Or your car's exhaust pipe. How does it work? I have heard many a theory, ranging from "running too rich" to "straight through exhausts (no cats)"...

Tell me the truth, gentlemen!

 

The rotary engine is inefficient; meaning there is a bit of unburned fuel going out the exhaust port and through the exhaust. When you are decelerating from a high RPM (>6000) there is enough gas being sucked through to become ignited, and usually shoot a big-*** flame out the tailpipe. If the engine is running real rich, or if there are many holes in the exhaust, then the backfires will be more frequent and violent. A straight pipe produces more flames due to a lack of restriction.

 

Oh, and to compare and contrast with piston engines, they will shoot flames also. Im sure you notice race cars shooting flames all the time (Grand Am sports cars, Le Mans sports cars, hell Top Fuel drag cars) You just need massive combustion chamber pressures and usually a lot of ignition advance, and 116 octane race gas helps too.

 

Simple over lapping of the intake and exhuast ports..much more so on ported engines