Editing Engine (section)

=== Automobiles ===
The first commercially successful automobile, created by [[Karl Benz]], added to the interest in light and powerful engines. The lightweight gasoline internal combustion engine, operating on a four-stroke Otto cycle, has been the most successful for light automobiles, while the thermally more-efficient [[Diesel engine]] is used for trucks and buses. However, in recent years, [[turbocharged]] Diesel engines have become increasingly popular in automobiles, especially outside of the United States, even for quite small cars.

==== Horizontally-opposed pistons ====
In 1896, Karl Benz was granted a patent for his design of the first engine with horizontally opposed pistons. His design created an engine in which the corresponding pistons move in horizontal cylinders and reach top dead center simultaneously, thus automatically balancing each other with respect to their individual momentum. Engines of this design are often referred to as “flat” or “boxer” engines due to their shape and low profile. They were used in the [[Volkswagen Beetle]], the [[Citroën 2CV]], some Porsche and Subaru cars, many [[BMW]] and [[Honda]] [[motorcycle]]s.  Opposed four- and six-cylinder engines continue to be used as [[aircraft engine|a power source]] in small, [[propeller (aeronautics)|propeller-driven]] [[aircraft]].

==== Advancement ====
The continued use of internal combustion engines in automobiles is partly due to the improvement of engine control systems, such as on-board computers providing engine management processes, and electronically controlled fuel injection. Forced air induction by turbocharging and supercharging have increased the power output of smaller displacement engines that are lighter in weight and more fuel-efficient at normal cruise power. Similar changes have been applied to smaller Diesel engines, giving them almost the same performance characteristics as gasoline engines. This is especially evident with the popularity of smaller diesel engine-propelled cars in Europe.  Diesel engines produce lower [[hydrocarbon]] and {{CO2}} emissions, but greater [[Atmospheric particulate matter|particulate]] and {{NOx|link=yes}} pollution, than gasoline engines.<ref name=Harrison2001>{{Citation |title= Pollution: Causes, Effects and Control |first= Roy M. |last= Harrison |author-link=Roy M. Harrison|edition=4th |publisher= [[Royal Society of Chemistry]] |year= 2001 |isbn= 978-0-85404-621-8 }}</ref> Diesel engines are also 40% more fuel efficient than comparable gasoline engines.<ref name=Harrison2001/>

==== Increasing power ====
In the first half of the 20th century, a trend of increasing engine power occurred, particularly in the U.S. models.{{Clarify|reason=As opposed to what models?|date=June 2012}} Design changes incorporated all known methods of increasing engine capacity, including increasing the pressure in the cylinders to improve efficiency, increasing the size of the engine, and increasing the rate at which the engine produces work. The higher forces and pressures created by these changes created engine vibration and size problems that led to stiffer, more compact engines with V and opposed cylinder layouts replacing longer straight-line arrangements.

==== Combustion efficiency ====
Optimal combustion efficiency in passenger vehicles is reached with a coolant temperature of around {{convert|230|F|C|order=flip|0}}.<ref>{{Cite web|last=McKnight|first=Bill|date=August 2017|title=The Electrically Assisted Thermostat|url=https://www.motor.com/magazine-summary/electrically-assisted-thermostat|url-status=live|access-date=2021-03-13|website=Motor.com|language=en-US|archive-date=2021-05-03|archive-url=https://web.archive.org/web/20210503012608/https://www.motor.com/magazine-summary/electrically-assisted-thermostat}}</ref>

==== Engine configuration ====
Earlier automobile engine development produced a much larger range of engines than is in common use today. Engines have ranged from 1- to 16-cylinder designs with corresponding differences in overall size, weight, [[engine displacement]], and cylinder [[Bore (engine)|bores]]. Four cylinders and power ratings from 19 to 120&nbsp;hp (14 to 90&nbsp;kW) were followed in a majority of the models. Several three-cylinder, two-stroke-cycle models were built while most engines had straight or in-line cylinders. There were several V-type models and horizontally opposed two- and four-cylinder makes too. Overhead [[camshaft]]s were frequently employed. The smaller engines were commonly air-cooled and located at the rear of the vehicle; compression ratios were relatively low. The 1970s and 1980s saw an increased interest in improved [[Fuel economy in automobiles|fuel economy]], which caused a return to smaller V-6 and four-cylinder layouts, with as many as five valves per cylinder to improve efficiency. The [[Bugatti Veyron]] 16.4 operates with a [[W16 engine]], meaning that two [[V8 engine|V8]] cylinder layouts are positioned next to each other to create the W&nbsp;shape sharing the same crankshaft.

The largest internal combustion engine ever built is the [[Wärtsilä-Sulzer RTA96-C]], a 14-cylinder, 2-stroke turbocharged diesel engine that was designed to power the ''[[Emma Mærsk]]'', the largest container ship in the world when launched in 2006. This engine has a mass of 2,300 tonnes, and when running at 102&nbsp;rpm (1.7&nbsp;Hz) produces over 80 MW, and can use up to 250 tonnes of fuel per day.