Editing Diesel engine (section)

==Applications==
The characteristics of diesel have different advantages for different applications.

===Passenger cars===
{{See also|History of the diesel car}}
Diesel engines have long been popular in bigger cars and have been used in smaller cars such as [[supermini]]s in Europe since the 1980s. They were popular in larger cars earlier, as the weight and cost penalties were less noticeable.<ref name="AG125">{{Cite journal |last=Pirotte |first=Marcel |date=1984-07-05 |title=Gedetailleerde Test: Citroën BX19 TRD |trans-title=Detailed Test |journal=De AutoGids |language=nl-be |location=Brussels, Belgium |volume=5 |page=6 |ref=AG125 |number=125}}</ref> Smooth operation as well as high low-end torque are deemed important for passenger cars and small commercial vehicles. The introduction of electronically controlled fuel injection significantly improved the smooth torque generation, and starting in the early 1990s, car manufacturers began offering their high-end luxury vehicles with diesel engines. Passenger car diesel engines usually have between three and twelve cylinders, and a displacement ranging from 0.8 to 6.0 litres. Modern powerplants are usually turbocharged and have direct injection.<ref name="Reif_2014_11" />

Diesel engines do not suffer from intake-air throttling, resulting in very low fuel consumption especially at low partial load<ref name="Reif_2014_23" /> (for instance: driving at city speeds). One fifth of all passenger cars worldwide have diesel engines, with many of them being in Europe, where approximately 47% of all passenger cars are diesel-powered.<ref name="Tschöke_2018_1000" /> [[Daimler-Benz]] in conjunction with [[Robert Bosch GmbH]] produced diesel-powered passenger cars starting in 1936.<ref name="Tschöke_2018_10" /> The popularity of diesel-powered passenger cars in markets such as India, South Korea and Japan is increasing (as of 2018).<ref name="Tschöke_2018_981" />

===Commercial vehicles and lorries===
{{Image frame|width=220|content=
{{Graph:Chart|width=150|height=200|xAxisTitle=Engine model|yAxisTitle=Lifespan (km)|yAxisFormat=s|type=rect |yGrid= |xAxisAngle=-40
|x=OM 355,OM 400, OM 500, OM 470|y=500000,750000,1000000,1200000}}
|caption=Lifespan of Mercedes-Benz diesel engines<ref name="Merker_2014_264" />|link=|align=right}}

In 1893, Rudolf Diesel suggested that the diesel engine could possibly power "wagons" (lorries).<ref name="Diesel_1893_91" /> The first lorries with diesel engines were brought to market in 1924.<ref name="Tschöke_2018_10" />

Modern diesel engines for lorries have to be both extremely reliable and very fuel efficient. Common-rail direct injection, turbocharging and four valves per cylinder are standard. Displacements range from 4.5 to 15.5 litres, with [[Power-to-weight ratio|power-to-mass ratios]] of 2.5–3.5&nbsp;kg·kW<sup>−1</sup> for heavy duty and 2.0–3.0&nbsp;kg·kW<sup>−1</sup> for medium duty engines. [[V engine|V6 and V8 engines]] used to be common, due to the relatively low engine mass the V configuration provides. Recently, the V configuration has been abandoned in favour of straight engines. These engines are usually straight-6 for heavy and medium duties and straight-4 for medium duty. Their [[undersquare]] design causes lower overall piston speeds which results in increased lifespan of up to {{convert| 1200000| km|mi}}.<ref name="Merker_2014_48" /> Compared with 1970s diesel engines, the expected lifespan of modern lorry diesel engines has more than doubled.<ref name="Merker_2014_264" />

===Railroad rolling stock===
Diesel engines for locomotives are built for continuous operation between refuelings and may need to be designed to use poor quality fuel in some circumstances.<ref name="Reif_2014_12" /> Some locomotives use two-stroke diesel engines.<ref name="Merker_2014_284" /> Diesel engines have replaced [[Steam locomotive|steam engine]]s on all non-electrified railroads in the world. The first [[diesel locomotive]]s appeared in 1913,<ref name="Tschöke_2018_10" /> and [[diesel multiple units]] soon after. Nearly all modern diesel locomotives are more correctly known as [[diesel–electric locomotive]]s because they use an electric transmission: the diesel engine drives an electric generator which powers electric traction motors.<ref name="vB_2017_1289" /> While [[electric locomotive]]s have replaced the diesel locomotive for passenger services in many areas diesel traction is widely used for cargo-hauling [[freight train]]s and on tracks where electrification is not economically viable.

In the 1940s, road vehicle diesel engines with power outputs of {{convert|150|-|200|PS|kW hp}} were considered reasonable for DMUs. Commonly, regular truck powerplants were used. The height of these engines had to be less than {{convert|1|m}} to allow underfloor installation. Usually, the engine was mated with a pneumatically operated mechanical gearbox, due to the low size, mass, and production costs of this design. Some DMUs used hydraulic torque converters instead. Diesel–electric transmission was not suitable for such small engines.<ref name="Kremser_1942_22" /> In the 1930s, the [[Deutsche Reichsbahn]] standardised its first DMU engine. It was a {{convert|30.3|litre|cuin}}, 12-cylinder boxer unit, producing {{convert|275|PS|kW hp}}. Several German manufacturers produced engines according to this standard.<ref name="Kremser_1942_23" />

===Watercraft===
[[File:8 cylinder Burmeister & Wain Diesel engine for MS Glenapp 1920.png|thumb|One of the eight-cylinder 3200 I.H.P. Harland and Wolff – Burmeister & Wain diesel engines installed in the motorship ''Glenapp''. This was the highest powered diesel engine yet (1920) installed in a ship. Note man standing lower right for size comparison.]]
[[File:InleHandCrank.webm|thumb|right|Hand-cranking a boat diesel motor in [[Inle Lake]] ([[Myanmar]])]]
The requirements for marine diesel engines vary, depending on the application. For military use and medium-size boats, medium-speed four-stroke diesel engines are most suitable. These engines usually have up to 24 cylinders and come with power outputs in the one-digit Megawatt region.<ref name="Reif_2014_12" /> Small boats may use lorry diesel engines. Large ships use extremely efficient, low-speed two-stroke diesel engines. They can reach efficiencies of up to 55%. Unlike most regular diesel engines, two-stroke watercraft engines use highly viscous [[fuel oil]].<ref name="Reif_2014_13" /> Submarines are usually diesel–electric.<ref name="vB_2017_1289" />

The first diesel engines for ships were made by A. B. Diesels Motorer Stockholm in 1903. These engines were three-cylinder units of 120&nbsp;PS (88&nbsp;kW) and four-cylinder units of 180&nbsp;PS (132&nbsp;kW) and used for Russian ships. In World War I, especially submarine diesel engine development advanced quickly. By the end of the War, double acting piston two-stroke engines with up to 12,200&nbsp;PS (9&nbsp;MW) had been made for marine use.<ref name="Mau_1984_9_11" />

===Aviation===
{{Main|Aircraft diesel engine}}

====Early====
Diesel engines had been used in aircraft before World War II, for instance, in the rigid airship ''[[LZ 129 Hindenburg]],'' which was powered by four [[Daimler-Benz DB 602]] diesel engines,<ref>Kyrill von Gersdorff, Kurt Grasmann: ''Flugmotoren und Strahltriebwerke: Entwicklungsgeschichte der deutschen Luftfahrtantriebe von den Anfängen bis zu den internationalen Gemeinschaftsentwicklungen'', Bernard & Graefe, 1985, {{ISBN|9783763752836}}, p. 14</ref> or in several Junkers aircraft, which had [[Junkers Jumo 205|Jumo 205]] engines installed.<ref name="Reif_2012_103" />

In 1929, in the United States, the [[Packard Motor Company]] developed America's first aircraft diesel engine, the [[Packard DR-980]]—an air-cooled, 9-cylinder [[radial engine]]. They installed it in various aircraft of the era—some of which  were used in record-breaking distance or endurance flights,<ref name="flies_700_miles_1929_05_15_nytimes_com">[https://www.nytimes.com/1929/05/15/archives/flies-700-miles-fuel-cost-468-dieselmotored-packard-plane-goes-from.html "FLIES 700 MILES; FUEL COST $4.68; Diesel-Motored Packard Plane Goes From Michigan to Langley Field in Under Seven Hours. ENGINE HAS NINE CYLINDERS Oil Burner Is Exhibited Before Aviation Leaders, Met for Conference. Woolson Reports on Flight. Packard Motor Stocks Rise,"] May 15, 1929, ''[[New York Times]],'' retrieved December 5, 2022</ref><ref name="packard_2019_05_24_dieselworldmag_com">[https://www.dieselworldmag.com/diesel-engines/first-in-flight/ "The Packard DR-980 Radial Aircraft Diesel"] "First in Flight," "Diesel Engines," May 24, 2019, ''Diesel World'' magazine, retrieved December 5, 2022</ref><ref name="packard_diesel_buhl_earlyaviators_com">[https://www.earlyaviators.com/pimage26.htm "Packard-Diesel Powered Buhl Air Sedan, 1930"] (reproductions of early media articles and photos, with added information), ''Early Birds of Aviation,'' retrieved December 5, 2022</ref><ref name=enginehistory>[http://www.enginehistory.org/Diesels/CH1.pdf Aircraft Engine Historical Society – Diesels] {{webarchive|url=https://web.archive.org/web/20120212213152/http://www.enginehistory.org/Diesels/CH1.pdf |date=2012-02-12 }} Retrieved: 30 January 2009</ref> and in the first successful demonstration of ground-to-air radiophone communications (voice radio having been previously unintelligible in aircraft equipped with spark-ignition engines, due to [[electromagnetic interference]]).<ref name="packard_2019_05_24_dieselworldmag_com" /><ref name="packard_diesel_buhl_earlyaviators_com" /> Additional advantages cited, at the time, included a lower risk of post-crash fire, and superior performance at high altitudes.<ref name="packard_2019_05_24_dieselworldmag_com" />

On March 6, 1930, the engine received an [[Type Certificate|Approved Type Certificate]]—first ever for an aircraft diesel engine—from the [[U.S. Department of Commerce]].<ref name="diesel_aviation_engines_1940_enginehistory_org">Wilkinson, Paul H.: [https://www.enginehistory.org/Piston/Diesels/diesels.shtml "Diesel Aviation Engines,"] 1940, reproduced at Aviation Engine Historical Society, retrieved December 5, 2022</ref> However, noxious exhaust fumes, cold-start and vibration problems, engine structural failures, the death of its developer, and the industrial economic contraction of the [[Great Depression]], combined to kill the program.<ref name="packard_2019_05_24_dieselworldmag_com" />

====Modern====
From then, until the late 1970s, there had not been many applications of the diesel engine in aircraft. In 1978, [[Piper Cherokee]] co-designer Karl H. Bergey argued that "the likelihood of a general aviation diesel in the near future is remote."<ref>Karl H. Bergey: ''[https://books.google.com/books?id=av85AQAAMAAJ Assessment of New Technology for General Aviation Aircraft]'', Report for U.S. Department of Transportation, September 1978, p. 19</ref>

However, with the [[1970s energy crisis]] and [[environmental movement]], and resulting pressures for greater fuel economy, reduced carbon and lead in the atmosphere, and other issues, there was a resurgence of interest in diesel engines for aircraft. High-compression piston aircraft engines that run on aviation gasoline ("[[avgas]]") generally require the addition of toxic [[Tetraethyl lead]] to avgas, to avoid engine [[Engine knocking|pre-ignition and detonation]]; but diesel engines do not require leaded fuel. Also, [[biodiesel]] can, theoretically, provide a net reduction in atmospheric carbon compared to avgas. For these reasons, the [[general aviation]] community has begun to fear the possible banning or discontinuance of leaded avgas.<ref name="inside_2018_08_01_flyingmag_com" /><ref name="congressman_2012_10_24_generalaviationnews">Wood, Janice (editor): [https://generalaviationnews.com/2012/10/24/congressman-calls-on-faa-to-expand-use-of-unleaded-fuel/ Congressman urges FAA to expand use of existing unleaded fuel,"] October 24, 2012, ''General Aviation News,'' retrieved December 6, 2022</ref><ref name="hanke_2006_07_21_g_a_news">[https://www.linkedin.com/in/kurt-hanke-6bb24ab Hanke, Kurt F., engineer] ([https://www.turbocraft.com/ Turbocraft, Inc.]), [https://generalaviationnews.com/2006/07/21/diesels-are-the-way-for-ga-to-go/ "Diesels are the Way for GA to Go,"] July 21, 2006, ''Ge eral Aviation News,'' retrieved December 6, 2022</ref><ref name="biodiesel_basics_2003_energy_gov">{{cite journal|title=Biodiesel – Just the Basics|version=Final|year=2003|publisher=United States Department of Energy|url=http://www.eere.energy.gov/vehiclesandfuels/pdfs/basics/jtb_biodiesel.pdf|access-date=2007-08-24|url-status=dead|archive-url=https://web.archive.org/web/20070918122719/http://www1.eere.energy.gov/vehiclesandfuels/pdfs/basics/jtb_biodiesel.pdf|archive-date=2007-09-18}}</ref>

Additionally, avgas is a specialty fuel in very low (and declining) demand, compared to other fuels, and its makers are susceptible to costly aviation-crash lawsuits, reducing refiners' interest in producing it.  Outside the United States, avgas has already become increasingly difficult to find at airports (and generally), than less-expensive, diesel-compatible fuels like Jet-A and other [[jet fuel]]s.<ref name="inside_2018_08_01_flyingmag_com" /><ref name="congressman_2012_10_24_generalaviationnews" /><ref name="hanke_2006_07_21_g_a_news" /><ref name="biodiesel_basics_2003_energy_gov" />

By the late 1990s / early 2000s, diesel engines were beginning to appear in light aircraft.  Most notably, [[Thielert|Frank Thielert and his Austrian engine enterprise]], began developing diesel engines to replace the {{convert|100|hp|kW}} - {{convert|350|hp|kW}} gasoline/piston engines in common light aircraft use.<ref name="powerplant_ch7_phak_faa_gov">[https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/09_phak_ch7.pdf "Powerplant"], in Chapter 7: "Aircraft Systems," ''Pilot's Handbook of Aeronautical Knowledge,'' [[Federal Aviation Administration]], retrieved December 5, 2022</ref> First successful application of the Theilerts to production aircraft was in the [[Diamond DA42 Twin Star]] light twin, which exhibited exceptional fuel efficiency surpassing anything in its class,<ref name="inside_2018_08_01_flyingmag_com" /><ref name="diamond_2020_12_30_avweb_com" /><ref name="diamond_da42_2004_05_12_flightglobal_com">Collins, Peter: [https://www.flightglobal.com/flight-test-diamond-aircraft-da42-sparkling-performer/55396.article "FLIGHT TEST: Diamond Aircraft DA42 - Sparkling performer,"] July 12, 2004, ''[[FlightGLobal]]'' retrieved December 5, 2022</ref> and its single-seat predecessor, the [[Diamond DA40 Diamond Star]].<ref name="inside_2018_08_01_flyingmag_com" /><ref name="diamond_2020_12_30_avweb_com" /><ref name="powerplant_ch7_phak_faa_gov" />

In subsequent years, several other companies have developed aircraft diesel engines, or have begun to<ref name="powerplant_ch7_phak_faa_gov" />—most notably [[Continental Aerospace Technologies]] which, by 2018, was reporting it had sold over 5,000 such engines worldwide.<ref name="inside_2018_08_01_flyingmag_com" /><ref name="diamond_2020_12_30_avweb_com" /><ref name="certified_jet_a_engines_continental_aero">[https://www.continental.aero/diesel/diesel-engines.aspx "Certified Jet-A Engines,"], [[Continental Aerospace Technologies]], retrieved December 5, 2022</ref>

The United States' [[Federal Aviation Administration]] has reported that "by 2007, various jet-fueled piston aircraft had logged well over 600,000 hours of service".<ref name="powerplant_ch7_phak_faa_gov" /> In early 2019, [[Aircraft Owners and Pilots Association|AOPA]] reported that a diesel engine model for general aviation aircraft is "approaching the finish line."<ref name="eps_update_2019_01_23_aopa_org">[https://www.aopa.org/news-and-media/all-news/2019/january/23/eps-gives-certification-update-on-diesel-engine ''EPS gives certification update on diesel engine,''], January 23, 2019, [[Aircraft Owners and Pilots Association|AOPA]]. Retrieved November 1, 2019.</ref> By late 2022, Continental was reporting that its "Jet-A" fueled engines had exceeded "2,000... in operation today," with over "9 million hours," and were being "specified by major OEMs" for [[Cessna Aircraft|Cessna]], [[Piper Aircraft|Piper]],  [[Diamond Aircraft|Diamond]], [[Mooney Aircraft|Mooney]], [[Tecnam Aircraft|Tecnam]], [[Glasair]] and [[Avions Pierre Robin|Robin]] aircraft.<ref name="certified_jet_a_engines_continental_aero" />

In recent years (2016), diesel engines have also found use in unmanned aircraft (UAV), due to their reliability, durability, and low fuel consumption.<ref name="knock_criteria_2017_meininger_doi_org">Rik D Meininger et al.: "Knock criteria for aviation diesel engines", ''International Journal of Engine Research,'' Vol 18, Issue 7, 2017, [https://doi.org/10.1177/1468087416669882 doi/10.1177]</ref><ref name="Arnews2005">{{cite news |title=Army awards 'Warrior' long-range UAV contract |date=2005-08-05 |publisher=Army News Service |url=http://www4.army.mil/news/article.php?story=7722 |url-status=dead |archive-url=https://web.archive.org/web/20070102153829/http://www4.army.mil/news/article.php?story=7722 |archive-date=2 January 2007  }}</ref><ref name="defenseupdate2006">{{cite news |title= ERMP Extended-Range Multi-Purpose UAV |publisher= Defense Update |date= 2006-11-01 |url= http://www.defense-update.com/products/e/ermpUAV.htm |access-date= 11 May 2007 |archive-url= https://web.archive.org/web/20080513125340/http://www.defense-update.com/products/e/ermpUAV.htm |archive-date= 13 May 2008 |url-status= dead |df= dmy-all }}</ref>

===Non-road diesel engines===
[[File:Porsche F 218.jpg|thumb|Air-cooled diesel engine of a 1959 Porsche 218]]

[[Non-road engine|Non-road diesel engines]] are commonly used for [[construction equipment]] and [[agricultural machinery]]. Fuel efficiency, reliability and ease of maintenance are very important for such engines, whilst high power output and quiet operation are negligible. Therefore, mechanically controlled fuel injection and air-cooling are still very common. The common power outputs of non-road diesel engines vary a lot, with the smallest units starting at 3&nbsp;kW, and the most powerful engines being heavy duty lorry engines.<ref name="Reif_2014_12" />

===Stationary diesel engines===
[[File:The National Archives UK - CO 1069-182-9.jpg|thumb|Three English Electric 7SRL diesel-alternator sets being installed at the Saateni Power Station; [[Zanzibar]], 1955]]

Stationary diesel engines are commonly used for electricity generation, but also for powering refrigerator compressors, or other types of compressors or pumps. Usually, these engines either run continuously with partial load, or intermittently with full load. Stationary diesel engines powering electric generators that put out an alternating current, usually operate with alternating load, but fixed rotational frequency. This is due to the mains' fixed frequency of either 50&nbsp;Hz (Europe), or 60&nbsp;Hz (United States). The engine's [[crankshaft]] rotational frequency is chosen so that the mains' frequency is a multiple of it. For practical reasons, this results in [[crankshaft]] rotational frequencies of either 25&nbsp;Hz (1500 per minute) or 30&nbsp;Hz (1800 per minute).<ref name="Tschöke_2018_1066" />

=== Diesel engines with a flexible crankshaft ===
Diesel engines with a flexible [[crankshaft]] refer to internal combustion engines where the [[crankshaft]] exhibits a degree of elasticity due to operational stresses, manufacturing tolerances, and material properties. Unlike a perfectly rigid [[crankshaft]], a flexible one undergoes dynamic deformations due to cyclic combustion forces, inertial loads, and lubrication effects, which can lead to eccentric motion and vibrational displacement. This flexibility can impact engine performance by influencing bearing loads, lubrication film distribution, and mechanical wear, potentially reducing efficiency and lifespan. Advanced modeling techniques, such as Finite Element Analysis (FEA) and Multi-Body Dynamics (MBD), are used to predict and mitigate these effects, enabling better engine design, improved fuel efficiency, and enhanced durability. The flexibility of a crankshaft decreases the mass flow rate of air that goes into cylinders, resulting in an unfavorable higher rate of exhaust emissions like CO.<ref>{{Cite journal |last1=Elmoselhy |first1=Salah A. M. |last2=Faris |first2=Waleed F. |last3=Rakha |first3=Hesham A. |date=2021-02-26 |title=Validated Analytical Modeling of Diesel Engines Intake Manifold with a Flexible Crankshaft |journal=Energies |language=en |volume=14 |issue=5 |pages=1287 |doi=10.3390/en14051287 |doi-access=free |issn=1996-1073|hdl=10919/102459 |hdl-access=free }}</ref>