Two engine drivetrain

I can't figure out how I can use two engines with the current powertrain. I'm driving the front wheels with one engine and the rear with another, but everytime I have two engines at the same time, the game gives me a fatal exception. Is it that I can't have both attached to the dummy controller? What do I have to do to get two engines at the same time?

 

Diamondback has mentioned that you need custom vehicle controller to handle more than one engine, because default one don't know what to do with second engine.

However I haven't read anyone writing about how that actually would happen, what files needed, where to reference, what are the keywords etc.