How does an engine work? Check this!

[JohnC]

Ahh, that wankel engine is really facinating I somehow can't imagine that piston to be as durable as the radial engines though...

So basically, Diesel is mainly the same, except the ignition is a bit different and greater amount of air is sucked in to a Diesel engine, am I right? Are there any well known diesel additives to decrease the black smoke coming from the exhaust?

You're right, Diesel Engines operate with a great amount of air, in fact work better with turbochangers and we often talk about "TurboDiesel". Diesel Engines works even better with turbocharges + intercooler.
For the black smoke there are two possibilities:
1) the Injectors are dirty
2) Check the EGR valve, which is the main cause.