Starting at TDC
Main article: 2-stroke engine
The defining characteristic of this kind of engine is that each piston completes a cycle every crankshaft revolution. The 4 processes of intake, compression, power and exhaust take place in only 2 strokes so that it is not possible to dedicate a stroke exclusively for each of them. Starting at TDC the cycle consist of:
Power: While the piston is descending the combustion gases perform work on it?as in a 4-stroke engine?. The same thermodynamic considerations about the expansion apply.
Scavenging: Around 75° of crankshaft rotation before BDC the exhaust valve or port opens, and blowdown occurs. Shortly thereafter the intake valve or transfer port opens. The incoming charge displaces the remaining combustion gases to the exhaust system and a part of the charge may enter the exhaust system as well. The piston reaches BDC and reverses direction. After the piston has traveled a short distance upwards into the cylinder the exhaust valve or port closes; shortly the intake valve or transfer port closes as well.
Compression: With both intake and exhaust closed the piston continues moving upwards compressing the charge and performing a work on it. As in the case of a 4-stroke engine, ignition starts just before the piston reaches TDC and the same consideration on the thermodynamics of the compression on the charge.
While a 4-stroke engine uses the piston as a positive displacement pump to accomplish scavenging taking 2 of the 4 strokes, a 2-stroke engine uses the last part of the power stroke and the first part of the compression stroke for combined intake and exhaust. The work required to displace the charge and exhaust gases comes from either the crankcase or a separate blower. For scavenging, expulsion of burned gas and entry of fresh mix, two main approaches are described: Loop scavenging, and Uniflow scavenging, SAE news published in the 2010s that 'Loop Scavenging' is better under any circumstance than Uniflow Scavenging.6
engine - wikipedia
An engine or motor is a machine designed to convert one form of energy into mechanical energy.12 Heat engines, including internal combustion engines and external combustion engines (such as steam engines), burn a fuel to create heat, which then creates a force. Electric motors convert electrical energy into mechanical motion; pneumatic motors use compressed air and others?such as clockwork motors in wind-up toys?use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create forces and eventually motion.
Vehicles from abroad
As is well known, very popular in Poland you are purchasing used cars. This involves a much lower cost, so it is no wonder that involved missing. Not less popular cars which were imported from abroad. In countries in Western Europe, many cars are exchanged after a short time of operation, and therefore that their condition is really good, are re-sold in Poland and other countries. Cars that have been used in Germany and France are often much less worn than the cars of the same vintage, which moved on Polish roads. That is why so much interest in such cars.