental that certain drivers tended to suffer premature DMF failures in diesels Edited by LimSlip on Tuesday 7th July 17:50
I've come from a string of cars that were fairly small capacity, naturally aspirated engines with quite low torque to my current Cooper S, which lets you get away with far more liberties in terms of what gear you're in. Clearly I am no stranger to having to actually *drive* my cars, but I won't lie, having decent torque in any gear IS nice. Relevant? Absolutely. Not sure I would actually want to go back to those thrashy small engines again now, not for road use anyway.
Agreed with the poster above about Hondas, all of mine were perfectly drivable in high gears at low speeds. Not much torque, certainly, but they were sure tractable.
Agreed with the poster above about Hondas, all of mine were perfectly drivable in high gears at low speeds. Not much torque, certainly, but they were sure tractable.
The problem is with all this “get in the right gear” view is less and less relevant on the public UK roads.
As any petrol head knows LEGAL speed limits you can only get MAX power in 1st and second gear whereas 3rd is in the 80-120mph range depending on how much grunt your car has as such changing down a few gears isn’t really that doable - unless of course do many here nip into 1st for the maximum attack out of a corner.
As any petrol head knows LEGAL speed limits you can only get MAX power in 1st and second gear whereas 3rd is in the 80-120mph range depending on how much grunt your car has as such changing down a few gears isn’t really that doable - unless of course do many here nip into 1st for the maximum attack out of a corner.
TameRacingDriver said:
I've come from a string of cars that were fairly small capacity, naturally aspirated engines with quite low torque to my current Cooper S, which lets you get away with far more liberties in terms of what gear you're in. Clearly I am no stranger to having to actually *drive* my cars, but I won't lie, having decent torque in any gear IS nice. Relevant? Absolutely. Not sure I would actually want to go back to those thrashy small engines again now, not for road use anyway.
Agreed with the poster above about Hondas, all of mine were perfectly drivable in high gears at low speeds. Not much torque, certainly, but they were sure tractable.
Exactly. I can't think of anything worse when you are not in the mood. With a larger cpacity torquey engine it's more fun, most of the time. Take the S2000 vs Boxster. It's far more pleasant to pedal the Porker down unfamiliar roads.Agreed with the poster above about Hondas, all of mine were perfectly drivable in high gears at low speeds. Not much torque, certainly, but they were sure tractable.
ddom said:
Exactly. I can't think of anything worse when you are not in the mood. With a larger cpacity torquey engine it's more fun, most of the time. Take the S2000 vs Boxster. It's far more pleasant to pedal the Porker down unfamiliar roads.
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