How does the torque affect a vehicle?

PS or Nm? Power or torque, which is more important?

With modern turbo engines in our road traffic, whether turbo gasoline or turbo diesel, the engine delivers its maximum torque over a wide speed range. In turbo gasoline engines, the maximum torque often starts at around 1,500 and is maintained up to around 4,000 - 5,000 revolutions / min. The motor has the same power in this range (1,500 to 5,000 revolutions / min); which means that it doesn't matter whether I press the accelerator pedal at 2,000, 3,000 or 4,000 rpm in 2nd gear, the force that accelerates the car and pushes me into the seat is the same. It is the same with turbo diesels, where the speed range and the range of the maximum torque are somewhat narrower (approx. 1,500 - 3,500 revolutions / min). Classic gasoline engines, also called naturally aspirated engines, are becoming increasingly rare in the age of downsizing. These naturally aspirated engines have a different engine or torque characteristic. The maximum torque is usually around 60 - 70% of the maximum engine speed, i.e. at a point between 3,500 and 5,000 revolutions and is only held for a short time. Before that, the torque from approx. 1,500 revolutions is approx. 70 - 85% of the maximum torque and increases to the maximum torque. After reaching the maximum torque, it often drops very slightly and decreases more sharply from the point at which the highest number of horsepower has been reached. It is the same with turbo engines: As soon as the highest speed is reached, at which the maximum torque is applied, the torque drops. From precisely this point on, both suction gasoline and diesel engines accelerate at roughly the same rate. Often one then has the feeling that “from this point there is not much more”. Then unfortunately there are often people who claim that a car only really accelerates from around 4,500 - it only seems like that to these people. The physics as well as the real data often show the opposite. It is only a subjective feeling, because then z. B. the engine is particularly loud. As soon as the point of maximum torque is reached or exceeded, a car does not accelerate faster - why? I will explain that to you in this article.

Often the inaccurate specification of the maximum torque leads to confusion at round table discussions, in which one likes to compare cars, the same model with a different engine (often gasoline vs. diesel).
“A: My car X has 250 Nm of torque. It's really fast.
B: Cool, I have the Car X too - mine has 200 Nm of torque, but it accelerates faster than yours.
A: Nonsense, mine has more torque, so it accelerates faster. "

A's car X has a turbodiesel that produces 250 Nm at 2,000 to 3,000 revolutions (250 Nm at 3,000 revolutions result in 79 kW / 107 hp). The maximum power is 120 hp at 4,000 rpm (corresponds to 210 Nm at 4,000 rpm).
B's car X only manages 200 Nm at 5,000 rpm (corresponds to 105 kW / 142 hp at this speed) and a maximum of 171 hp at 6,500 rpm (corresponds to 185 Nm at 6,500 rpm).
So who is right, A or B? A's car clearly has more torque, but is it that meaningful and really faster?

So that you can now compare better, you just look at the number of horsepower and you can better imagine which of the two cars accelerates better. However, this comparison value is only meaningful if it is the same car or if it has the same or very similar parameters.

How can it be that a car with less torque accelerates faster?
The higher torque of A is only available over a narrow speed range and, of course, there is also the gear ratio. I have the following example for this:
Let's assume we have two almost identical cars as in the example above. They only differ in the motor or the associated gear or the gear ratio.
Both reach 50 km / h in first gear and 100 km / h in second. However, the gear ratio now changes the power that is emitted by the engine and ultimately arrives at the wheels via various parts. With car A, we remember with 250 Nm torque, we drive 50 km / h or 100 km / h in first or second gear at 5,000 rpm.
With Auto B (200 Nm torque) the motor turns at the same speeds and gears, but at 7,000 revolutions. What does it mean now? It is said that the gearbox of B has a shorter gear ratio. This means that less power is needed to accelerate the car or, with the same torque, more power is transmitted to the wheels. This is why B's car can accelerate better than A, provided it also has more power. So if I use the same force with a shorter gear ratio, I accelerate more. You can test that on the motorway, for example. If you e.g. If you want to accelerate at 100 km / h, you will notice the difference whether you are trying out 4th gear or 6th gear. The 4th gear has a shorter ratio and enables better acceleration. You can also remember your own bike that had gears. If you wanted to start in a higher gear, you had to pedal very hard to get any faster. You always achieved a very high speed for this. On the other hand, there were the small gears where you could get out of place very quickly or go uphill very well, but the top speed was very limited. It is the same with the car with the gears.

In conclusion, one can say that the longer gear ratio, especially with turbo diesels, almost dissolves the extra torque.

What is more important now? Nm or power?
Here comes the standard legal answer again: It depends.
Vehicles that want / should pull a trailer, for example, need a lot of torque in the lower speed range. Why? Quite simply, through a higher torque at a low speed, you have comparatively more power than with an engine without turbocharging. In the case of a naturally aspirated engine with less torque, the power is only available at a higher speed, or perhaps the power at a very low speed is insufficient to be able to accelerate sufficiently. We remember that power is a product of torque and engine speed. In an everyday car, the torque is therefore not necessarily as important as it is often described.
You can of course accelerate much better with turbo engines from the ranges between 1,500 and 3,000 revolutions. In the speed range beyond that, it hardly makes any difference in terms of acceleration whether turbo or not, since between suction gasoline and turbo gasoline engines from approx sinks. So if you want to save yourself having to downshift on the highway, turbo engines with high torque are better suited than naturally aspirated engines that turn very high. These still have their raison d'etre. Their advantage is clearly that they work without a turbo, which in the long term often causes problems, has to be repaired, gives off a lot of heat, etc. Naturally aspirated engines are not as heavily stressed during normal driving and are more durable than turbo gasoline engines, for example.