page_title: Two-stroke engine
section_title: Applications
hierarchical_section_title: Two-stroke engine / Applications
caption_attribution_description: Polski: Saab 96 Sport
context_page_description: A two-stroke engine is a type of internal combustion engine that completes a power cycle with two strokes of the piston during only one crankshaft revolution. This is in contrast to a "four-stroke engine", which requires four strokes of the piston to complete a power cycle during two crankshaft revolutions. In a two-stroke engine, the end of the combustion stroke and the beginning of the compression stroke happen simultaneously, with the intake and exhaust functions occurring at the same time.
  Two-stroke engines often have a high power-to-weight ratio, power being available in a narrow range of rotational speeds called the "power band". Compared to four-stroke engines, two-stroke engines have a greatly reduced number of moving parts.
context_section_description: Two-stroke petrol engines are preferred when mechanical simplicity, light weight, and high power-to-weight ratio are design priorities.  With the traditional lubrication technique of mixing oil into the fuel, they also have the advantage of working in any orientation, as the oil reservoir is not dependent on gravity; this is an essential property for hand-held power tools such as chainsaws.
  A number of mainstream automobile manufacturers have used two-stroke engines in the past, including the Swedish Saab and German manufacturers DKW, Auto-Union, VEB Sachsenring Automobilwerke Zwickau, VEB Automobilwerk Eisenach, and VEB Fahrzeug- und Jagdwaffenwerk „Ernst Thälmann. The Japanese manufacturers Suzuki and Subaru did the same in the 1970s. Production of two-stroke cars ended in the 1980s in the West, due to increasingly stringent regulation of air pollution. Eastern Bloc countries continued until around 1991, with the Trabant and Wartburg in East Germany.  Two-stroke engines are still found in a variety of small propulsion applications, such as outboard motors, high-performance, small-capacity motorcycles, mopeds, dirt bikes, underbones, scooters, tuk-tuks, snowmobiles, karts, ultralight airplanes, and model airplanes and other model vehicles.  They are also common in power tools used outdoors, such as lawn mowers, chainsaws, and weed-wackers.
  With direct fuel injection and a sump-based lubrication system, a two-stroke engine produces air pollution no worse than a four-stroke, and it can achieve higher thermodynamic efficiency.  Therefore, the cycle has historically also been used in large diesel engines, mostly large industrial and marine engines, as well as some trucks and heavy machinery.  Several experimental designs  are intended for automobile use; for instance,  Lotus of Norfolk, UK, had in 2008 a prototype direct-injection, two-stroke engine intended for alcohol fuels called the Omnivore, which it is demonstrating in a version of the Exige.
caption: 1966 Saab Sport
exif: {"Image ImageWidth": "4608", "Image ImageLength": "3456", "Image BitsPerSample": "[8, 8, 8]", "Image PhotometricInterpretation": "2", "Image Make": "NIKON", "Image Model": "COOLPIX P510", "Image Orientation": "Horizontal (normal)", "Image SamplesPerPixel": "3", "Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS6 (Windows)", "Image DateTime": "2015:01:27 13:56:34", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "300", "GPS GPSVersionID": "[50, 51, 48, 48]", "GPS GPSLatitudeRef": "", "GPS GPSLatitude": "[0/0, 0/0, 0/0]", "GPS GPSLongitudeRef": "", "GPS GPSLongitude": "[0/0, 0/0, 0/0]", "GPS GPSAltitudeRef": "0", "GPS GPSAltitude": "0/0", "GPS GPSTimeStamp": "[0/0, 0/0, 0/0]", "GPS GPSSatellites": "", "GPS GPSImgDirectionRef": "", "GPS GPSImgDirection": "0/0", "GPS GPSMapDatum": "", "GPS GPSDate": "", "Image GPSInfo": "1024", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1390", "Thumbnail JPEGInterchangeFormatLength": "7954", "EXIF ExposureTime": "1/15", "EXIF FNumber": "3", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "400", "EXIF SensitivityType": "Standard Output Sensitivity", "EXIF ExifVersion": "0230", "EXIF DateTimeOriginal": "2014:12:07 14:00:59", "EXIF DateTimeDigitized": "2014:12:07 14:00:59", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "4", "EXIF ShutterSpeedValue": "3906891/1000000", "EXIF ApertureValue": "126797/40000", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "16/5", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "43/10", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "4608", "EXIF ExifImageLength": "3456", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "992", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "0", "EXIF FocalLengthIn35mmFilm": "24", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "High gain up", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal", "EXIF SubjectDistanceRange": "0"}