SpudFiles

I have noticed a plethora of cannons are starting to incorporate fans in the combustion chambers. Could someone shed some light on the purpose of this?

Also, if you happen to have some links to some guides of how to do it I would appreciate that.

there to mix the fuel, then to exhaust the burnt gasses

Fan
Fan Controller

Like what lucy said, they mix the fuel (if you're using a liquid) and blow out any vapors you may have floating around in there. As for installing them, I have no idea.