Editing Overhead valve engine (section)

=== Overhead camshaft engines ===
{{main|Overhead camshaft engine}}
The first overhead camshaft (OHC) engine dates back to 1902, in the [[Marr (automobile)|Marr]];<ref>{{cite encyclopedia|title= Maudslay|last= Georgano|first= G. N.|author-link= G. N. Georgano|page= [https://archive.org/details/newencyclopediao0000unse_v2r4/page/407 407]|encyclopedia= The New Encyclopedia of Motorcars 1885 to the Present|editor-last= Georgano|editor-first= G. N.|year= 1982|orig-year= 1968|publisher= E. P. Dutton|location= New York|edition= Third|isbn= 0-525-93254-2|lccn= 81-71857|ref= none|url= https://archive.org/details/newencyclopediao0000unse_v2r4/page/407}}</ref> however, use of this design was mostly limited to high-performance cars for many decades. OHC engines slowly became more common from the 1950s to the 1990s, and by the start of the 21st century, the majority of automotive engines (except for some North American V8 engines) used an OHC design.<ref>Now, manufacturers such as [[Honda]] even use OHC motors for lawnmowers!</ref>

At the [[1994 Indianapolis 500]] motor race, Team Penske entered a car powered by the custom-built [[Mercedes-Benz 500I engine|Mercedes-Benz 500I]] pushrod engine. Due to a loophole in the rules, the pushrod engine was allowed to use a larger displacement and higher boost pressure, significantly increasing its power output compared to the OHC engines used by other teams. Team Penske qualified in pole position and won the race by a large margin.

In the early 21st century, several pushrod V8 engines from General Motors and Chrysler used [[variable displacement|cylinder deactivation]] to reduce fuel consumption and exhaust emissions. In 2008, the first production pushrod engine to use [[variable valve timing]] was introduced in the [[Dodge Viper#Fourth generation (ZB II, 2008–2010)|Dodge Viper (fourth generation)]].<ref>{{cite web |url=http://www.sae.org/automag/technewsletter/070402Powertrain/04.htm |title=Automotive Engineering International Online: Powertrain Technology Newsletter |publisher=Sae.org |access-date=2011-09-07 |url-status=dead |archive-url=https://web.archive.org/web/20110805085957/http://www.sae.org/automag/technewsletter/070402Powertrain/04.htm |archive-date=2011-08-05 }}</ref>