Horsepower or Torque?

Jesus. · 28-11-2013 01:12AM #1

Which is the real rating you should be looking at in order to evaluate a car's potential performance?

I've come to the conclusion that Torque is where its at. At least for real World driving anyway.

What do you think guys? Which do you think is the best guide as to how nippy a Motor might be?

TheBully · 28-11-2013 01:29AM

Its all about girth in my opinion

conzy · 28-11-2013 01:34AM

How fast a car can accelerate and its top speed is all about horsepower.

Torque is what rotates the wheels, an engine with more horsepower applies more torque to the wheels through the gearbox.

The engines peak torque figure is pretty irrelevant but a car where it arrives low in the Rev band or is near peak torque for a lot of the Rev band will feel more "driveable"

Celly Smunt · 28-11-2013 01:36AM

I guess it all comes down to how much you like wheel spinning

ItsLikeThis · 28-11-2013 01:36AM

Jesus. wrote: »

Which is the real rating you should be looking at in order to evaluate a car's potential performance?

I've come to the conclusion that Torque is where its at. At least for real World driving anyway.

What do you think guys? Which do you think is the best guide as to how nippy a Motor might be?

Its all about how much "poke" you have

Cogsy88 · 28-11-2013 01:38AM

More horsepower increases top speed.
More torque increases acceleration.

pajor · 28-11-2013 01:40AM

Well as I read before:

Horsepower is the measure of how fast you'll crash into the wall.

Torque is the measure of how much of the wall you'll take with you.

Jesus. · 28-11-2013 02:07AM

I was reading these Yanky Boy's comments earlier and they all seem to think Torque is the key measurement:

http://answers.yahoo.com/question/index?qid=20081214200954AA2VAsm

Conzy, the way I see it this: You could have a decent amount of horsepower and indeed she might go fairly quick but you'd have to cane the sh*t out of her. In other words, it feels like you're doing an awful lot of work to get the car up to speed. On the other hand, if you had a decent amount of torque (Diesel?), it mightn't be any quicker but it seems to do the acceleration without much effort and feels a lot "easier".

That's the best way I can describe what I've found to be the difference between a "torquey" turbo-diesel and a petrol with the same bhp but less torque. Do you know what I mean?

CianRyan · 28-11-2013 02:29AM

The most obvious answer seems to me to be, one is useless without the other.
Unless you're running a really light car, HP will feel weak without torque in a heavy car, torque may feel quick as it pushes you back but without the HP, if you look at the needle you'll realise the speed isn't going up all the quickly.

So in a performance car, I like somewhat equal measures of both.

CiniO · 28-11-2013 02:35AM

Jesus. wrote: »

Which is the real rating you should be looking at in order to evaluate a car's potential performance?

I've come to the conclusion that Torque is where its at. At least for real World driving anyway.

What do you think guys? Which do you think is the best guide as to how nippy a Motor might be?

I think the best measure of car performance is 0-62mph acceleration value.
Maximum power or maximum torque on it's own doesn't tell us much, without knowing car weight, revolutions at which they appear, gearing, wheel size and plenty of calculations.

CianRyan · 28-11-2013 02:37AM

CiniO wrote: »

I think the best measure of car performance is 0-62mph acceleration value.
Maximum power or maximum torque on it's own doesn't tell us much, without knowing car weight, revolutions at which they appear, gearing, wheel size and plenty of calculations.

I'd argue a standing 1/4 or 1/2 mile if you want it from 0, in the real world it's going to be 50-100 and the likes.

CiniO · 28-11-2013 02:43AM

CianRyan wrote: »

I'd argue a standing 1/4 or 1/2 mile if you want it from 0, in the real world it's going to be 50-100 and the likes.

Most cars have 0-62mpg (0-100km/h) specified by manufacturer.

If I see two cars. Car A does 0-100km/h in 8s, car B in 10s, then I know which one is faster. It nearly as simple as that.

dgt · 28-11-2013 02:46AM

Its not just about torque and hp but how they're used. A high revving engine might produce some serious hp but will be fairly high up the rev range and won't be great low down. Well tuned diesels have serious useable power and torque but are usually out of puff around 5k rpm.

A Decent petrol with a usable linear torque curve at lowish rpm and high power in upper ranges is the way to go for a good all rounder

CianRyan · 28-11-2013 02:52AM

CiniO wrote: »

Most cars have 0-62mpg (0-100km/h) specified by manufacturer.

If I see two cars. Car A does 0-100km/h in 8s, car B in 10s, then I know which one is faster. It nearly as simple as that.

They make for great reading and everyone loves a good launch but how often do you pull over at the side of a motor way to do a 0-60 test?
I far more often find myself pulling at speed.

CiniO · 28-11-2013 02:57AM

CianRyan wrote: »

They make for great reading and everyone loves a good launch but how often do you pull over at the side of a motor way to do a 0-60 test?
I far more often find myself pulling at speed.

Yes, but one usually follows the other.

If car A does better 0-100km/h than car B, then in vast majority of cases it will also better accelerate from 80km/h to 160km/h.

Exceptions would be very rare.

CianRyan · 28-11-2013 03:03AM

CiniO wrote: »

Yes, but one usually follows the other.

If car A does better 0-100km/h than car B, then in vast majority of cases it will also better accelerate from 80km/h to 160km/h.

Exceptions would be very rare.

Not totally true but I get where you're coming from.
Take my MX5 for example, it's quite snappy from 0-40mph but when you're at motor way speeds and fancy a lash it won't go half as well as it did low down.

Now take something heavy, (not my area of expertise), it may not be so quick from 0-60 but if it's a got a big turbo on it, it will absolutely fly when it's already moving and under boost.

Matt Simis · 28-11-2013 03:26AM

CiniO wrote: »

Yes, but one usually follows the other.

If car A does better 0-100km/h than car B, then in vast majority of cases it will also better accelerate from 80km/h to 160km/h.

Exceptions would be very rare.

Only when looking at "normal cars" and relatively uninteresting 0-100kph figures like +8sec. Apply that logic to across the board to cars with sub-6sec 0-60 and it fails big time as weight and traction have much larger impacts and in different areas while the sub-6 speed itself is a difficult target to reach but can be done via lightweight (and likely small engine) or lots of power (and likely heavier car).

corkgsxr · 28-11-2013 09:25AM

If you follow that you'd buy a tractor and wonder why its not a ferrari.

You need to drive them. Unless you can see a dyno to see where it makes power and torque your only guessing

keithclancy · 28-11-2013 09:39AM

corkgsxr wrote: »

If you follow that you'd buy a tractor and wonder why its not a ferrari.

You need to drive them. Unless you can see a dyno to see where it makes power and torque your only guessing

Indeed .... Drive them ... The numbers don't mean anything until you take around a few bendy bits of road.

Anan1 · 28-11-2013 09:47AM

Jesus. wrote: »

Which is the real rating you should be looking at in order to evaluate a car's potential performance?

I've come to the conclusion that Torque is where its at. At least for real World driving anyway.

What do you think guys? Which do you think is the best guide as to how nippy a Motor might be?

At the end of the day, it's all about horsepower. If you have that then torque is only a gearchange away. Think about how horsepower is calculated.

jimgoose · 28-11-2013 09:49AM

I like to look at power and torque curves, as printed by a dyno, where possible. That gives a much more complete story.

Cienciano · 28-11-2013 09:50AM

Cogsy88 wrote: »

More horsepower increases top speed.
More torque increases acceleration.

No, definitely not because:

corkgsxr wrote: »

If you follow that you'd buy a tractor and wonder why its not a ferrari.

You need to drive them. Unless you can see a dyno to see where it makes power and torque your only guessing

Plenty of tractors have the same HP as a cheap underpowered hatchback
Gearbox ratio is another factor.

BTW, I'll admit, no matter how many times it's explained to me, I don't understand what torque is.

jimgoose · 28-11-2013 09:56AM

Cienciano wrote: »

...BTW, I'll admit, no matter how many times it's explained to me, I don't understand what torque is.

You have a piston connected to a main-shaft via a crank offset. Consider a torque wrench. The bolt is the mainshaft, the wrench is the crank offset, and your hand is the piston. The better the explosions that happen above the piston, the more torque. The larger the crank offset, the more torque. RPM is about how often that happens, i.e. how quickly the torque is produced, i.e. power. An engine that produces lots of torque lower-down in the revs will feel very driveable and "nippy" for the kind of driving most people do, but will tend to run out of puff with high revs and the limits of that engine's volumetric efficiency approaches, due to head/port/piston design, valvegear and what-have-you. A high-bhp screamer by contrast will go like sh!it-off-a-stick but will need more caning, i.e. revs.

This is mainly why most manufacturers are messing about with some variant of variable valve/camshaft timing, by the way.

Kenny Logins · 28-11-2013 10:03AM

Cienciano wrote: »

No, definitely not because:

Plenty of tractors have the same HP as a cheap underpowered hatchback
Gearbox ratio is another factor.

BTW, I'll admit, no matter how many times it's explained to me, I don't understand what torque is.

Think of your arm undoing a tight nut or bolt, or standing on the pedals to cycle uphill.

sebastianlieken · 28-11-2013 10:21AM

Consider some examples at the far end of the spectrum from eachother:

Motorbike: Yamaha YZF-R1

Horsepower: 146 bhp @ 11,500 rpm (109 Kw)
Torque: 98 Nm
Weight: 177 kg

Tractor: John Deere 8335R

Horsepower: 335 bhp @ 1,900 rpm (246 Kw)
Torque: 1569 Nm
Weight: 13003 kg

I'm sold, Gimme that tractor and i'll take on all ye' scally wags!

Ignore the fact that the R1 has 800 bhp per 1000 kg more than the tractor and that it's geared for speed rather than torque. :pac:

corkgsxr · 28-11-2013 10:29AM

sebastianlieken wrote: »

Consider some examples at the far end of the spectrum from eachother:

Motorbike: Yamaha YZF-R1
Horsepower: 146 bhp @ 11,500 rpm (109 Kw)

Torque: 98 Nm

Weight: 177 kg

Tractor: John Deere 8335R
Horsepower: 335 bhp @ 1,900 rpm (246 Kw)

Torque: 1569 Nm

Weight: 13003 kg

I'm sold, Gimme that tractor and i'll take on all ye' scally wags!

Ignore the fact that the R1 has 800 bhp per 1000 kg more than the tractor and that it's geared for speed rather than torque. :pac:

Ah but the tractors a turbo diesel I don't think you considered that.
On the minus its not a vag so wouldn't be as good.

dr.fuzzenstein · 28-11-2013 10:58AM

It's very simple:

https://www.youtube.com/watch?v=fgLNO3ThGD4

sebastianlieken · 28-11-2013 11:05AM

Jesus. wrote: »

Which is the real rating you should be looking at in order to evaluate a car's potential performance?

I've come to the conclusion that Torque is where its at. At least for real World driving anyway.

What do you think guys? Which do you think is the best guide as to how nippy a Motor might be?

To try and answer your question a bit better actually:

Consider a Golf GTI vs a GTD.

GTI 1,984 cc (121 cu in) I4 (CCZA) 150 kW (210 PS) @ 5,300-6,200 280 N·m (207 lb·ft) @ 1,700-5,200 6.9 s 240 km/h (149 mph)
GTD 1,968 cc (120 cu in) I4 (CBBB) 130 kW (170 PS) @ 4,200 350 N·m (258 lb·ft) @ 1,750–2,500 7.8 s 222 km/h (138 mph)

Both have 2 litre engines. One is a petrol, one is a diesel. As you can see - petrol has more horsepower, diesel has more torque. The petrol engine has a better 0-60 time if that's how you like to measure performance.

maybe that helps to draw a comparison of whether you prefer bhp or torque. You kinda have to take one with the other though and look at the whole picture.

jimgoose · 28-11-2013 11:09AM

sebastianlieken wrote: »

To try and answer your question a bit better actually:

Consider a Golf GTI vs a GTD.

GTI 1,984 cc (121 cu in) I4 (CCZA) 150 kW (210 PS) @ 5,300-6,200 280 N·m (207 lb·ft) @ 1,700-5,200 6.9 s 240 km/h (149 mph)
GTD 1,968 cc (120 cu in) I4 (CBBB) 130 kW (170 PS) @ 4,200 350 N·m (258 lb·ft) @ 1,750–2,500 7.8 s 222 km/h (138 mph)

Both have 2 litre engines. One is a petrol, one is a diesel. As you can see - petrol has more horsepower, diesel has more torque. The petrol engine has a better 0-60 time if that's how you like to measure performance.

maybe that helps to draw a comparison of whether you prefer bhp or torque. You kinda have to take one with the other though and look at the whole picture.

There are a couple of interesting things about that: one, the diesel makes it's peak torque at higher revs than the petrol. But look at how long the petrol hangs on to both peak power and torque! :cool:

conzy · 28-11-2013 11:09AM

Everyone is thinking about this too much

Horsepower is a measurement of how quickly the engine can get work done.

Two cars the same weight

One has 100Nm of torque and is 400HP (it probably revs to a silly rpm)

One has 900Nm of torque and is 300HP (very low revs)

Providing both are geared optimally.

The one with 400HP will accelerate faster AND have a higher top speed.

Engine torque is largely irrelevant since the invention of this magical box called a "gearbox" that can take low torque at high rpm and convert it to higher torque at a lower RPM.

jimgoose · 28-11-2013 11:11AM

conzy wrote: »

...Engine torque is largely irrelevant since the invention of this magical box called a "gearbox" that can take low torque at high rpm and convert it to higher torque at a lower RPM.

Ever driven a Dodge Charger? It's actually true - the planet spins backwards briefly!

Horsepower or Torque?

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