Better parametric engine model

[Smarty]

The current engine model in ETS2, unless I'm mistaken, has one parameter that affects the simulation: torque. There are information fields that are used in game to tell the player more about the engine characteristics, but these don't actually affect the behaviour of the vehicle in an appreciable manner. While many modern diesel engines have relatively 'flat' torque curves, this isn't always the case.

There are a fair number of engine makes in North America and they don't all behave in the same manner - especially some of the old two-stroke diesels. I would like to see the engine model expanded to allow modders (or even SCS) to capture the character of specific engines within reasonable parameters. What I propose is that the engine definition be amended as follows:

• Idle RPM (integer); sets the speed that the engine idles at
• Governed RPM (integer); sets the maximum speed that the engine will run at
• Fuel type (string); sets which fuel is used (price, availability, density) if the def system is extended to allow this
• RPM breakpoints (int array); sets RPMs for other array parameters
• Torque (int array); sets the torque at a given RPM
• Fuel consumption (short array); sets the fuel consumption rate at a given RPM
• Damage rate (short array); multiplier for base engine damage rate at a given RPM (code would need to relax this when the engine is only under partial load)
• Exhaust colour (rgba array); colour (rgb) and opacity (a) of exhaust particle emitter(s) at a given rpm

The game can linearly interpolate between the array values. This system would also allow for gasoline, CNG, or even turbine engines to be functional and convincing in the game.

[Cadde]

Yes, i would like it in ETS 2 as well. It's always a good idea to let users tweak the curves to what THEY believe is realistic. Hence one can reduce all the back and forth on truck too powerful and truck too weak since patch X.Y.Z that inevitably happens every time SCS changes something, no matter how small.
Heck, even when SCS hasn't changed a single thing people will claim they have and ask SCS to fix it.

I'd say, introduce sliders and graphs for each and every engine so users can customize it from within the game...

[Smarty]

I'm not so sure about the sliders aspect; I expect it would be tough to make a robust model of the cost that would balance against the existing engine cost model. Graphs sound like a decent idea though. It gives the player a better understanding of the engine characteristics so they can make an informed decision when selecting their engine. In real life you'd have a spec sheet with the torque curve and the brake specific fuel consumption.

I've been thinking about this some more and I think two more parameters would be needed to complete the engine model:

• Turbo inertia (short): a time constant to model the 'turbo lag' (defined as the step response from 'normally aspirated' maximum torque to rated maximum torque in seconds)
• Turbo torque factor (short): the ratio of maximum rated torque to 'normally aspirated' maximum torque (i.e. a value of 1.0 models an engine without a turbocharger; possibly with a supercharger such as an NHRS Cummins)

This addition might be a little trickier than the rest because the torque output is now a differential equation rather than an interpolation. That said I do believe this will add some needed challenge to the garage portion of the game. If the player is running short-haul they might make out better with a less powerful (overall) but more responsive engine because they have to get moving from a stop more often. Conversely if the player is doing long haul they may find the added maintenance cost and slower response are outweighed by their ability to go full freeway/turnpike speeds while loaded and not be slowed down as badly by hills.

I don't think it's a big enough change to wreck gameplay for anyone but it should definitely keep things interesting for the enthusiast crowd.