page_title: Four-stroke engine
section_title: Diesel cycle
hierarchical_section_title: Four-stroke engine / History / Diesel cycle
caption_attribution_description: The #1 Audi Sport Team Joest Audi R15 TDI approaching Arnage Corner at the 2009 24 Hours of Le Mans.
context_page_description: A four-stroke engine is an internal combustion engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either direction. The four separate strokes are termed:
  Intake: Also known as induction or suction. This stroke of the piston begins at top dead center and ends at bottom dead center. In this stroke the intake valve must be in the open position while the piston pulls an air-fuel mixture into the cylinder by producing vacuum pressure into the cylinder through its downward motion. The piston is moving down as air is being sucked in by the downward motion against the piston.
  Compression: This stroke begins at B.D.C, or just at the end of the suction stroke, and ends at T.D.C. In this stroke the piston compresses the air-fuel mixture in preparation for ignition during the power stroke. Both the intake and exhaust valves are closed during this stage.
  Combustion: Also known as power or ignition. This is the start of the second revolution of the four stroke cycle. At this point the crankshaft has completed a full 360 degree revolution.
context_section_description: The diesel engine is a technical refinement of the 1876 Otto-cycle engine. Where Otto had realized in 1861 that the efficiency of the engine could be increased by first compressing the fuel mixture prior to its ignition, Rudolf Diesel wanted to develop a more efficient type of engine that could run on much heavier fuel. The Lenoir, Otto Atmospheric, and Otto Compression engines (both 1861 and 1876) were designed to run on Illuminating Gas (coal gas). With the same motivation as Otto, Diesel wanted to create an engine that would give small industrial companies their own power source to enable them to compete against larger companies, and like Otto, to get away from the requirement to be tied to a municipal fuel supply. Like Otto, it took more than a decade to produce the high-compression engine that could self-ignite fuel sprayed into the cylinder. Diesel used an air spray combined with fuel in his first engine.
  During initial development, one of the engines burst, nearly killing Diesel. He persisted, and finally created a successful engine in 1893. The high-compression engine, which ignites its fuel by the heat of compression, is now called the diesel engine, whether a four-stroke or two-stroke design.
  The four-stroke diesel engine has been used in the majority of heavy-duty applications for many decades. It uses a heavy fuel containing more energy and requiring less refinement to produce. The most efficient Otto-cycle engines run near 30% thermal efficiency.
caption: Audi Diesel R15 at Le Mans
exif: {"Image Make": "Canon", "Image Model": "Canon PowerShot G6", "Image Orientation": "Horizontal (normal)", "Image XResolution": "180", "Image YResolution": "180", "Image ResolutionUnit": "Pixels/Inch", "Image DateTime": "2009:06:13 19:01:12", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "196", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "180", "Thumbnail YResolution": "180", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "2548", "Thumbnail JPEGInterchangeFormatLength": "4624", "EXIF ExposureTime": "1/200", "EXIF FNumber": "5/2", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2009:06:13 19:01:12", "EXIF DateTimeDigitized": "2009:06:13 19:01:12", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "3", "EXIF ShutterSpeedValue": "245/32", "EXIF ApertureValue": "85/32", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "85/32", "EXIF MeteringMode": "CenterWeightedAverage", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "253/16", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "3072", "EXIF ExifImageLength": "2304", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "Interoperability RelatedImageWidth": "3072", "Interoperability RelatedImageLength": "2304", "EXIF InteroperabilityOffset": "1882", "EXIF FocalPlaneXResolution": "768000/71", "EXIF FocalPlaneYResolution": "768000/71", "EXIF FocalPlaneResolutionUnit": "2", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF SceneCaptureType": "Standard"}