# Modelling Torque Discussion

I’m making this post in preparation of doing a full suggestion. For modelling torque and torque converters.

As far as I’m aware, the current modelling of the drivetrain in game uses 1 power value, this is presumably supplied at all RPM’s?

Ideally, a full torque graph should be used, in the same way jet engines in game have thrust map with speed.

Nearly every engine in game has a known maximum power and maximum torque, therefore every engine has 2 known datapoints, inbetween, estimated data can be used where it is not publicly available, this is the same for jets, and can be corrected if needed for the required performance. The added benefit of this, is that different engine types produce differing torque curves; this adds an extra level of realism to the game, gas turbines will perform differently and show their benefits over diesel engines in certain conditions and vice versa.

As for torque converters, a similar technique can be used, a torque converter acts as a fluid coupling between the engine and drive. However the lesser known benefit of a torque converter is torque multiplication. This occurs at the “stall point”, when the drive/vehicle is stationary. At this maximum point, torque can instantaneously increase by upwards of 2 times, for a leopard 2, it is 2.5X, for a Challenger 2, it is 3.5X. This gives tanks extra grunt when the engine speed is high relative to the speed of the connecting transmission.

In game, torque converters are replaced by adding extra gears to vehicles, keeping the engines at a roughly constant rpm when accelerating. However these gears are evenly distributed, the effect of a torque converter is only at low speed/early gears, above these low gears the converter is locked. Meaning these additional high speed gears are meaningless anyway.

As with the torque curves, the maximum multiplication effect can be given a default value for all tanks, and changed when public data is able to prove otherwise, or it is needed to achieve verified performance. The multiplication effect decreases to 1X as the engine rpm comes closer to the transmission input rpm. A generic curve can be used to account for this.

This will give vehicles a more dynamic drive performance, and improve performance in some areas significantly.

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I’m just a bit confused at how the “speed ratio” for torque converters works.

So for a torque converter, there is two parts, the input and output side, the input is connected to the engine, the output connected to the transmission, a 1:1 ratio means the input and output are at the same speed, a 0.5:1 ratio means the output is half the of the input and so on. 0 is known as the stall point where the output speed is 0.

Ah, I see.

So from my understanding and a bit of online reading, the “pump” is always spinning because it is connected to the engine, at low speeds the pump will be spinning faster than the “turbine”, which is directly connected to the transmission, and due to this the stator basically does some fluid magic with the fluid hitting the blades in a very specific way and the output torque gets multiplied.

I knew torque converters multiplied torque in some way, I just didn’t really get why that was the case

ya the mechanics of it is kind of odd, but quite cool.

It would certainly be interesting to see how late war and post war US vehicles would be like with actual torque converters instead of just… doubled gears.

I’m more afraid that something would be screwed up once Gaijin attempted it though.

question is how hard would it be to model and implement

Not particularly difficult, I’d imagine it would be of similar technical difficulty to aircraft flight models.