{{Short description|Diesel engine with a turbocharger}} {{Use dmy dates|date=March 2020}} {{Use British English|date=March 2020}} {{multiple image | align = right | direction = vertical | width = 220 | image1 = LR19JTurbo.JPG | caption1 = 1990 [[Land Rover engines#Diesel Turbo (Engine Code 19J)|Land Rover 19J]] engine (turbocharger is towards the top-right corner of image) | image2 = | caption2 = 1983–1988 [[BMW M21]] engine (turbocharger is near the bottom of the image) }}
The term '''turbo-diesel''', also written as '''turbodiesel''' and '''turbo diesel''', refers to any [[diesel engine]] equipped with a [[turbocharger]]. As with other engine types, turbocharging a diesel engine can significantly increase its efficiency and power output, especially when used in combination with an [[intercooler]].<ref>{{Citation |last1=Zinner |first1=Karl |first2=Helmut |last2=Pucher |year=2012 |title=Aufladung von Verbrennungsmotoren |series= |edition=4|volume= |publisher=Springer |location=Berlin/Heidelberg |isbn=978-3-642-28989-7 |language=de |pages=7–8; 106}}</ref>
Turbocharging of diesel engines began in the 1920s with large marine and stationary engines. Trucks became available with turbo-diesel engines in the mid-1950s, followed by passenger cars in the late 1970s. Since the 1990s, the compression ratio of turbo-diesel engines has been dropping.
== Principle == Diesel engines are typically well suited to turbocharging due to two factors: * A "lean" [[air–fuel ratio]], caused when the turbocharger supplies excess air into the engine, is not a problem for diesel engines, because the torque control is dependent on the mass of fuel that is injected into the combustion chamber (i.e. air-fuel ratio), rather than the quantity of the air-fuel mixture.<ref>{{cite book |last1=Pischinger |first1=Stefan |last2=Seiffert |first2=Ulrich |title=Vieweg Handbuch Kraftfahrzeugtechnik |date=2016 |isbn=978-3-658-09528-4 |url=https://books.google.com/books?id=4nsSDQAAQBAJ |pages=348 |publisher=Springer |language= de |edition=8}}</ref> * The additional quantity of air in the cylinder due to turbocharging effectively increases the compression ratio, which, in a petrol engine, can cause [[pre-ignition]] and high [[exhaust gas temperature]]s. However, in a diesel engine, fuel is not present in the combustion chamber during the [[compression stroke]], since it is only added to the combustion chamber shortly before the piston reaches top dead center. Thus, no pre-ignition can occur.<ref>{{cite book |last1=Reif |first1=Konrad |title=Grundlagen Fahrzeug- und Motorentechnik |date=2017 |language= de |url=https://books.google.com/books?id=TdgEMQAACAAJ |isbn=978-3-658-12635-3 |pages=16 |publisher=Springer }}</ref>
As per turbocharged petrol engines, an [[intercooler]] can be used to cool the intake air and therefore increase its density.<ref>{{cite book |last1=Tschöke |first1=Helmut |last2=Mollenhauer |first2=Klaus |last3=Maier |first3=Rudolf |title=Handbuch Dieselmotoren |date=2018 |isbn=978-3-658-07696-2 |url=https://books.google.com/books?id=F3IvjgEACAAJ |pages=702 |publisher=Springer |language= de |edition=8}}</ref>
==History== {{see also|Turbocharger#History}} The turbocharger was invented in the early 20th century by [[Alfred Büchi]], a Swiss engineer and the head of diesel engine research at the [[Sulzer (manufacturer)|Gebrüder Sulzer]] engine manufacturing company. The turbocharger was originally intended to be used on diesel engines, since Büchi's patent of 1905 noted the efficiency improvements that a turbocharger could bring to diesel engines.<ref>{{cite book |last1=Vann |first1=Peter |title=Porsche Turbo: The Full History |date=11 Jul 2004 |publisher=MotorBooks International}}</ref><ref>{{cite book |last1=Gresh |first1=M |last2=Newnes |first2=Theodore |title=Compressor Performance: Aerodynamics for the User |date=29 March 2001}}</ref><ref>{{cite journal |title=Diesel and gas turbine progress |journal=Diesel Engines, Inc. |date=1960 |volume=26}}</ref> However, the first production turbocharged engines to be manufactured did not occur until 1925, 10-cylinder turbo-diesel marine engines used by the German passenger ships ''Preussen'' and {{ship|German minelayer|Hansestadt Danzig||2}}.<ref>{{cite web |title=The turbocharger turns 100 years old this week |url=https://newatlas.com/go/4848/ |website=www.newatlas.com |access-date=29 September 2019 |language=en |date=18 November 2005}}</ref><ref>Doug Woodyard (ed.): ''Pounder's Marine Diesel Engines and Gas Turbines'', 9th edition, Butterworth-Heinemann, 2009, {{ISBN|9780080943619}}, p. 192</ref> The turbocharger increased the power output from {{cvt|1750|PS|kW|0}} to {{cvt|2500|PS|kW|0}}.<ref>{{Citation |last1=Zinner |first1=Karl |first2=Helmut |last2=Pucher |year=2012 |title=Aufladung von Verbrennungsmotoren |series= |edition=4|volume= |publisher=Springer |location=Berlin/Heidelberg |isbn=978-3-642-28989-7 |language=de |pages=20}}</ref> In 1925, Büchi invented sequential turbocharging, which according to Helmut Pucher (2012) marks the beginning of modern turbocharging technology.<ref>{{Citation |last1=Zinner |first1=Karl |first2=Helmut |last2=Pucher |year=2012 |title=Aufladung von Verbrennungsmotoren |series= |edition=4|volume= |publisher=Springer |location=Berlin/Heidelberg |isbn=978-3-642-28989-7 |language=de |pages=21}}</ref>
By the late 1920s, several manufacturers were producing large turbo-diesels for marine and stationary use, such as Sulzer Bros., MAN, Daimler-Benz, and Paxman.<ref>{{cite journal |journal=Shipbuilding & Marine Engineering International |date=1933 |volume=56 |publisher=Whitehall Press}}</ref><ref>{{cite journal |last1=Clarke |first1=Donald |last2=Dartford |first2=Mark |last3=Stuttman |first3=H.S. |title=How It Works |journal=The New Illustrated Science and Invention Encyclopedia |date=1994 |volume=6}}</ref> Subsequent improvements in technology made feasible the use of turbochargers on smaller engines that ran at higher engine speeds, so turbo-diesel locomotive engines began appearing in the late 1940s.<ref>Illustrated Encyclopedia of World Railway Locomotives, P. Ransome-Wallis, Courier Dover Publications, 9 Mar 2001</ref><ref>{{cite book |last1=Wilson |first1=Jeff |title=The Model Railroader's Guide to Diesel Locomotives |date=1 Dec 2009 |publisher=Kalmbach Publishing}}</ref> In 1951, MAN built the K6V 30/45 m.H.A., 1 MW<!-- six-cylinder engine with a 300 mm bore and 450 mm stroke, producing an effective pressure of 1.569 MPa at 400/min--> prototype engine, which had, for its time, an exceptionally low fuel consumption of just {{cvt|135.8|g/PSh|g/kWh|1}}, equivalent to an efficiency of 45.7 per cent.<ref>{{Citation |last1=Zinner |first1=Karl |first2=Helmut |last2=Pucher |year=2012 |title=Aufladung von Verbrennungsmotoren |series= |edition=4|volume= |publisher=Springer |location=Berlin/Heidelberg |isbn=978-3-642-28989-7 |language=de |pages=22}}</ref> This was possible because of the advanced turbocharger design, comprising a five-stage [[axial compressor]] combined with a nine-stage [[radial compressor]] and an intercooler.<ref>{{Citation |last1=Zinner |first1=Karl |first2=Helmut |last2=Pucher |year=2012 |title=Aufladung von Verbrennungsmotoren |series= |edition=4|volume= |publisher=Springer |location=Berlin/Heidelberg |isbn=978-3-642-28989-7 |language=de |pages=22}}</ref>
Use of turbo-diesel engines in road-going vehicles began with trucks in the early 1950s. The prototype MAN MK26 truck was unveiled in 1951,<ref>{{cite web |title=150 Years Rudolf Diesel - MAN History |url=http://www.mantruckandbus.com/man/msites/150_Jahre_Diesel/index_en.html |website=www.mantruckandbus.com |url-status=dead |archive-url=https://web.archive.org/web/20120702114713/www.mantruckandbus.com/man/msites/150_Jahre_Diesel/index_en.html |archive-date=2 July 2012}}</ref> followed by the production model MAN 750TL1 turbo-diesel in 1954.<ref>{{cite book |last1=Tipler |first1=John |title=Trucks |date=1 Aug 1999}}</ref> The [[Volvo Titan|Volvo Titan Turbo]] truck was also introduced in 1954.<ref>{{cite web |title=1950s - Volvo Trucks |url=http://www.volvotrucks.com/en-en/about-us/history/1950s.html |website=www.volvotrucks.com |access-date=29 September 2019 |language=en |archive-date=27 January 2017 |archive-url=https://web.archive.org/web/20170127035121/http://www.volvotrucks.com/en-en/about-us/history/1950s.html |url-status=dead }}</ref> By the late 1960s, demand for increasingly powerful truck engines led to turbo-diesels being produced by [[Cummins]], [[Detroit Diesel]], [[Scania AB]], and [[Caterpillar Inc]].
In 1952, the Cummins Diesel Special became the first turbocharged car to compete at the [[Indianapolis 500]] motor race and qualified on pole position.<ref>{{cite web |title=High Tech is Getting the Cummins Diesel Special Back to Indianapolis |url=https://www.cummins.com/news/2019/05/09/high-tech-getting-cummins-diesel-special-back-indianapolis |website=www.cummins.com |date=9 May 2019 |access-date=29 September 2019 |language=en}}</ref> The car was powered by a {{convert|6.6|L|cuin|0|abbr=on}} [[inline-six]] engine producing {{convert|380|hp|kW|0|abbr=on|order=flip}}.<ref>{{cite web |title=Kevin Triplett's Racing History |url=https://triplettracehistory.blogspot.com/2016/01/the-1931-cummins-diesel-photo-by-author.html |website=www.triplettracehistory.blogspot.com |access-date=29 September 2019 |language=en |date=1 August 2008}}</ref><ref>{{cite web |title=Cummins at the Indy 500 - Diesel Alley |url=http://www.trucktrend.com/cool-trucks/0808dp-cummins-diesel-race-car/ |website=www.trucktrend.com |date=August 2008 |access-date=29 September 2019}}</ref>
Research into smaller turbo-diesel engines for passenger cars was undertaken by several companies through the 1960s and 1970s. Rover built a prototype 2.5 L four-cylinder turbo-diesel in 1963,{{citation needed|date=September 2019}} and [[Mercedes-Benz]] used a five-cylinder intercooled turbo-diesel engine in the 1976 [[Mercedes-Benz C111|Mercedes-Benz C111-IID]] experimental vehicle.<ref>{{cite web |title=Mercedes-Benz C 111 |url=https://www.mercedes-benz.com/en/classic/history/c-111/ |website=www.mercedes-benz.com |access-date=29 September 2019 |language=en}}</ref>
The first turbo-diesel production car was the [[Mercedes-Benz W116|Mercedes-Benz 300SD (W116)]] saloon, which was sold in the United States from mid-1978 and powered by the [[Mercedes-Benz OM617 engine|OM617]] five-cylinder engine.<ref>{{cite journal |journal=Popular Science |issue=January 1979}}</ref> A year later, the [[Peugeot 604|Peugeot 604 D Turbo]] became the first turbo-diesel car to be sold in Europe. Turbo-diesel cars began to be widely built and sold in Europe during the late 1980s and early 1990s, a trend that has continued to the present day.<ref>{{cite journal |title=Mercedes-Benz unveils a new kind of performance automobile: the turbodiesel 300 SD Sedan |journal=The Rotarian |volume=August 1978}}</ref><ref name="pettitt">{{cite book |last1=Pettitt |first1=Joe |title=Sport Compact Turbos & Blowers |date=13 May 2005 |publisher=CarTech Inc}}</ref>
Since the 1990s, the [[compression ratio]] of turbo-diesel engines has been dropping, due to better specific power and better exhaust-emission behaviour of turbocharged engines with a lower compression ratio. [[Indirect injection#Diesel engines|Indirect injected engines]] used to have compression ratios of 18.5 or higher. Following the introduction of [[common rail]] engines in the late 1990s, compression ratios decreased to the range of 16.5 to 18.5. Some diesel engines built since 2016 to comply with the [[Euro 6]] exhaust emissions regulations have a compression ratio of 14.0.<ref name="Merker">{{cite book |last1=Merker |first1=Günter P. |last2=Teichmann |first2=Rüdiger |title=Grundlagen Verbrennungsmotoren Funktionsweise, Simulation, Messtechnik |date=2014 |publisher=Springer |isbn=978-3-658-03195-4 |url=https://books.google.com/books?id=e_goBAAAQBAJ |edition=7}}</ref>{{refpage|page=182-183}}
==Characteristics== Turbocharging can greatly increase the power output of a diesel engine, bringing the peak [[power-to-weight ratio]] closer to that of an equivalent petrol engine.<ref>{{cite journal |last1=McCosh |first1=Dan |title=Power for the Future |journal=Popular Science |issue=October 1993}}</ref>
Improvements in power, fuel economy, and [[noise, vibration, and harshness]] in both small and large-capacity turbodiesels over the last decade have spurred their widespread adoption in certain markets, notably in Europe where they (as of 2014) make up over 50% of new car registrations.<ref>{{cite web |title=Second coming - Diesel in America |url=http://www.economist.com/business/displaystory.cfm?story_id=8082092 |website=www.economist.com |access-date=27 September 2019 |date=26 October 2006}}</ref><ref>{{cite news |title=Exxon's contrarian bet on diesel |work=International New York Times |issue=40,847 |date=11 July 2014 |pages=15}}</ref> Turbodiesels are generally considered more flexible for automotive uses than [[naturally aspirated]] diesel engines. Turbodiesels can be designed to have a more acceptable spread of torque over their speed range or, if being built for commercial use, can be designed to improve torque output at a given speed depending on the exact use. Naturally aspirated diesel engines, almost without exception, have a lower power output than a petrol engine of the same capacity whilst the same time requiring stronger (and thus heavier) internal components such as the [[piston]]s and [[crankshaft]] to withstand the greater stresses of the diesel engine's much higher [[compression ratio]]. These factors give naturally aspirated diesels a poor power-to-weight ratio. Turbocharger units weigh very little but can offer significant power, torque, and efficiency improvements. Fitting a turbocharger can bring a diesel engine's power-to-weight ratio up to the same level as an equivalent petrol unit, making turbodiesels desirable for automotive use, where manufacturers aim for comparable power outputs and handling qualities across their range, regardless of the type of power unit chosen.
==See also== *[[Injection pump]] *[[Turbocharged petrol engines]] *[[Variable geometry turbocharger]]
==References== {{reflist|30em}}
[[Category:Diesel engine technology]] [[Category:Turbochargers]] [[Category:Diesel engines]]