When the the flux capacitor radiats heat into the fuel lines
Scavenging
combustion chamber area
three types of scavanging pocesses: 1) Cross Scavanging 2) Loop Scavanging 3) Uniflow Scavanging
The upstroke of a two-stroke engine has only one function: compression. The downstroke is where power, then exhaust, then intake occur. This is the greatest animation I've seen for explaining a two-stroke engine: http:/www.animatedengines.com/twostroke.shtml
A two-stroke engine is an internal combustion engine that completes the process cycle in one revolution of the crankshaft (an up stroke and a down stroke of the piston, compared to twice that number for a four-stroke engine). This is accomplished by using the beginning of the compression stroke and the end of the combustion stroke to perform simultaneously the intake and exhaust (or scavenging) functions. In this way, two-stroke engines often provide strikingly high specific power, at least in a narrow range of rotational speeds. The functions of some or all of the valves required by a four-stroke engine are usually served in a two-stroke engine by ports that are opened and closed by the motion of the pistons, greatly reducing the number of moving parts.
Scavenging is the process for pushing out burned gases and drawing in fresh air for the next cycle. It requires the exhaust to be tuned correctly for the specific engine to get the most benefit. A good example would be expansion chambers on a two stroke motorcycle engine. They're designed to help suck out the exhaust gas, thus helping pull in (scavenging) the fresh charge.
Explain the advantages of four-stroke engine over two-stroke engine
in my opinion a two stroke engine is a better quality engine as compared to a four stroke engine!
Detroit diesel engine is an example of two stroke engine
two stroke
You freeze up the engine
A two stroke engine has half the strokes of an otto (or four stroke) engine, therefore it takes two crankshaft roatations to complete a cycle on a four stroke engine and only one revolution in a two stroke engine. There are several types of two stroke engines, the different types have to do with how the receive the air/fuel mixture, also you have two stroke diesel engines.