It's the same as a lever, ie an ant can move a one ton weight if it has a long enough lever, but an elephant might not need a lever.
Similarly, a 1hp and 100 hp engine can produce the same torque at the wheels given the right gear ratio. The 100 hp might have direct drive (ie the elephant) while the 1hp would need a 100:1 ratio (ie the ant on a long lever) to get the same torque at the wheel, but it would be at 1/100 of the speed.
richard_leeds wrote:It's the same as a lever, ie an ant can move a one ton weight if it has a long enough lever, but an elephant might not need a lever.
Similarly, a 1hp and 100 hp engine can produce the same torque at the wheels given the right gear ratio. The 100 hp might have direct drive (ie the elephant) while the 1hp would need a 100:1 ratio (ie the ant on a long lever) to get the same torque at the wheel, but it would be at 1/100 of the speed.
What do you mean by speed? Are you referring to rpm or ds/dt?
Im not really sure what point you are trying to make, if you are arguing that all engines make the same "driving force" at the wheels then you are clearly mistaken otherwise we would have a bunch of 1.6Ts making 80hp and winning via a very clever 8 speed gearbox while using minimal fuel.
Clearly the new power units are able to ask more from the tyres under acceleration than the v8s were, it is clear to see and the drivers are confirming it.
Im not really sure what point you are trying to make, if you are arguing that all engines make the same "driving force" at the wheels then you are clearly mistaken otherwise we would have a bunch of 1.6Ts making 80hp and winning via a very clever 8 speed gearbox while using minimal fuel.
Clearly the new power units are able to ask more from the tyres under acceleration than the v8s were, it is clear to see and the drivers are confirming it.
I think you may have missed the point here. What we're saying is that, in and of itself, engine torque isn't an especially important contributor to wheel torque. An engine's horsepower, on the other hand, is absolutely critical, because it's the car's power-to-weight ratio that largely determines just how fast it can be.
Power is everything, because it's work. With enough work, you can do anything.
Otherwise, yeah, I could still take that 80-bhp engine and make absurd amounts of wheel torque, if I'm prepared to accept the very low output speeds that would result. Hypothetically, I could have 10,000 lb-ft of wheel torque if geared for it, but a tortoise might wind up being a faster option.
richard_leeds wrote:It's the same as a lever, ie an ant can move a one ton weight if it has a long enough lever, but an elephant might not need a lever.
Similarly, a 1hp and 100 hp engine can produce the same torque at the wheels given the right gear ratio. The 100 hp might have direct drive (ie the elephant) while the 1hp would need a 100:1 ratio (ie the ant on a long lever) to get the same torque at the wheel, but it would be at 1/100 of the speed.
Yea but how do you get the assumption that two engines, vastly different, with vastly different gear ratios will output the same torque on the wheels?
You are saying "given the right gear ratio", the gear ratios on the V8 changed every single race while the ones today are fixed but with the addition of one more gear.
Surely the torque output on the wheels on the V8 car alone would differ from race to race?
I just cannot understand how it all equates to the same exact torque output on the wheels among two completely different cars with completely different gearboxes with completely different gear ratios.
Not saying anyone of you are wrong, far from it, i just don´t understand it that´s all.
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SectorOne wrote:
Yea but how do you get the assumption that two engines, vastly different, with vastly different gear ratios will output the same torque on the wheels?
You are saying "given the right gear ratio", the gear ratios on the V8 changed every single race while the ones today are fixed but with the addition of one more gear.
Surely the torque output on the wheels on the V8 car alone would differ from race to race?
I just cannot understand how it all equates to the same exact torque output on the wheels among two completely different cars with completely different gearboxes with completely different gear ratios.
Not saying anyone of you are wrong, far from it, i just don´t understand it that´s all.
Other have already described how equal torque at the wheels can be achieved with different engines. So I won't comment that.
But IIRC with V8 they had a set of declared ratios for the season and although could change gearing from race to race it was limited within the approved sets of a given team.
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Dragonfly wrote: Other have already described how equal torque at the wheels can be achieved with different engines. So I won't comment that.
Yea they said "right" gear ratios. Which makes no sense since even the V8 had multiple ratios.
Dragonfly wrote:But IIRC with V8 they had a set of declared ratios for the season and although could change gearing from race to race it was limited within the approved sets of a given team.
Yea but they changed. And thus, from what i´ve read in this thread, so did the torque output.
So now when comparing to a car that´s not even running the same engine or gearbox i don´t think you can just casually say the torque output of these two cars is identical.
Basically an assumption that both cars have the right gear ratios that would make the cars output the same identical torque output.
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Lets say the car is travelling at a road speed such that its wheels are turning at 600rpm...
Your engine is turning at 8000rpm, and putting out a torque of 250lbft, (that's a power of 380bhp). To match the engine to the road wheel you need an overall gear ratio of 13.3:1 (8000rpm/600rpm=13.333) That means the torque at the road wheels is 13.3x 250lbft = 3333lbft.
Now take another engine in the same car, travelling at the same speed. Lets say it is turning at 16000rpm and has a torque of just 125lbft at the flywheel; that is also a power of 380bhp. To match the road wheel speed to the engine speed you now need a ratio of 26.6:1. That means the torque at the road wheels is 26.6x 125lbft = 3333lbft
i.e. with two engines having the same power and travelling at the same speed (with the same size wheels), they will have the same torque at the wheels regardless of what torque they have at the flywheel, and regardless of the gear ratio used to match the engine to road wheel rpm.
Now the new engine make about the same peak power... but the power curve is very flat, so they generate more power (and hence torque at the road wheels for a given road speed) at low rpm; and that is what the drivers are commenting on; at low rpm the car will spins its wheels much easier because it has very high low rpm power compared to the old engines....
Last edited by machin on 18 Mar 2014, 22:41, edited 1 time in total.
I'll try to explain it, but this one of those things where one must think in formulas.
Power = force * speed is something one remembers from school, in any case the formula was there, in one form or another. The angular equivalent of it is
Power = torque * speed. The units are changed, but the concept is the same.
Now think that the conservation of energy is a law of nature (so it P=f*s), but there is no such thing as the law of conservation of torque. Since power is the change in energy per unit of time, there is such a thing as the conservation of power.
The power the engine is doing, say, as measured in the dyno, is the same power available to the wheels, bar for small losses. If the new engines produce 600HP at 10000RPM, the wheels will also have 600HP available. Whether they can use it all or waste it as wheel slip is another matter. But he engine produces 600HP at 10000RPM in 4th gear, and 600HP at 100RPM in 6th gear, and also 600HP at 10000RPM in 8th gear (lets call that scenarios A, B and C). The power is a fundamental property of the engine, that at that RPM manages to burn so many grams of fuel per second. In those three scenarios the engine has the same power and the same angular velocity, and as consequence also the same torque at it's axle.
Since energy and power are conserved, the different gears do not change the power available. The gear set receives 600HP from the engine and outputs 600HP to the wheels. A gear is a machine that trades torque for RPM. The shorter gears (1st gear) output less angular velocity, and hence more torque. The product angular velocity * torque (= power) stays constant. 8th gear in comparison outputs a higher angular velocity and less torque.
This is necessary because 8th gear is designed to be used at high speed. High speed means high angular velocity in the wheels, and hence low torque in the wheels. Lets go back to the three scenarios in 4th, 6th and 8th gear at 10000RPM. The car is doing, say, about 160Km/h, 250Km/h and 320Km/h. In all cases the wheels have the same radius and the same power available. But in 8th gear the angular velocity of the wheel is twice as high. Since Power = torque * speed, it follows that torque at the wheels must be twice as small.
To summarize, scenarios A, B and C see the same torque and angular velocity at the engine's axle, but different angular velocities and different torque at the wheels. Because the gears have done their function of trading torque for angular velocity.
Now, lets compare the 2013 and 2014 cars. Our three scenarios now correspond to a V8 engine running at 15200 RPM in, say, 3rd, 5th and 7th gear. The V6 engine produced about 600HP at 15200 RPM, no matter whether it was in 3rd, 5th or 7th gear. Its angular velocity at the axle was higher than that of the V6, but the power the same. Correspondingly, torque at the axle was less in the V8 to keep torque*speed constant.
But at the wheels, the V8 car had 600HP available at 160Km/h, at 250Km/h and also at 320 Km/h. Those wheels where more or less identical to the current ones, so angular velocities of the wheels were the same with a V8 as they are now with a V6 at the same car speed. Same power at the wheels and same angular velocity at the wheels -> same torque at the wheels.
Comparing the V8 and the V6, the V8 had more RPM and less torque at the engine's axle. But since the RPM (angular velocity) of the wheels is the same in 2013 as in 2014, the gears linked to the V8 have mediated a larger reduction in angular velocity from engine to wheel, and correspondingly a relative increase in torque from engine axle to wheel. And voila, the lesser torque at the engine of the V8 has transformed into the same torque at the wheels as for the V6.
Because it must, because both in 2013 and in 2014 you had about the same power available at the engine, and about the same power available at the wheels, and the same type of wheels, and the same car speeds.
Torque at the wheels depends on the power of the car (same as the power of the engine) and the car's speed. The gears' very function is to decouple power at the engine from power at the wheels, so the wheels can get the angular velocity they need to give the car the linear velocity it needs, no matter the engine's RPM. With a CVT the last sentence would be strictly true, with the current gear boxes,we have 8 conversion factors available.
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I hope it is clearer now. A very long explanation, but I am not sure at which point in the logic chain everyone gets lost. I also hope that it is clear that I made the V6 and V8 engines equally powerful for simplicity. In reality the V8 probably had a tad more peak power, and a lot less off-peak power than the V6 + KERS + HERS.
But it is true that in 2014 the cars tend to produce more wheelspin, and it is true that they do that because they have more torque... at the wheels (they also have more torque at the engine as they have lower RPMs, but that is irrelevant). But not all the time. At high (for 2014) RPM, they have about the same torque at the wheels that they had at high (for 2013) RPM with the V8. But the V8s spent a significant part of the acceleration phase at lower than peak RPMs, where they lost 20-30-40% of its power, and hence 20-30-40% of torque at the wheels. In the same scenario the 2014 engines only lose 5-10% power thanks to a flat power band, and hence they only lose 5-10% torque at the wheels. End effect, at many points there is 20-30% more torque at the wheels (at other points, they have the same). But in those cases, they only have more torque at the wheels because they have more power, the gears made the torque at the engine an afterthought. Add the lesser downforce, and of course they get wheels spin easily.
As many people tried to express before. Power is important, you want to have as much of it as you can, power moves your car. A Dremel, with all its torque, wont. Power makes your car a winner. And angular velocity is important, the angular velocity of the wheels determines the linear velocity of he car. Angular velocity takes you to the finish line. The more you have, the faster you go. Torque... you adjust as needed with those things called gears.
Easiest way to xplain this is to begin with section 2.3 Work and Energy.
- Work or Energy is defined as Force times displacement; W = F * delta r
As Power is Energy per time unit;
- Power is defined as Force times Velocity; W/t = F * delta r/t, or P = F * v
In the case of a Formula 1 car;
- Power is what is delivered from the power-source ICE + MGU-K
- Force is the traction-force on the rear tires' contact-patch.
- Velocity is the car's speed.
Why; Power (Watt) = Traction-force (Newton) * Speed (meter/second)
Gives; Traction-force = Power / Speed
What happens between Power-source and contact-patch, "torque" or whatever, is irrelevant.
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In the same scenario the 2014 engines only lose 5-10% power thanks to a flat power band, and hence they only lose 5-10% torque at the wheels. End effect, at many points there is 20-30% more torque at the wheels (at other points, they have the same). But in those cases, they only have more torque at the wheels because they have more power, the gears made the torque at the engine an afterthought. Add the lesser downforce, and of course they get wheels spin easily.
Just trying to make sure I understood everything correctly.
So, because of the flat power band and because Power = torque * angular velocity, this results in the torque graph having a descending slope, rather than what is normally quoted as a predictable racing car which has a flat torque curve. In the end, does it mean that the initial throttle application at 10k RPM will put the highest force on the tires, thus much easier resulting in wheel spin and basically this is what some drivers are complaining about? I'm talking about torque because, as I get it, this is the force that ends up turning the tires, thus the primary reason for wheel spin.
richard_leeds wrote:Yes, if matched with the right gear ratios. As Archimedes said "Give me a lever long enough and a fulcrum on which to place it, and I shall move the world." It's just the same for a tiny engine with an appropriate gearbox, albeit with very little displacement !
It really is a simple as Power = torque * speed. If you can change the speed then you can have any torque you want. Of course extreme cases are hypothetical because inertia, tolerances and friction will mean a tiny engine would be unlikely to turn the gearbox.
This would be correct for every engine AT THAT PARTICULAR RPM, however while they may produce the same max hp at that rpm, the power (as a function of torque and rpm) at lower rpm will be greater at a low rpm. Therefore while at full power rpm the 2014 engines may produce similar torque numbers to the wheels, the torque numbers lower down the rev range at 10,000 9000 and 8000 rpm will be much higher than the equivalent reduction in rpm vs loss of torque for the older V8's
