Perfect analogy. That's exactly correct, well if you say power is how hard and how fast. As it's both.
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Someone explain power and tourqe
- Thread starter JaysonD
- Start date
Perfect analogy. That's exactly correct, well if you say power is how hard and how fast. As it's both.
NA is more cultured.
I loved racing a turbo car, rolling starts were so easy to make places up lights out and booooooooost. I'm an NA boy though through and through, I think its because of the simplicity and character over what can often feel benign and fake. It's horses for courses.
We all know engines don't win races, chassis's do.
Chassis / engine / driver
start with any setup of the three and improving any one of them can win a race against the old setup.
I do agree on there is something about a high rpm screamer though being fun and feeling more as one with it etc.
an engine’s output is rated in horsepower and torque. Torque is pulling power, and it’s best demonstrated as the grunt that gets you moving, while horsepower is what keeps you going. Without sounding like your physics teacher, torque is the twisting force created in an engine by rotating parts; horsepower is the measurement of how fast torque is being used. Horsepower and torque work hand-in-hand, as horsepower is calculated from torque.
For the average buyer, torque shouldn’t be a deciding factor unless you know you’ll be towing or hauling heavy loads. And that’s where high-torque vehicles will thrive, driving while towing a trailer . It will be easier to accelerate and sustain speed with a high-torque car in any situation, but especially with heavy loads.
High-performance cars can also produce lots of torque that greatly aid in acceleration. That feeling of your eyeballs being sucked into the back of your head in a fast car during heavy right-foot pounding is an example of excessive torque.
For the average buyer, torque shouldn’t be a deciding factor unless you know you’ll be towing or hauling heavy loads. And that’s where high-torque vehicles will thrive, driving while towing a trailer . It will be easier to accelerate and sustain speed with a high-torque car in any situation, but especially with heavy loads.
High-performance cars can also produce lots of torque that greatly aid in acceleration. That feeling of your eyeballs being sucked into the back of your head in a fast car during heavy right-foot pounding is an example of excessive torque.
Golf GT & A4 Avant
Interesting topic, the cycling analogy is quite a good way of understanding the basics.
I've had a mix of cars from high revving N/A to low revving torquey forced induction both petrol and diesel. Each one has had its own plus points and benefits in different scenarios and diferent driving styles.
What a would say though is when an engine is tuned and the emphasis is on Torque rather than both, it makes for a very boring drive, ie I just can't get excited over driving a performance diesel regardless of how quick they are
I've had a mix of cars from high revving N/A to low revving torquey forced induction both petrol and diesel. Each one has had its own plus points and benefits in different scenarios and diferent driving styles.
What a would say though is when an engine is tuned and the emphasis is on Torque rather than both, it makes for a very boring drive, ie I just can't get excited over driving a performance diesel regardless of how quick they are
The most basic way I can think of explaining it is power is the amount of work the engine completes in a given time frame. Torque is the rotational turning force at the crank.
Generally, more torque = more power. However, you can generate more power from the same amount of torque by spinning the engine faster; probably the best example of this in a street car is a Honda Vtec engine, as they make power as a function of engine speed rather than torque.
Generally, more torque = more power. However, you can generate more power from the same amount of torque by spinning the engine faster; probably the best example of this in a street car is a Honda Vtec engine, as they make power as a function of engine speed rather than torque.
Daniel
ClioSport Moderator
Whichever has fuel
That is absolutely amazing. Genuinely.
Since the age of 16 (When I started at Rolls Royce) everybody I spoke to has tried to explain torque and power to me. At one stage, I had 2 instructors at college and about 3 classmates all with drawings and diagrams etc etc and I still couldn't grasp it. Up until 30 seconds ago I still couldn't get my head round it!
Thank you. I mean that!!
BoatNonce
ClioSport Club Member
I deliberately left gearing out of it, it's a simplified explanation!
182cup & 172 racecar
Like this.
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A Clio 172 and a Civic type are a good example of what's important and how power/torque affects a car.
Clio 165-170 bhp circa 150lbft, Civic 200bhp circa 145bhp
In a lap of a track they're almost identical in standard form (if its not too twisty) although the Clio gives away power to the Civic and the Civic almost matches the Clio in torque. The Civic only makes its numbers high up the revs where as the Clio's is wider spread.
It just shows that in real life situation that power is nothing without torque and vice versa.
Clio 165-170 bhp circa 150lbft, Civic 200bhp circa 145bhp
In a lap of a track they're almost identical in standard form (if its not too twisty
) although the Clio gives away power to the Civic and the Civic almost matches the Clio in torque. The Civic only makes its numbers high up the revs where as the Clio's is wider spread.It just shows that in real life situation that power is nothing without torque and vice versa.
Knuckles
ClioSport Admin
A Clio 172 and a Civic type are a good example of what's important and how power/torque affects a car.
Clio 165-170 bhp circa 150lbft, Civic 200bhp circa 145bhp
In a lap of a track they're almost identical in standard form (if its not too twisty
It just shows that in real life situation that power is nothing without torque and vice versa.
Civic is around 20 percent more power and around 20 percent more weight.
So it's power to weight ratio is approx the same, but it's torque to weight ratio is much lower than the Clio.
So I would say it shows the opposite of what you are claiming. Ie that it's the power to weight ratio being so similar that gives them similar performance despite there being a big difference in torque to weight ratio which has no effect as the civic you are geared lower at any point in time thus recovering the torque deficit via mechanical advantage.
as I've said before f=ma
it really is pretty much that simple. So more weight slows you down and more power speeds you up. Torque at flywheel is largely irrelevant, it's torque at wheels that matters and that is governed only by power and gearing.
also go and look at some Rolling road graphs and you will see the civic makes within 10 percent of peak torque from 2500 to over 8k rpm, so contrary to what you are saying has a wider spread of torque than the Clio does (surprising if you have driven one and just goes to show it's power that's more important than people realise)
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I know what I'm trying to say, even lightly tuned Civic's so circa 220bhp & 160lbft are nothing special other than above 120mph.
Fair enough the civic weighs a little bit more than a Clio. Contrary to what you have said they are pithless on anything other than flat road despite how they feel when in or driving one, noise goes a long way to make you 'think' your going fast.
I have raced enough of them up hills even my mates DC5's but that's not what this thread is about.
Fair enough the civic weighs a little bit more than a Clio. Contrary to what you have said they are pithless on anything other than flat road despite how they feel when in or driving one, noise goes a long way to make you 'think' your going fast.
I have raced enough of them up hills even my mates DC5's but that's not what this thread is about.
Seriously everytime I sort of get my barings with this, someone turns my head back to gravy! I'm very slowly getting there
That has hit the nail on the head for me, coming from a biking background, so thank you!
A 220bhp civic is only same power to weight ratio as about a 185bhp Clio. And you wouldn't expect a big difference between a typical Clio and a 185bhp one. The numbers are just too close.
Power is the key thing for acceleration despite common misconceptions. But there is the proviso that it needs to be geared appropriately.
182
To those still musing over this, wanting a laymans explanation...
Firstly, dismiss the idea that torque is accelleration and power is top speed. It doesn't explain anything properly because an engine doesn't drive the wheels directly. The force an engine produces (torque) is converted by the gearbox to give a different force at the wheels, which is what is needed both to make a car accellerate and go fast. The longer the gearing the lower the force at the wheels, so in top gear you have less accelleration than in first, and also why you can't just make a car with ever higher gears to make it go faster (the force will be reduced too much to be effective and it would loose speed).
To quote from above -
"torque is how hard you pedal your bikes pedals, power is how fast you spin them"
I like that analogy, but as Chip has said already, it is not quite complete to be accurate enough - power is how fast AND how hard. You can measure the fast and the hard, and you need both to calculate power, as it can't be measured directly.
But... you generally can't go hard AND fast (ahem, steady!) so you tend to have a trade-off with a car engine, meaning that as revs rise beyond a critical point, so torque is reduced. Both are needed, but the amounts of either "fast" (RPM) or hard (torque) can be heavilly biased toward one or the other and still give the same BHP result. They are the two sides of the power equation... power = torque x RPM. Its as simple as that.
Once you've got your head around the idea that power (BHP) is not a force you can feel directly, it will all click into place. Appart from it being explained in physics equations, the reason why it is important to car performance (both accel and top speed) is because it is the best way of representing the optimum amounts of torque and RPM for an engine to give its maximum performance. The engine RPM at which you will find the most amount of force at the wheels for any given road-speed (i.e if you could choose any gear) is the peak power RPM. And the higher the BHP figure the more performance, so long as you are able to gear the car to use that particular engine speed.
Firstly, dismiss the idea that torque is accelleration and power is top speed. It doesn't explain anything properly because an engine doesn't drive the wheels directly. The force an engine produces (torque) is converted by the gearbox to give a different force at the wheels, which is what is needed both to make a car accellerate and go fast. The longer the gearing the lower the force at the wheels, so in top gear you have less accelleration than in first, and also why you can't just make a car with ever higher gears to make it go faster (the force will be reduced too much to be effective and it would loose speed).
To quote from above -
"torque is how hard you pedal your bikes pedals, power is how fast you spin them"
I like that analogy, but as Chip has said already, it is not quite complete to be accurate enough - power is how fast AND how hard. You can measure the fast and the hard, and you need both to calculate power, as it can't be measured directly.
But... you generally can't go hard AND fast (ahem, steady!) so you tend to have a trade-off with a car engine, meaning that as revs rise beyond a critical point, so torque is reduced. Both are needed, but the amounts of either "fast" (RPM) or hard (torque) can be heavilly biased toward one or the other and still give the same BHP result. They are the two sides of the power equation... power = torque x RPM. Its as simple as that.
Once you've got your head around the idea that power (BHP) is not a force you can feel directly, it will all click into place. Appart from it being explained in physics equations, the reason why it is important to car performance (both accel and top speed) is because it is the best way of representing the optimum amounts of torque and RPM for an engine to give its maximum performance. The engine RPM at which you will find the most amount of force at the wheels for any given road-speed (i.e if you could choose any gear) is the peak power RPM. And the higher the BHP figure the more performance, so long as you are able to gear the car to use that particular engine speed.
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No because the rolling road measures the speed of the rollers and the amount of torque turning the rollers and the engine speed as well (either directly from an ignition lead/injector or via a sync) and then it calculates accordingly from there.
If you get the sync speed wrong the bhp will still read correctly but the engine torque and rpm will read wrongly.
So in an extreme example if the sync was reading double engine revs then it would plot you power curve as twice as high rpm and half torque.
So if at 4000 you had 150lbft it would instead think at 8000 you had 75lbft.
And that translates in both cases to a bhp of 114bhp
so all the bhp figures would still work but placed at the wrong rpm.
What was that a reply to mate? Not sure what context to read it in.
BHP is derived from torque, a car with low down torque and a car with high torque with exactly the same BHP will win in different situations. The car low torque will pull away first, but the car with high torque, will catch up. At least, that's what I think it is? Don't take my word for it, I'm usually wrong.
BHP = How fast you can go.
Torque = How fast you get there.
Bhp is how fast you can go and how fast you can get there really.
I guess you could say as a rough approximation:
bhp = top speed
bhp = acceleration when revving car hard
torque = in gear acceleration where you just put your foot down but don't drop down a couple of gears to allow you to rev the engine
I think that's just about done it for me! Cheers pal!
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