Horse Power and Torque
- Thread starter Lextreme II
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The 1UZFE EGR Delete Kit is available for sale here.
You are not getting it.
Review the above, think about it.
The hammer example clearly shows the 10 pound hammer doesn't finish the race at all.
The 8 pound hammer wins with LESS force (torque).
Completely wrong.
OK, I will take the time to explain so please read and do the simple math to understand.
GEARING makes all the difference.
Let's make this easy and say that a TIRE RPM of 800rpm = 60mph
Now, we need to find out what ENGINE rpm is needed to reach any given speed. If we want 30mph that would of course need 400rpm at the wheels.
OK, your 2 examples work out this way.
300tq and 500hp means the engine is turning 8750rpm to make 500hp.
500tq and 300hp means the engine is turning 3150rpm to make 300hp.
Gear each car to be at peak HP at 30mph and you get 21.875 to 1 ratio for the 500hp and 7.87 to 1 ratio for the 300hp.
Now, multiply each engines torque by the gear ratio to find out the torque available at the wheels for each engine.
500hp/300tq: 300 x 21.875 = 6563 lb/tq at the wheels
300hp/500tq: 500 x 7.87 = 3938 lb/tq at the wheels
So, at the wheels, the 500hp engine enjoys 2625 pounds of torque at the wheels MORE than the 300hp engine.
In fact you could gear the 500hp engine to be at peak power at 45mph and it would STILL make 437 more torque at the wheels than the 300hp engine at 30mph!!!
I repeat... POWER is king.
UZZ30-Québec
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340i
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well i didnt intend on my metric/imperial comment hijacking this ressurected thread, but the last few posts are halarious. keeping imperial measurement so that the length of a football field is a nice round number?? lol i wouldnt expect anything more from a country which voted bush as president. this is the sort of logic which leads to the nations auto makers making billions in losses while their japanese (metric, btw) counterparts make billions in profits. i cant be bothered researching this, but am quite sure that across the world (the whole world, not th us world), metric is the more commonly used measurement.
and before anyone points it out, nz doesnt make cars.
i read a similar story a while back about computer 'QWERTY' keyboards, which are not actually the best layout. they're intentionally difficult to type on, which was to slow typists down back when typrewriters werent very good and would jam if you typed fast. too many people learnt to type on these crap layout typewriters and the qwerty layout will never change now due to this fact. much like the change from imperial to metric. it seems you truly cant teach an old dog new tricks.
this will be my last post in this thread, as i feel my opinions my be slightly offensive to those patriotic users of this forum. i think america is great, i just dont like some systems it uses.
and before anyone points it out, nz doesnt make cars.
i read a similar story a while back about computer 'QWERTY' keyboards, which are not actually the best layout. they're intentionally difficult to type on, which was to slow typists down back when typrewriters werent very good and would jam if you typed fast. too many people learnt to type on these crap layout typewriters and the qwerty layout will never change now due to this fact. much like the change from imperial to metric. it seems you truly cant teach an old dog new tricks.
this will be my last post in this thread, as i feel my opinions my be slightly offensive to those patriotic users of this forum. i think america is great, i just dont like some systems it uses.
i dont like bush (nor did i vote for him...) but what did you really expect? a wash-out in gore, or a dude that makes ketchup to win? i mean really lol
AFA imperial VS metric, it's not complicated. It's nothing more than being use to what you grew up with. i grew up with both. neither bothers me, but it'll be a cold day in hell before a football field is meters.
AFA imperial VS metric, it's not complicated. It's nothing more than being use to what you grew up with. i grew up with both. neither bothers me, but it'll be a cold day in hell before a football field is meters.
MightyAl
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I had to chime in on imperial v. metric. This is why I love to work on japanese manufactured cars. One set of tools. I have torn down my share of trans ams and dear god I dont understand how those guys do it. There is a horrendous mix of imperial and metric nuts and bolts. As an engineer I wish we would go metric and get rid of all the goofy conversions we have to do. In college teachers would throw in a test question in imperial units and you knew when everyone got to that question when they groaned.
jibbby
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It's those specialty star nuts with five or six groves that drive me nuts.. I forgot the name of those funky star bolt heads and star nuts needless to say they drive me crazy trying to find the right fit when I probably don't even own the right tool size.... Allen bolt heads I can deal with....
Back to subject torque is king..
Back to subject torque is king..
StacytheBloke
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well i am in england and we are really weird when it comes to units, our speed limits are in mph and distances on road signs are in miles however we are metric and mostly use metric tools.
Oddly english imperial tools are different to american imperial tools (like gallons which are also different), americans use a/f spanners (across flats) we use the whitworth system, hence why you need different spanners to work on a harley and a triumph (unless its a modern triumph in which case it is metric)
However we are all proficient in both systems which means we have some real odd balls like the weather, when it is hot we talk in farenheit, eg 'its hot today, its gotta be nearly 100' buuut when it is cold we use centigrade eg 'its freezing, its minus 10 outside'
You ask an english man how tall he is and he will say 6ft 1", and if you ask him how much he weighs he will say 13 and 1/2 stone (1 stone is 14lbs btw as americans dont use stone much) and he will buy his beer in pints buuut his pepsi comes by the litre.
petrol is priced by the litre, but cars are sold with economy figures in mpg, the list is endless.
I will say one thing though as a scuba diver i love the metric system, 1 litre of water weighs 1 kg so displace a litre and you have a kilo of boyancy, decend 10 meters and the pressure increases by 1 bar, a 10 litre tank of air charged to 300 bar contains 3000 litres of air at atmospheric pressure, atmospheric pressure being about 1 bar or 1 atmosphere which is the weight of a 1cm x 1cm column of air 1 km tall.
Try doing all that in your head in imperial.
On the whole HP vs Torque thing, torque give you acceleration, however you need hp to overcome things like wind resistance at a said speed. The buggatti veyron has 1000hp so it can maintain such a high top speed whilst generating the downforce required to keep it on the road which creates drag. What the engineers would have done is modelled the car aerodynamically to give the drag coeffiecient and then used that to calculate the hp require to maintain the desired top speed. They would have then said we need this much torque to get us there in a set ammount of time. The torque gives the rate of accelleration, the torque required to keep a car at a set speed is the least torque required, the faster you want to accelerate from that speed, the more torque you require.
on dynos
dyno testers use a 1:1 gear, 3rd or 4th usually because this is the most efficient gear with the least frictional losses in the transmission, which some dynos calculates on overrun/slowdown.
Just gives better readings also dynoing in 1st would create some interesting maths for them and would mean an epic dyno to cope with the torque. eg if you output 400ft/lbs at the fly but dynoed in 1st with a 0.33 1st gear ratio the dyno would have to be capable of dealing with 1200ft/lbs which is very expensive as high torque stresses all the components much more, that and the fact you would struggle for traction on the rollers. However doing it in 4th which is 1:1 would only require a dyno capable of dealing with 400ft/lbs.
Oddly english imperial tools are different to american imperial tools (like gallons which are also different), americans use a/f spanners (across flats) we use the whitworth system, hence why you need different spanners to work on a harley and a triumph (unless its a modern triumph in which case it is metric)
However we are all proficient in both systems which means we have some real odd balls like the weather, when it is hot we talk in farenheit, eg 'its hot today, its gotta be nearly 100' buuut when it is cold we use centigrade eg 'its freezing, its minus 10 outside'
You ask an english man how tall he is and he will say 6ft 1", and if you ask him how much he weighs he will say 13 and 1/2 stone (1 stone is 14lbs btw as americans dont use stone much) and he will buy his beer in pints buuut his pepsi comes by the litre.
petrol is priced by the litre, but cars are sold with economy figures in mpg, the list is endless.
I will say one thing though as a scuba diver i love the metric system, 1 litre of water weighs 1 kg so displace a litre and you have a kilo of boyancy, decend 10 meters and the pressure increases by 1 bar, a 10 litre tank of air charged to 300 bar contains 3000 litres of air at atmospheric pressure, atmospheric pressure being about 1 bar or 1 atmosphere which is the weight of a 1cm x 1cm column of air 1 km tall.
Try doing all that in your head in imperial.
On the whole HP vs Torque thing, torque give you acceleration, however you need hp to overcome things like wind resistance at a said speed. The buggatti veyron has 1000hp so it can maintain such a high top speed whilst generating the downforce required to keep it on the road which creates drag. What the engineers would have done is modelled the car aerodynamically to give the drag coeffiecient and then used that to calculate the hp require to maintain the desired top speed. They would have then said we need this much torque to get us there in a set ammount of time. The torque gives the rate of accelleration, the torque required to keep a car at a set speed is the least torque required, the faster you want to accelerate from that speed, the more torque you require.
on dynos
dyno testers use a 1:1 gear, 3rd or 4th usually because this is the most efficient gear with the least frictional losses in the transmission, which some dynos calculates on overrun/slowdown.
Just gives better readings also dynoing in 1st would create some interesting maths for them and would mean an epic dyno to cope with the torque. eg if you output 400ft/lbs at the fly but dynoed in 1st with a 0.33 1st gear ratio the dyno would have to be capable of dealing with 1200ft/lbs which is very expensive as high torque stresses all the components much more, that and the fact you would struggle for traction on the rollers. However doing it in 4th which is 1:1 would only require a dyno capable of dealing with 400ft/lbs.
rms
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There are some mathematics that are easier in the metric world, money is one of them, but when you start talking engineering the physical world does not compute in nice round numbers.
Acceleration of gravity 9.8 mtrs/sec^2 or 32.2 ft/sec^2, Pi is 3.1416 in both. Angular dimensions 360 degrees, logarithmic tables, triginometry etc etc.
Most of the high tech bits we like to play with have standards that have been developed over many years by the US military. Spherical joints, AN fittings and line, NAS- MS bolts and nuts, washers, Wiggins clamps, 4130 tube. The list goes on and on.
If you want metric K nuts to mil spec standards, you will depend on Airbus Industries having excess to requirements, Imperial available from many sources and a LOT cheaper.
One of my concerns is Allen or Unbrako bolts. There are 2 metric standards for Allen bolts. Both are inferior in physical properties than the 1 imperial/US standard.
It is a double edged sword. Some things I prefer metric, engineering for me is and always will be imperial.
The old argument re bhp/torque
Torque is a static value, as soon as you bring time into the equation you get hp.
200lb/ft (Nm ?) is a force you or I can generate easily, but how fast can we generate it.
Acceleration is the rate at which you can apply the torque, more torque = more bhp = more acceleration.
Also same torqe more rpm = more bhp = more acceleration.
Acceleration of gravity 9.8 mtrs/sec^2 or 32.2 ft/sec^2, Pi is 3.1416 in both. Angular dimensions 360 degrees, logarithmic tables, triginometry etc etc.
Most of the high tech bits we like to play with have standards that have been developed over many years by the US military. Spherical joints, AN fittings and line, NAS- MS bolts and nuts, washers, Wiggins clamps, 4130 tube. The list goes on and on.
If you want metric K nuts to mil spec standards, you will depend on Airbus Industries having excess to requirements, Imperial available from many sources and a LOT cheaper.
One of my concerns is Allen or Unbrako bolts. There are 2 metric standards for Allen bolts. Both are inferior in physical properties than the 1 imperial/US standard.
It is a double edged sword. Some things I prefer metric, engineering for me is and always will be imperial.
The old argument re bhp/torque
Torque is a static value, as soon as you bring time into the equation you get hp.
200lb/ft (Nm ?) is a force you or I can generate easily, but how fast can we generate it.
Acceleration is the rate at which you can apply the torque, more torque = more bhp = more acceleration.
Also same torqe more rpm = more bhp = more acceleration.
StacytheBloke
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As a design engineer i would disagree with that as as there is only really one excepted standard for allen pins (though you are right, there are two) in engineering but we do have a lesser spec as standard buuut more often than not they are adequate and cheaper, the higher specs do go up above that and are easy to get. I wouldn't say one goes higher than the other because you can buy some incredibly high specs from specialists in both forms.
The company i work for was setup by the guys who used to run the english division of an american company so there was lots of unit fun to be had.
Previously i used to work for BAE systems (British Aerospace and we all worked metric, as i was a student at the time i spent some time converting some us parts to metric and converting some metric parts we produced to imperial for the americans. was not fun at all)
As for standards in the uk we have 'welcomed' the change (ish) and have even begun ditching systems we derived such as BSP pipe fittings. And the British Standards are no longer relevant (our equivalent of ANSI) as we have now gone ISO, you can still get the BS standards but if you don't also conform to the ISO standard you are in trouble, but you can ditch the BS standard at will. If you read many BS standards they now say and must conform to ISOxxx, one of the oddities is cars as the BS standards still apply, and pedal bike lights which means that those posh LED lights are illegal in the UK as the standard specifies a fillament bulb, but we all now ignore that.
HP= (rpm*torque)/5252
Torque = (5252 x HP)/rpm
So people are right in saying that the two are directly related however that is assuming you are driving at a fixed rpm which we never are.
Area under the graph of torque against rpm is what is important. Engines that provide good torque at low rpm will out perform engines with the same hp rating but a lesser area under the torque graph. Think of the area under the graph as the average torque through the rev range. Engines are only rated in peak figures.
This all becomes apparent when you try to calculate the optimal shift points for an engine as this is done by trying to equalise the driveshaft torque before and after a shift. Shift early and the torque loss will be large, shift late and there will probably be a torque gain in the shift but a loss of acceleration due to the torque loss prior to the shift.(shift points are often slightly different in different gears)
Drag racers often say that the best point to shift is 10% rpm past the peak hp point. So if you make peak power at 5000 rpm, than shift at 5500 rpm.
Notice how they use torque in all the calcs for shift points because it is that that gives them acceleration.
The company i work for was setup by the guys who used to run the english division of an american company so there was lots of unit fun to be had.
Previously i used to work for BAE systems (British Aerospace and we all worked metric, as i was a student at the time i spent some time converting some us parts to metric and converting some metric parts we produced to imperial for the americans. was not fun at all)
As for standards in the uk we have 'welcomed' the change (ish) and have even begun ditching systems we derived such as BSP pipe fittings. And the British Standards are no longer relevant (our equivalent of ANSI) as we have now gone ISO, you can still get the BS standards but if you don't also conform to the ISO standard you are in trouble, but you can ditch the BS standard at will. If you read many BS standards they now say and must conform to ISOxxx, one of the oddities is cars as the BS standards still apply, and pedal bike lights which means that those posh LED lights are illegal in the UK as the standard specifies a fillament bulb, but we all now ignore that.
HP= (rpm*torque)/5252
Torque = (5252 x HP)/rpm
So people are right in saying that the two are directly related however that is assuming you are driving at a fixed rpm which we never are.
Area under the graph of torque against rpm is what is important. Engines that provide good torque at low rpm will out perform engines with the same hp rating but a lesser area under the torque graph. Think of the area under the graph as the average torque through the rev range. Engines are only rated in peak figures.
This all becomes apparent when you try to calculate the optimal shift points for an engine as this is done by trying to equalise the driveshaft torque before and after a shift. Shift early and the torque loss will be large, shift late and there will probably be a torque gain in the shift but a loss of acceleration due to the torque loss prior to the shift.(shift points are often slightly different in different gears)
Drag racers often say that the best point to shift is 10% rpm past the peak hp point. So if you make peak power at 5000 rpm, than shift at 5500 rpm.
Notice how they use torque in all the calcs for shift points because it is that that gives them acceleration.
rms
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From the 3ltr V8 Cosworth of the 1960's to the last of the 3ltr V10's the max torque has remained very close to the same figure (around 245lb/ft) yet BHP has almost doubled. Car weight is around the same, modern F1's have a lot more aero drag.
Which one accelerates faster? Why?
Which one accelerates faster? Why?
jibbby
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You English have the steering wheel on the wrong side of the cars, also you drive on the wrong side of the roads....Needless to say your round abouts are nuts and the good ole side swipes are in order every time...What's up with that?
I think when the early Americans finally broke away from the British rule, we just did everything the opposite out of spite such as using gallons, liters, pounds, inches, standard as apposed to metric measurements, left side steering wheel, road direction, etc..
Our founding fathers here in the States must of been pissed off about that taxation without representation thing and had to change things up so dramatically....
Anyway that's all history...I always loved the challenge of driving a English made car over there in the UK...Man, I hit the curves and road side edges on turns with the best of them everytime when trying to turn left.....
I guess you guys over in the UK would have that same trouble driving American cars in America and the right turns would surely get a little hairy until your use to driving...
I think when the early Americans finally broke away from the British rule, we just did everything the opposite out of spite such as using gallons, liters, pounds, inches, standard as apposed to metric measurements, left side steering wheel, road direction, etc..
Our founding fathers here in the States must of been pissed off about that taxation without representation thing and had to change things up so dramatically....
Anyway that's all history...I always loved the challenge of driving a English made car over there in the UK...Man, I hit the curves and road side edges on turns with the best of them everytime when trying to turn left.....
I guess you guys over in the UK would have that same trouble driving American cars in America and the right turns would surely get a little hairy until your use to driving...
Lextreme II
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The strangest thing I did when I was in West Indies for vacation few years back. The island was rule by British and the roads are RHD. However, since that island was very close to USA, so their cars were LHD. Imagine driving a LHD car on a RHD road. Took me few days to get use to it.
JBrady
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Power is king.
Power has been given many names including horsepower and Killowatts and therefore it's real nature is often confused because of the calculations to arrive at otherwise random terms such as "horse" power.
Force has been given many names including torque and newton meters and therefore it's real nature is also often confused.
I will now use simplifications to help illustrate these two.
Take a 10 pound hammer and hit a large nail into a piece of wood. The nail goes halfway in.
Now, take an 8 pound hammer and hit another nail THREE times so that the nail is all the way in.
Which was STRONGER? The one hit of the 10 pound hammer or the 3 hits with an 8 pound hammer?
Power is how rapidly you can apply force.
This is why a car with a constantly variable transmission (CVT) will operate the engine at peak POWER for peak acceleration. There is MORE force delivered during that time it is just that the force is in smaller units that at peak torque.
Remember, you can multiply torque (force) with gearing but you cannot multiply power. Power is king.
Power has been given many names including horsepower and Killowatts and therefore it's real nature is often confused because of the calculations to arrive at otherwise random terms such as "horse" power.
Force has been given many names including torque and newton meters and therefore it's real nature is also often confused.
I will now use simplifications to help illustrate these two.
Take a 10 pound hammer and hit a large nail into a piece of wood. The nail goes halfway in.
Now, take an 8 pound hammer and hit another nail THREE times so that the nail is all the way in.
Which was STRONGER? The one hit of the 10 pound hammer or the 3 hits with an 8 pound hammer?
Power is how rapidly you can apply force.
This is why a car with a constantly variable transmission (CVT) will operate the engine at peak POWER for peak acceleration. There is MORE force delivered during that time it is just that the force is in smaller units that at peak torque.
Remember, you can multiply torque (force) with gearing but you cannot multiply power. Power is king.
jibbby
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Torque wins races.....
JBrady
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You are not getting it.
Review the above, think about it.
The hammer example clearly shows the 10 pound hammer doesn't finish the race at all.
The 8 pound hammer wins with LESS force (torque).
jibbby
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I get what your saying John... Let me put it this way to you...
You have two cars both weight the same both are geared to suit each engines power.. Both drivers are the same...
One car has 300whp and 500 ft. pnds of torque
Second car has 500whp and 300 ft. pnds of torque
Which car would win? Short distance the torque wins long distance maybe the horse power wins...Right or wrong?
You have two cars both weight the same both are geared to suit each engines power.. Both drivers are the same...
One car has 300whp and 500 ft. pnds of torque
Second car has 500whp and 300 ft. pnds of torque
Which car would win? Short distance the torque wins long distance maybe the horse power wins...Right or wrong?
JBrady
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Completely wrong.
OK, I will take the time to explain so please read and do the simple math to understand.
GEARING makes all the difference.
Let's make this easy and say that a TIRE RPM of 800rpm = 60mph
Now, we need to find out what ENGINE rpm is needed to reach any given speed. If we want 30mph that would of course need 400rpm at the wheels.
OK, your 2 examples work out this way.
300tq and 500hp means the engine is turning 8750rpm to make 500hp.
500tq and 300hp means the engine is turning 3150rpm to make 300hp.
Gear each car to be at peak HP at 30mph and you get 21.875 to 1 ratio for the 500hp and 7.87 to 1 ratio for the 300hp.
Now, multiply each engines torque by the gear ratio to find out the torque available at the wheels for each engine.
500hp/300tq: 300 x 21.875 = 6563 lb/tq at the wheels
300hp/500tq: 500 x 7.87 = 3938 lb/tq at the wheels
So, at the wheels, the 500hp engine enjoys 2625 pounds of torque at the wheels MORE than the 300hp engine.
In fact you could gear the 500hp engine to be at peak power at 45mph and it would STILL make 437 more torque at the wheels than the 300hp engine at 30mph!!!
I repeat... POWER is king.
JBrady
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One of the big reasons for confusion here is that Dynojet dyno's (and other chassis dynos) usually correct wheel torque back to engine torque. The fact is that the gears multiply the engine torque. Even in 4th gear (typically a 1 to 1 transmission ratio) a car with a 3 to 1 final axle ratio will still have 3 times the engine torque at the wheels. With a 3 to 1 first gear selected it has 9 times.
BTW, this is how a car is able to do a wheelie. You must have more pounds of force than the front of a car weighs in order to lift the car. Since there are very few cars with under 1000 pounds of front weight and very few cars with 1000 pounds of engine torque it would be impossible with out multiplying with gears.
So yes, in the above example the 500hp car would in fact have over 6500 pounds of force at the tires. This is how you calculate how MUCH torque is hidden in the power figure. This is why you can multiply torque but you cannot multiply power. Peak power has the peak amount of torque for ANY given speed. This is why CVT cars operate at peak power. Case closed.
BTW, this is how a car is able to do a wheelie. You must have more pounds of force than the front of a car weighs in order to lift the car. Since there are very few cars with under 1000 pounds of front weight and very few cars with 1000 pounds of engine torque it would be impossible with out multiplying with gears.
So yes, in the above example the 500hp car would in fact have over 6500 pounds of force at the tires. This is how you calculate how MUCH torque is hidden in the power figure. This is why you can multiply torque but you cannot multiply power. Peak power has the peak amount of torque for ANY given speed. This is why CVT cars operate at peak power. Case closed.
StacytheBloke
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OK an example to throw in the mix. Topgear in the uk did a drag race, between a 1.6 litre fiat stilo estate and a mitsi evo 8 fq400, both started in top gear at 30mph. Then they drag raced without gear changes down a 1.7 mile runway.
The fiat won
http://www.metacafe.com/watch/203232/evo_vs_fiat_stilo/
The mitsi has no bottom end torque due to turbo lag (it also has low bhp too but even with low bhp the figure is still higher than the fiat right across the rev band. The evo has 4 times the bhp (401) so even if top gear was 4 times higher, if torque wasn't the issue in giving acceleration you would expect it to win.
(the car was quickly dropped because it was "undrivable")
Extreme example but proves a point.
The fiat won
http://www.metacafe.com/watch/203232/evo_vs_fiat_stilo/
The mitsi has no bottom end torque due to turbo lag (it also has low bhp too but even with low bhp the figure is still higher than the fiat right across the rev band. The evo has 4 times the bhp (401) so even if top gear was 4 times higher, if torque wasn't the issue in giving acceleration you would expect it to win.
(the car was quickly dropped because it was "undrivable")
Extreme example but proves a point.
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