Skip Navigation Links Home / Clean Snowmobiles / Solutions / Engine / Two-Stroke Engine Principles

Solutions - Two-Stroke Engine Principles

Learn More About Two-Stroke Engines

Airborne Rider

These websites provide illustrated (and in some cases, animated) descriptions of the two-stroke engine:


Visit the websites of the following organizations to learn more about two-stroke engine technology:

  • Society of Automotive Engineers (SAE)

    The Society of Automotive Engineers bills itself as a one-stop resource for technical information and expertise used in designing, building, maintaining, and operating self-propelled vehicles for use on land or sea, in air or space. Nearly 80,000 engineers, business executives, educators, and students from more than 97 countries form SAE's network of membership who share information and exchange ideas for advancing the engineering of mobility systems. SAE says its technical committees write more new aerospace and automotive engineering standards than any other standards-writing organization in the world.

  • Southwest Research Institute (SwRI)

    The Automotive Products and Emissions Research Division is the largest of SwRI's 11 technical divisions. With a staff of about 600 employees, the division is internationally known for its fuels, lubricants, and emissions research activities. The division says its three departments work to uphold the longstanding tradition of quality and client response, started in 1947. The division helps clients get automotive products to the market and keep them there in response to regulation and competition. SwRI offers a broad range of services for product research, product development, and product qualification of automotive components and automotive fluids for on-road, off-road, rail, and water-borne transportation systems, as well as recreational vehicles and stationary power equipment.

  • Fuel Efficiency Automobile Test Data Center (FEAT)

    This site provides access to much of the remote sensing work emissions scientists at the University of Denver have been involved in since 1987. That work includes emissions data collected to date in 21 countries around the world and in more than 25 U.S. locations, including snowmobile emissions in Yellowstone National Park. Emissions data from snowmobiles are available at the website. Where available reports and links to pertinent publications are provided to support the databases.


The following books are good primers on two-stroke engines:

The Two-stroke Cycle Engine
John B. Haywood, Eran Sher
New York, N.Y.
Hardcover (June 1999)
Society of Automotive Engineer; ISBN: 0768003237

This is a comprehensive professional reference on the history, operating and performance characteristics, and the design of two-stroke cycle engines. It presents a coherent and up-to-date summary of information on this widely used and promising internal combustion engine concept. The book develops a fundamental understanding of the processes essential to the successful operation of the two-stroke cycle engine, and describes and evaluates the various types of models that have been developed to predict aspects of two-stroke engine operation. It reviews and explains the experimental methods that are used in two-stroke engine development and testing.

Design and Simulation of Two-Stroke Engines
By Gordon P. Blair
February 1996
647 Pages

This classic textbook discusses principles of automotive design specific to two-stroke engines. The book includes new theory the author has developed that has not been published before, particularly in relation to two-stroke engines, including: unsteady gas flow in engine ducting; scavenging flow within the cylinder; two-zone combustion to compute exhaust emissions; computation of intake and exhaust sound pressure levels; discharge coefficients or ports and valves.

Papers and Proceedings

The most comprehensive collection of scientific papers on small engines, including proceedings from technical conferences and workshops, can be found at the Society of Automotive Engineers website.

According to the Southwest Research Institute, two-stroke engines, with their small size and mechanical simplicity, provide unique benefits to engine designers, manufacturers, and users. Although two-stroke engines have been gradually abandoned for automotive use because of seemingly insurmountable emissions problems, new technology such as cost-effective in-cylinder fuel injection may lead to their resurgence.