Educational Piston Engine model diesel or gas

Showing some reference images from my LEGO LDI-6 (LEGO Diesel Inline 6) engine. Here it shows the 2:1 ratio gears for the camshaft. Also gears for the radiator fan and water pump.

A key feature would be working valves using springs and rocker arms if it is a push rod engine like this. No need for pushrods in an overhead cam engine, but pushrods makes the model more mechanical :)

One unrealistic part in the engine would be the LEGO piston. Pistons are supposed to be round, but this is LEGO. :) I would recomend that this part would be a special part like the Auto engines had to prevent friction.
The piston for the LEGO version should be 4x4

I have developed my piston better than this one, but I need to take a picture of it soon. It uses a 4x4 plate with 2x2 hole in the middle. Available in red in Pick a Brick.

Detail is key to a great model. Here is the fuel filter. The long silver hose to the bottom is one of the hoses for the radiator.

The last part, is functionality. Whats a model engine without it working?
Here is a video of my LDI-6 working with a LEGO 9V motor with a ol' LEGO train speed regulator. The LEGO version would use Power functions motor and a knob to adjust the speed.