I see the problems involved so I only advocate the following:
Mixture only becomes a problem when a plane reaches critical altitude, since almost all flyables have a supercharger or turbocharger.
1. Correction of the MW50 problem.
2. Higher resolution mixture control.
3. The adding of engine knocking/detonation/whateveryoucallit. This can be done quite easily, every plane has a maximum allowable manifold pressure, beyond that a sound sample could be added, together with a slow decrease in engine power, say 1% per minute for a slight boost over the red line, to 10% p/m loss of power for let's say 20 inches above the red.
And a warning on the HUD.
This is where the water injection/MW50 comes in, where instead of calculating complex matter IL2 never had to worry about like intake manifold temperature, switching on these systems virtually just lowers the manifold pressure by substracting a predefined value, but not for the pilot who still sees the original value on the gauge. Once the tanks holding the MW50 or water are empty, the predefined value is added again and engine knocking commences. That's pretty easy, compared with implementing radio navigation
Since most planes do not have these systems, other planes can have a small bit of this effect by increasing the mixture/Erhöhte Notleistung, essentially extra cooling the charge before it enters the cylinders, at the cost of higher fuel consumption. That is why I would like to have mixture control with a better resolution, seen on the HUD as percentages above or below "normal" (in technical terms:
http://en.wikipedia.org/wiki/Stoichi...f_common_fuels )
These solutions only work until critical altitude is reached and overboosting values cannot be reached anymore. Above that rich mixture or Erhöhte Notleistung become a burden quite quickly, still cooling a bit but lowering performance steadily with altitude.
This is also why running with high manifold pressure, a too lean mixture again leads to engine knocking, since the cooling effect of the vaporization of the fuel is less.