The small 2-stroke engine Subtitle - Specific features and fields of application

The 2-stroke engine was invented in 1881 by the Englishman Dugald Clerk. The more modern version of this type of engine, known as the "crankcase pump", was designed ten years later by another Englishman, Joseph Day.

Up to now, the 2-stroke engine has been used for applications that benefit from its higher specific power than the 4-stroke engine.

This article is dedicated to the field of lightweight 2-stroke engines. These are applications requiring compact, light, spark-ignition engines (using gasoline-type fuels): from the smallest model engines (from 2 cm ³ displacement), through to small generators, portable tools (chainsaws, brushcutters, etc.), 2 and 3-wheelers, snow scooters and marine outboard motors (which can reach automobile-sized displacements).

During the 1990s, a new generation of 2-stroke direct-injection petrol engines was developed, gradually meeting growing environmental demands for reduced pollutant emissions. Significant associated advances in efficiency also resulted.

In 2021, the new-generation light 2-stroke engine will still be present in markets where its advantages over its 4-stroke competitor are undeniable, such as portable tools, snow scooters and tactical drones. It is also mainly present at the other end of the heat engine range, that of heavy-duty engines and in particular large marine 2-stroke engines, which is not covered in this article and is the subject of complementary articles "Heavy-duty 2-stroke engine – Application areas and specific structural features". [BM 2 653] and "Heavy 2-stroke engine – Specific characteristics of auxiliary systems [BM 2 654] .

A glossary and table of acronyms are provided at the end of the article.