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id="toc-Boxer_configuration" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Boxer_configuration"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.1</span> <span>Boxer configuration</span> </div> </a> <ul id="toc-Boxer_configuration-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-180-degree_V_engine" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#180-degree_V_engine"> <div class="vector-toc-text"> <span class="vector-toc-numb">1.2</span> <span>180-degree V engine</span> </div> </a> <ul id="toc-180-degree_V_engine-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Aviation_use" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Aviation_use"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Aviation use</span> </div> </a> <ul id="toc-Aviation_use-sublist" class="vector-toc-list"> </ul> 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vector-toc-level-2"> <a class="vector-toc-link" href="#Drivetrain_layout"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Drivetrain layout</span> </div> </a> <ul id="toc-Drivetrain_layout-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>History</span> </div> </a> <ul id="toc-History-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Flat engine</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 33 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-33" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">33 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/Bokser_m%C3%BCh%C9%99rriki" title="Bokser mühərriki – Azerbaijani" lang="az" hreflang="az" data-title="Bokser mühərriki" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%AB%E0%A7%8D%E0%A6%B2%E0%A7%8D%E0%A6%AF%E0%A6%BE%E0%A6%9F_%E0%A6%87%E0%A6%9E%E0%A7%8D%E0%A6%9C%E0%A6%BF%E0%A6%A8" title="ফ্ল্যাট ইঞ্জিন – Bangla" lang="bn" hreflang="bn" data-title="ফ্ল্যাট ইঞ্জিন" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%91%D0%BE%D0%BA%D1%81%D0%B5%D1%80%D0%B5%D0%BD_%D0%B4%D0%B2%D0%B8%D0%B3%D0%B0%D1%82%D0%B5%D0%BB" title="Боксерен двигател – Bulgarian" lang="bg" hreflang="bg" data-title="Боксерен двигател" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Motor_boxer" title="Motor boxer – Catalan" lang="ca" hreflang="ca" data-title="Motor boxer" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Boxer_(motor)" title="Boxer (motor) – Czech" lang="cs" hreflang="cs" data-title="Boxer (motor)" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/Boksermotor" title="Boksermotor – Danish" lang="da" hreflang="da" data-title="Boksermotor" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Boxermotor" title="Boxermotor – German" lang="de" hreflang="de" data-title="Boxermotor" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Lamamootor" title="Lamamootor – Estonian" lang="et" hreflang="et" data-title="Lamamootor" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Motor_plano" title="Motor plano – Spanish" lang="es" hreflang="es" data-title="Motor plano" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D9%85%D9%88%D8%AA%D9%88%D8%B1_%D8%AA%D8%AE%D8%AA" title="موتور تخت – Persian" lang="fa" hreflang="fa" data-title="موتور تخت" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Moteur_%C3%A0_plat" title="Moteur à plat – French" lang="fr" hreflang="fr" data-title="Moteur à plat" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-fy mw-list-item"><a href="https://fy.wikipedia.org/wiki/Boksermotor" title="Boksermotor – Western Frisian" lang="fy" hreflang="fy" data-title="Boksermotor" data-language-autonym="Frysk" data-language-local-name="Western Frisian" class="interlanguage-link-target"><span>Frysk</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%88%98%ED%8F%89_%EC%97%94%EC%A7%84" title="수평 엔진 – Korean" lang="ko" hreflang="ko" data-title="수평 엔진" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Mesin_mendatar" title="Mesin mendatar – Indonesian" lang="id" hreflang="id" data-title="Mesin mendatar" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Gagnstrokka_hreyfill" title="Gagnstrokka hreyfill – Icelandic" lang="is" hreflang="is" data-title="Gagnstrokka hreyfill" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Motore_a_cilindri_contrapposti" title="Motore a cilindri contrapposti – Italian" lang="it" hreflang="it" data-title="Motore a cilindri contrapposti" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%9E%D7%A0%D7%95%D7%A2_%D7%91%D7%95%D7%A7%D7%A1%D7%A8" title="מנוע בוקסר – Hebrew" lang="he" hreflang="he" data-title="מנוע בוקסר" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-mn mw-list-item"><a href="https://mn.wikipedia.org/wiki/%D0%91%D0%BE%D0%BA%D1%81%D0%B5%D1%80_%D1%85%D3%A9%D0%B4%D3%A9%D0%BB%D0%B3%D2%AF%D2%AF%D1%80" title="Боксер хөдөлгүүр – Mongolian" lang="mn" hreflang="mn" data-title="Боксер хөдөлгүүр" data-language-autonym="Монгол" data-language-local-name="Mongolian" class="interlanguage-link-target"><span>Монгол</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Boxermotor" title="Boxermotor – Dutch" lang="nl" hreflang="nl" data-title="Boxermotor" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E6%B0%B4%E5%B9%B3%E5%AF%BE%E5%90%91%E3%82%A8%E3%83%B3%E3%82%B8%E3%83%B3" title="水平対向エンジン – Japanese" lang="ja" hreflang="ja" data-title="水平対向エンジン" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Flatmotor" title="Flatmotor – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Flatmotor" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Flatmotor" title="Flatmotor – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Flatmotor" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Silnik_o_przeciwleg%C5%82ych_cylindrach" title="Silnik o przeciwległych cylindrach – Polish" lang="pl" hreflang="pl" data-title="Silnik o przeciwległych cylindrach" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Motor_boxer" title="Motor boxer – Portuguese" lang="pt" hreflang="pt" data-title="Motor boxer" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9E%D0%BF%D0%BF%D0%BE%D0%B7%D0%B8%D1%82%D0%BD%D1%8B%D0%B9_%D0%B4%D0%B2%D0%B8%D0%B3%D0%B0%D1%82%D0%B5%D0%BB%D1%8C" title="Оппозитный двигатель – Russian" lang="ru" hreflang="ru" data-title="Оппозитный двигатель" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Motor_s_proti%C4%BEahl%C3%BDmi_valcami" title="Motor s protiľahlými valcami – Slovak" lang="sk" hreflang="sk" data-title="Motor s protiľahlými valcami" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Protibatni_motor" title="Protibatni motor – Slovenian" lang="sl" hreflang="sl" data-title="Protibatni motor" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%91%D0%BE%D0%BA%D1%81%D0%B5%D1%80_%D0%BC%D0%BE%D1%82%D0%BE%D1%80" title="Боксер мотор – Serbian" lang="sr" hreflang="sr" data-title="Боксер мотор" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Bokserimoottori" title="Bokserimoottori – Finnish" lang="fi" hreflang="fi" data-title="Bokserimoottori" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Boxermotor" title="Boxermotor – Swedish" lang="sv" hreflang="sv" data-title="Boxermotor" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Boks%C3%B6r_tipi_motor" title="Boksör tipi motor – Turkish" lang="tr" hreflang="tr" data-title="Boksör tipi motor" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%9E%D0%BF%D0%BE%D0%B7%D0%B8%D1%82%D0%BD%D0%B8%D0%B9_%D0%B4%D0%B2%D0%B8%D0%B3%D1%83%D0%BD" title="Опозитний двигун – Ukrainian" lang="uk" hreflang="uk" data-title="Опозитний двигун" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E6%B0%B4%E5%B9%B3%E5%B0%8D%E8%87%A5%E5%BC%95%E6%93%8E" title="水平對臥引擎 – Chinese" lang="zh" hreflang="zh" data-title="水平對臥引擎" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q678276#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet 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data-event-name="pinnable-header.vector-appearance.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-appearance.unpin">hide</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Combustion engine using pistons facing to the sides on a common crankshaft</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">For similarly-named engines with two pistons per cylinder, see <a href="/wiki/Opposed-piston_engine" title="Opposed-piston engine">opposed-piston engine</a>.</div> <p class="mw-empty-elt"> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Boxerengineanimation.gif" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Boxerengineanimation.gif/300px-Boxerengineanimation.gif" decoding="async" width="300" height="102" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Boxerengineanimation.gif/450px-Boxerengineanimation.gif 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Boxerengineanimation.gif/600px-Boxerengineanimation.gif 2x" data-file-width="729" data-file-height="249" /></a><figcaption>Animation of a boxer engine</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Benz_Contramotor_IMG_1343_2023-11-25_JM.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/93/Benz_Contramotor_IMG_1343_2023-11-25_JM.jpg/220px-Benz_Contramotor_IMG_1343_2023-11-25_JM.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/93/Benz_Contramotor_IMG_1343_2023-11-25_JM.jpg/330px-Benz_Contramotor_IMG_1343_2023-11-25_JM.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/93/Benz_Contramotor_IMG_1343_2023-11-25_JM.jpg/440px-Benz_Contramotor_IMG_1343_2023-11-25_JM.jpg 2x" data-file-width="4032" data-file-height="3024" /></a><figcaption>Benz Contramotor, the first commercial flat-engine design, ca. 1899</figcaption></figure> <p>A <b>flat engine</b> is a <a href="/wiki/Internal_combustion_engine#Reciprocating_engines" title="Internal combustion engine">piston engine</a> where the cylinders are located on either side of a central <a href="/wiki/Crankshaft" title="Crankshaft">crankshaft</a>. Flat engines are also known as <b>horizontally opposed engines</b>, however this is distinct from the less common <a href="/wiki/Opposed-piston_engine" title="Opposed-piston engine">opposed-piston engine</a> design, whereby each cylinder has two pistons sharing a central combustion chamber. </p><p>The most common configuration of flat engines is the <a href="#Boxer_configuration">boxer engine</a> configuration, in which the pistons of each opposed pair of cylinders move inwards and outwards at the same time. The other configuration is effectively a <a href="/wiki/V_engine" title="V engine">V engine</a> with a 180-degree angle between the cylinder banks: in this configuration each pair of cylinders shares a single crankpin, so that as one piston moves inward, the other moves outward. </p><p>The first flat engine (Benz Contramotor) was built in 1897 by <a href="/wiki/Karl_Benz" class="mw-redirect" title="Karl Benz">Karl Benz</a>. Flat engines have been used in aviation, motorcycle and automobile applications. They are now less common in cars than <a href="/wiki/Straight_engine" title="Straight engine">straight engines</a> (for engines with fewer than six cylinders) and <a href="/wiki/V_engine" title="V engine">V engines</a> (for engines with six or more cylinders). Flat engines are more common in aircraft, where straight engines are a rarity and V engines have almost vanished except in historical aircraft. They have even replaced <a href="/wiki/Radial_engine" title="Radial engine">radial engines</a> in many smaller installations. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Design">Design</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Flat_engine&action=edit&section=1" title="Edit section: Design"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-More_citations_needed_section plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></div></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/Flat_engine" title="Special:EditPage/Flat engine">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed.</span> <span class="date-container"><i>(<span class="date">February 2021</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Moteurs_%C3%A0_Plat_-_V_%C3%A0_180%C2%B0_vs._Boxer.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7a/Moteurs_%C3%A0_Plat_-_V_%C3%A0_180%C2%B0_vs._Boxer.png/220px-Moteurs_%C3%A0_Plat_-_V_%C3%A0_180%C2%B0_vs._Boxer.png" decoding="async" width="220" height="159" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7a/Moteurs_%C3%A0_Plat_-_V_%C3%A0_180%C2%B0_vs._Boxer.png/330px-Moteurs_%C3%A0_Plat_-_V_%C3%A0_180%C2%B0_vs._Boxer.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/7a/Moteurs_%C3%A0_Plat_-_V_%C3%A0_180%C2%B0_vs._Boxer.png/440px-Moteurs_%C3%A0_Plat_-_V_%C3%A0_180%C2%B0_vs._Boxer.png 2x" data-file-width="800" data-file-height="579" /></a><figcaption>Difference between two flat 6 cylinder engines: 180° V on the left, boxer on the right</figcaption></figure> <p>The advantages of flat engines are a short length, low <a href="/wiki/Centre_of_mass" class="mw-redirect" title="Centre of mass">centre of mass</a> and suitability for <a href="/wiki/Air-cooled_engine" title="Air-cooled engine">air cooling</a> (due to the well-exposed, large-surface-area cylinders and cylinder heads, and their short length). </p><p>Compared with the more common <a href="/wiki/Straight_engine" title="Straight engine">straight engines</a>, flat engines have better <a href="/wiki/Primary_balance" class="mw-redirect" title="Primary balance">primary balance</a> (resulting in less vibration);<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> however, the disadvantages are increased width and the need to have two cylinder heads. Compared with <a href="/wiki/V_engine" title="V engine">V engines</a> – the most common layout for engines with six cylinders or more – flat engines again have a lower centre of mass, and, for six-cylinders, better primary balance; the disadvantage is again their being wider.<sup id="cite_ref-why-subaru_2-0" class="reference"><a href="#cite_note-why-subaru-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>The most common usages of flat engines are: </p> <ul><li><a href="/wiki/Flat-twin_engine" title="Flat-twin engine">Flat-twin engines</a> are mostly used in motorcycles. Occasionally they have been used in light cars, aircraft and industrial applications, mostly up until the 1960s.</li> <li><a href="/wiki/Flat-four_engine" title="Flat-four engine">Flat-four engines</a> are mostly used in cars (most notably in the earlier <a href="/wiki/Volkswagen" title="Volkswagen">Volkswagen</a> <a href="/wiki/Volkswagen_Beetle" title="Volkswagen Beetle">Types 1</a> to <a href="/wiki/Volkswagen_Type_4" title="Volkswagen Type 4">4</a>, and by <a href="/wiki/Subaru" title="Subaru">Subaru</a><sup id="cite_ref-why-subaru_2-1" class="reference"><a href="#cite_note-why-subaru-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> in most of their models), and have occasionally been used in motorcycles. Their most common use is in smaller single-engine <a href="/wiki/General_aviation" title="General aviation">general-aviation</a> aircraft, for which they are still manufactured and used to this day.</li> <li><a href="/wiki/Flat-six_engine" title="Flat-six engine">Flat-six engines</a> are mostly used in aircraft and cars (particularly by the <a href="/wiki/Porsche" title="Porsche">Porsche</a> 911 sports car), and have occasionally been used in motorcycles.</li> <li><a href="/wiki/Flat-eight_engine" title="Flat-eight engine">Flat-eight engines</a> have been used in several racing cars, mostly by Porsche in the 1960s.</li> <li><a href="/wiki/Flat-ten_engine" title="Flat-ten engine">Flat-ten engines</a> are not known to have reached production. A prototype road car engine was built by <a href="/wiki/Chevrolet" title="Chevrolet">Chevrolet</a> in the 1960s.</li> <li><a href="/wiki/Flat-twelve_engine" title="Flat-twelve engine">Flat-twelve engines</a> have been used in various racing cars, notably the <a href="/wiki/Porsche_917K" class="mw-redirect" title="Porsche 917K">Porsche 917K</a>, during the 1960s and 1970s, and in <a href="/wiki/Ferrari" title="Ferrari">Ferrari</a> road cars from 1973 to 1996.</li> <li><a href="/wiki/Flat-sixteen_engine" title="Flat-sixteen engine">Flat-sixteen engines</a> are not known to have reached production. Prototype racing car engines were built by <a href="/wiki/Coventry_Climax" title="Coventry Climax">Coventry</a> and Porsche in the 1960s and 1970s.</li></ul> <div class="mw-heading mw-heading3"><h3 id="Boxer_configuration">Boxer configuration <span class="anchor" id="Boxer_engine"></span></h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Flat_engine&action=edit&section=2" title="Edit section: Boxer configuration"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:R68-opposed-cylinders.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/R68-opposed-cylinders.jpg/220px-R68-opposed-cylinders.jpg" decoding="async" width="220" height="164" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/R68-opposed-cylinders.jpg/330px-R68-opposed-cylinders.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/63/R68-opposed-cylinders.jpg/440px-R68-opposed-cylinders.jpg 2x" data-file-width="800" data-file-height="595" /></a><figcaption>1954 <a href="/wiki/BMW_R68" title="BMW R68">BMW R68</a> flat-twin boxer engine</figcaption></figure> <p>Most flat engines use a "boxer" configuration, where each pair of opposing pistons move inwards and outwards at the same time, somewhat like boxing competitors punching their gloves together before a fight.<sup id="cite_ref-Bonk_3-0" class="reference"><a href="#cite_note-Bonk-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> Boxer engines have low vibration, being they are the only common configuration that has no unbalanced forces, regardless of the number of pairs of cylinders. Boxer engines therefore do not require either a <a href="/wiki/Balance_shaft" title="Balance shaft">balance shaft</a><sup id="cite_ref-Hanlon_4-0" class="reference"><a href="#cite_note-Hanlon-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> or counterweights on the <a href="/wiki/Crankshaft" title="Crankshaft">crankshaft</a> to balance the weight of the reciprocating parts. However, a <a href="/wiki/Couple_(mechanics)#Applications" title="Couple (mechanics)">rocking couple</a> is present, since each cylinder is slightly offset from the other member of its pair due to the distance between the <a href="/wiki/Crankpin" title="Crankpin">crankpins</a> along the crankshaft.<sup id="cite_ref-Bonk_3-1" class="reference"><a href="#cite_note-Bonk-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="180-degree_V_engine">180-degree V engine</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Flat_engine&action=edit&section=3" title="Edit section: 180-degree V engine"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>An alternative configuration for flat engines is as a 180-degree <a href="/wiki/V_engine" title="V engine">V engine</a>, which has been used on most twelve-cylinder flat engines. In this configuration, each pair of pistons shares a <a href="/wiki/Crankpin" title="Crankpin">crankpin</a>, this being simpler than the boxer configuration, where each piston has its own separate crankpin. </p> <div class="mw-heading mw-heading2"><h2 id="Aviation_use">Aviation use</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Flat_engine&action=edit&section=4" title="Edit section: Aviation use"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Puch_Flugmotor_Patent_AT_48877_1909-11-08.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Puch_Flugmotor_Patent_AT_48877_1909-11-08.png/220px-Puch_Flugmotor_Patent_AT_48877_1909-11-08.png" decoding="async" width="220" height="189" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Puch_Flugmotor_Patent_AT_48877_1909-11-08.png/330px-Puch_Flugmotor_Patent_AT_48877_1909-11-08.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4e/Puch_Flugmotor_Patent_AT_48877_1909-11-08.png/440px-Puch_Flugmotor_Patent_AT_48877_1909-11-08.png 2x" data-file-width="488" data-file-height="420" /></a><figcaption>Twin-boxer of <a href="/wiki/Johann_Puch" title="Johann Puch">Johann Puch</a>, Patent AT 48877 (1909)</figcaption></figure> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Riedelanlasser.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Riedelanlasser.jpg/220px-Riedelanlasser.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Riedelanlasser.jpg/330px-Riedelanlasser.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Riedelanlasser.jpg/440px-Riedelanlasser.jpg 2x" data-file-width="1025" data-file-height="768" /></a><figcaption>World War II-era Riedel starter motor</figcaption></figure> <p>In 1902, the Pearse monoplane (which would later become one of the first aircraft to achieve flight) was powered by a flat-twin engine. Amongst the first commercially-produced aircraft to use a flat engine was the 1909 <a href="/wiki/Santos-Dumont_Demoiselle" title="Santos-Dumont Demoiselle">Santos-Dumont Demoiselle</a> range of aeroplanes, which was powered by boxer-twin engines.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2021)">citation needed</span></a></i>]</sup> </p><p>Several boxer-four engines have been produced specifically for light aircraft. A number of manufacturers produced boxer-six aircraft engines during the 1930s and 1940s.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2021)">citation needed</span></a></i>]</sup> </p><p>During World War II, a boxer-twin engine called the "Riedel starter" was used as a starter motor/mechanical <a href="/wiki/Auxiliary_power_unit#As_mechanical_"startup"_APUs_for_jet_engines" title="Auxiliary power unit">APU</a> for the early German jet engines, such as the <a href="/wiki/Junkers_Jumo_004" title="Junkers Jumo 004">Junkers Jumo 004</a> and <a href="/wiki/BMW_003" title="BMW 003">BMW 003</a>. Designed by <a href="/wiki/Norbert_Riedel" title="Norbert Riedel">Norbert Riedel</a>, these engines have a very <a href="/wiki/Stroke_ratio#Oversquare_or_short-stroke_engine" title="Stroke ratio">oversquare</a> stroke ratio of 2:1 so that they could fit within the intake diverter, directly forward of the turbine compressor.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2021)">citation needed</span></a></i>]</sup> </p> <div style="clear:right;" class=""></div> <div class="mw-heading mw-heading2"><h2 id="Motorcycle_use">Motorcycle use</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Flat_engine&action=edit&section=5" title="Edit section: Motorcycle use"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Flat engines offer several advantages for motorcycles including a low <a href="/wiki/Centre_of_mass" class="mw-redirect" title="Centre of mass">centre of mass</a>, low vibration, suitability for shaft drive, and equal cooling of the cylinders (for air-cooled engines).<sup id="cite_ref-English_5-0" class="reference"><a href="#cite_note-English-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Szymezak1_6-0" class="reference"><a href="#cite_note-Szymezak1-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> The most common design of flat engine for motorcycles is the boxer-twin, beginning with the 1905 Fée flat-twin engine, manufactured by the Light Motors Company, which was the first production motorcycle engine.<sup id="cite_ref-TMCfuture_7-0" class="reference"><a href="#cite_note-TMCfuture-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> <a href="/wiki/BMW_Motorrad" title="BMW Motorrad">BMW Motorrad</a> have a long history of boxer-twin motorcycles, beginning in 1923 with the <a href="/wiki/BMW_R32" title="BMW R32">BMW R32</a><sup id="cite_ref-English_5-1" class="reference"><a href="#cite_note-English-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p><p>Several motorcycles have been produced with flat-four engines, such as the 1938–1939 <a href="/wiki/Z%C3%BCndapp" title="Zündapp">Zündapp K800</a> and the 1974–1987 <a href="/wiki/Honda_Gold_Wing" title="Honda Gold Wing">Honda Gold Wing</a>. In 1987, the Honda Gold Wing engine was upsized to a flat-six design.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Automotive_use">Automotive use</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Flat_engine&action=edit&section=6" title="Edit section: Automotive use"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1237032888/mw-parser-output/.tmulti">.mw-parser-output .tmulti .multiimageinner{display:flex;flex-direction:column}.mw-parser-output .tmulti .trow{display:flex;flex-direction:row;clear:left;flex-wrap:wrap;width:100%;box-sizing:border-box}.mw-parser-output .tmulti .tsingle{margin:1px;float:left}.mw-parser-output .tmulti .theader{clear:both;font-weight:bold;text-align:center;align-self:center;background-color:transparent;width:100%}.mw-parser-output .tmulti .thumbcaption{background-color:transparent}.mw-parser-output .tmulti .text-align-left{text-align:left}.mw-parser-output .tmulti .text-align-right{text-align:right}.mw-parser-output .tmulti .text-align-center{text-align:center}@media all and (max-width:720px){.mw-parser-output .tmulti .thumbinner{width:100%!important;box-sizing:border-box;max-width:none!important;align-items:center}.mw-parser-output .tmulti .trow{justify-content:center}.mw-parser-output .tmulti .tsingle{float:none!important;max-width:100%!important;box-sizing:border-box;text-align:center}.mw-parser-output .tmulti .tsingle .thumbcaption{text-align:left}.mw-parser-output .tmulti .trow>.thumbcaption{text-align:center}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .tmulti .multiimageinner img{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .tmulti .multiimageinner img{background-color:white}}</style><div class="thumb tmulti tright"><div class="thumbinner multiimageinner" style="width:224px;max-width:224px"><div class="trow"><div class="tsingle" style="width:222px;max-width:222px"><div class="thumbimage"><span typeof="mw:File"><a href="/wiki/File:Diesel_Engine_Type_DS140_2C_Hino.jpg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/6/64/Diesel_Engine_Type_DS140_2C_Hino.jpg/220px-Diesel_Engine_Type_DS140_2C_Hino.jpg" decoding="async" width="220" height="148" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/64/Diesel_Engine_Type_DS140_2C_Hino.jpg/330px-Diesel_Engine_Type_DS140_2C_Hino.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/64/Diesel_Engine_Type_DS140_2C_Hino.jpg/440px-Diesel_Engine_Type_DS140_2C_Hino.jpg 2x" data-file-width="2295" data-file-height="1547" /></a></span></div><div class="thumbcaption">1969 <a href="/wiki/Hino_Motors" title="Hino Motors">Hino Motors</a> DS140 boxer-twelve diesel engine</div></div></div><div class="trow"><div class="tsingle" style="width:222px;max-width:222px"><div class="thumbimage"><span typeof="mw:File"><a href="/wiki/File:ChassisT11.JPG" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b2/ChassisT11.JPG/220px-ChassisT11.JPG" decoding="async" width="220" height="154" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b2/ChassisT11.JPG/330px-ChassisT11.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b2/ChassisT11.JPG/440px-ChassisT11.JPG 2x" data-file-width="891" data-file-height="625" /></a></span></div><div class="thumbcaption">1923-1927 <a href="/wiki/Tatra_11" title="Tatra 11">Tatra 11</a> chassis and engine— front-mounted flat-twin engine with rear-wheel drive</div></div></div></div></div> <p>When used in cars, advantages of flat engines are a low <a href="/wiki/Centre_of_mass" class="mw-redirect" title="Centre of mass">centre of mass</a> (which improves the handling of the car),<sup id="cite_ref-Hanlon_4-1" class="reference"><a href="#cite_note-Hanlon-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> short length, low vibration and suitability for air cooling (due to the well exposed, large surface area, cylinder heads and short length).<sup id="cite_ref-FOOTNOTENunney198812–13_9-0" class="reference"><a href="#cite_note-FOOTNOTENunney198812–13-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> However the larger width of flat engines (compared with the more common inline and V layouts) is a drawback, particularly when the engine is located between the steered wheels.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2021)">citation needed</span></a></i>]</sup> </p><p>Flat engines were used by various automobile manufacturers – mostly with a boxer-four design – up until the late 1990s. Since then, only Porsche and Subaru have remained as significant manufacturers of flat engines.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2021)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading3"><h3 id="Drivetrain_layout">Drivetrain layout</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Flat_engine&action=edit&section=7" title="Edit section: Drivetrain layout"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-More_citations_needed_section plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></div></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/Flat_engine" title="Special:EditPage/Flat engine">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed.</span> <span class="date-container"><i>(<span class="date">February 2021</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <p>Due to the short length of flat engines, locating a flat engine outside of the car's <a href="/wiki/Wheelbase" title="Wheelbase">wheelbase</a> results in minimal overhang.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> Therefore, many cars with flat engines have used a <a href="/wiki/Rear-engine,_rear-wheel-drive_layout" title="Rear-engine, rear-wheel-drive layout">rear-engine, rear-wheel-drive layout</a>. Examples include the flat-twin <a href="/wiki/BMW_600" title="BMW 600">BMW 600</a> (1957–1959) and <a href="/wiki/BMW_700" title="BMW 700">BMW 700</a> (1959–1965); the flat-four <a href="/wiki/Tatra_97" title="Tatra 97">Tatra 97</a> (1936–1939), <a href="/wiki/Volkswagen_Beetle" title="Volkswagen Beetle">Volkswagen Beetle</a> (1938–2003) and <a href="/wiki/Porsche_356" title="Porsche 356">Porsche 356</a> (1948–1965); and the flat-six <a href="/wiki/Chevrolet_Corvair" title="Chevrolet Corvair">Chevrolet Corvair</a> (1959–1969), <a href="/wiki/Porsche_911" title="Porsche 911">Porsche 911</a> (1963-present), and <a href="/wiki/Tucker_48" title="Tucker 48">Tucker 48</a> (1947–1948). </p><p>The opposite layout, <a href="/wiki/Front-engine,_front-wheel-drive_layout" title="Front-engine, front-wheel-drive layout">front-engine front-wheel drive</a>, was also common for cars with flat engines. Examples include the <a href="/wiki/Citro%C3%ABn_2CV" title="Citroën 2CV">Citroën 2CV</a> (1948–1990), <a href="/wiki/Panhard_Dyna_X" title="Panhard Dyna X">Panhard Dyna X</a> (1948–1954), <a href="/wiki/Lancia_Flavia" title="Lancia Flavia">Lancia Flavia</a> (1961–1970), <a href="/wiki/Citro%C3%ABn_GS" title="Citroën GS">Citroën GS</a> (1970–1986), <a href="/wiki/Alfa_Romeo_Alfasud" title="Alfa Romeo Alfasud">Alfa Romeo Alfasud</a> (1971–1989) and <a href="/wiki/Subaru_Leone" title="Subaru Leone">Subaru Leone</a> (1971–1994). </p><p>Subaru have been producing cars with a <a href="/wiki/Front-engine,_four-wheel-drive_layout" title="Front-engine, four-wheel-drive layout">front-engine, four-wheel-drive layout</a> powered by flat engines (mostly boxer-four engines) since 1971. Examples include the <a href="/wiki/Subaru_Leone" title="Subaru Leone">Subaru Leone</a> (1971–1994), <a href="/wiki/Subaru_Legacy" title="Subaru Legacy">Subaru Legacy</a> (1989-present) and <a href="/wiki/Subaru_Impreza" title="Subaru Impreza">Subaru Impreza</a> (1992–present). The front half-shafts come out of a front differential that is part of the gearbox. A rear driveshaft connects the gearbox to the rear half-shafts. </p><p>The traditional <a href="/wiki/Front-engine,_rear-wheel-drive_layout" title="Front-engine, rear-wheel-drive layout">front-engine, rear-wheel-drive layout</a> is relatively uncommon for cars with flat engines, however some examples include the <a href="/wiki/Toyota_86" title="Toyota 86">Toyota 86 / Subaru BRZ</a> (2012–present), <a href="/wiki/Jowett_Javelin" title="Jowett Javelin">Jowett Javelin</a> (1947–1953), <a href="/wiki/Glas_Isar" title="Glas Isar">Glas Isar</a> (1958–1965) and the <a href="/wiki/Tatra_11" title="Tatra 11">Tatra 11</a> (1923–1927). </p> <div class="mw-heading mw-heading3"><h3 id="History">History</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Flat_engine&action=edit&section=8" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1251242444"><table class="box-More_citations_needed_section plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></div></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/Flat_engine" title="Special:EditPage/Flat engine">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed.</span> <span class="date-container"><i>(<span class="date">February 2021</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1237032888/mw-parser-output/.tmulti"><div class="thumb tmulti tright"><div class="thumbinner multiimageinner" style="width:224px;max-width:224px"><div class="trow"><div class="tsingle" style="width:222px;max-width:222px"><div class="thumbimage"><span typeof="mw:File"><a href="/wiki/File:Volkswagen_motor_cut_1945.JPG" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7e/Volkswagen_motor_cut_1945.JPG/220px-Volkswagen_motor_cut_1945.JPG" decoding="async" width="220" height="197" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7e/Volkswagen_motor_cut_1945.JPG/330px-Volkswagen_motor_cut_1945.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/7e/Volkswagen_motor_cut_1945.JPG/440px-Volkswagen_motor_cut_1945.JPG 2x" data-file-width="1710" data-file-height="1534" /></a></span></div><div class="thumbcaption"><a href="/wiki/Volkswagen_air-cooled_engine" title="Volkswagen air-cooled engine">Volkswagen air-cooled</a> boxer-four engine</div></div></div><div class="trow"><div class="tsingle" style="width:222px;max-width:222px"><div class="thumbimage"><span typeof="mw:File"><a href="/wiki/File:Subaru_BRZ_engine_(20413082204).jpg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/95/Subaru_BRZ_engine_%2820413082204%29.jpg/220px-Subaru_BRZ_engine_%2820413082204%29.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/95/Subaru_BRZ_engine_%2820413082204%29.jpg/330px-Subaru_BRZ_engine_%2820413082204%29.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/95/Subaru_BRZ_engine_%2820413082204%29.jpg/440px-Subaru_BRZ_engine_%2820413082204%29.jpg 2x" data-file-width="2592" data-file-height="1944" /></a></span></div><div class="thumbcaption">2012-present <a href="/wiki/Subaru_FA_engine" title="Subaru FA engine">Subaru FA20</a> boxer-four engine</div></div></div></div></div> <p>The first flat engine was produced in 1897 by German engineer <a href="/wiki/Karl_Benz" class="mw-redirect" title="Karl Benz">Karl Benz</a>.<sup id="cite_ref-English_5-2" class="reference"><a href="#cite_note-English-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Called the <i>kontra</i> engine, it was a boxer-twin design. Early uses of flat engines in cars include the 1900 <a href="/wiki/Lanchester_Motor_Company" title="Lanchester Motor Company">Lanchester 8 hp Phaeton</a> boxer-twin, the 1901 <a href="/wiki/Wilson-Pilcher" title="Wilson-Pilcher">Wilson-Pilcher</a> boxer-four,<sup id="cite_ref-Automotor_12-0" class="reference"><a href="#cite_note-Automotor-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> the 1904 Wilson-Pilcher <i>18/24 HP</i> boxer-six and the 1903 <a href="/wiki/Ford_Model_A_(1903%E2%80%931904)" class="mw-redirect" title="Ford Model A (1903–1904)">Ford Model A</a>, the 1904 <a href="/wiki/Ford_Model_C" title="Ford Model C">Ford Model C</a> and the 1905 <a href="/wiki/Ford_Model_F" title="Ford Model F">Ford Model F</a>.<sup id="cite_ref-Kimes_13-0" class="reference"><a href="#cite_note-Kimes-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </p><p>In 1938, the <a href="/wiki/Volkswagen_Beetle" title="Volkswagen Beetle">Volkswagen Beetle</a> (then called the "KdF-Wagen") was released with a rear-mounted flat-four engine. This <a href="/wiki/Volkswagen_air-cooled_engine" title="Volkswagen air-cooled engine">Volkswagen air-cooled engine</a> was produced for many years and also used in the <a href="/wiki/Volkswagen_Type_2" title="Volkswagen Type 2">Volkswagen Type 2</a> (Transporter, Kombi or Microbus), the <a href="/wiki/Volkswagen_Karmann_Ghia" title="Volkswagen Karmann Ghia">Volkswagen Karmann Ghia</a> sports car and the <a href="/wiki/Volkswagen_Type_3" title="Volkswagen Type 3">Volkswagen Type 3</a> compact car. A water-cooled version, known as the <a href="/wiki/Wasserboxer" title="Wasserboxer">Wasserboxer</a>, was introduced in 1982 and eventually replaced the air-cooled versions. </p><p>The majority of sports cars throughout Porsche's history are powered by flat engines, beginning with its first car; the 1948-1965 <a href="/wiki/Porsche_356" title="Porsche 356">Porsche 356</a> used an air-cooled boxer-four engine. Also using boxer-four engines were the 1969-1976 <a href="/wiki/Porsche_914" title="Porsche 914">Porsche 914</a>, the 1965-1969 <a href="/wiki/Porsche_912" title="Porsche 912">Porsche 912</a> and the 2016-present <a href="/wiki/Porsche_982" class="mw-redirect" title="Porsche 982">Porsche Boxster/Cayman (982)</a>. The <a href="/wiki/Porsche_911_(classic)" title="Porsche 911 (classic)">Porsche 911</a> has exclusively used boxer-six engines from its introduction in 1964 until the present. In 1997, the Porsche 911 switched from being air-cooled to water-cooled. </p><p><a href="/wiki/Porsche_flat-eight_engines" title="Porsche flat-eight engines">Porsche flat-eight engines</a> were used in various racing cars throughout the 1960s, such as the 1962 <a href="/wiki/Porsche_804" title="Porsche 804">Porsche 804</a> Formula One car and the 1968-1971 <a href="/wiki/Porsche_908" title="Porsche 908">Porsche 908</a> sports car. A flat-twelve engine was also produced by Porsche for the 1969-1973 <a href="/wiki/Porsche_917" title="Porsche 917">Porsche 917</a> sports car. </p><p><a href="/wiki/Chevrolet" title="Chevrolet">Chevrolet</a> used a horizontally opposed air-cooled 6 cylinder engine in its <a href="/wiki/Chevrolet_Corvair" title="Chevrolet Corvair">Corvair</a> line during its entire production run from 1960 to 1969 in various applications and power ratings, including one of the first uses of a turbocharger in a mass-produced automobile. </p><p>The <a href="/wiki/Subaru_EA_engine" title="Subaru EA engine">Subaru EA engine</a> was introduced in 1966 and began <a href="/wiki/Subaru" title="Subaru">Subaru</a>'s line of boxer-four engines that remain in production to this day.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> Most of Subaru's models are powered by a boxer-four engine in either naturally aspirated or turbocharged form. A print ad for the 1973 <a href="/wiki/Subaru_GL" class="mw-redirect" title="Subaru GL">Subaru GL</a> coupe referred to the engine as "quadrozontal".<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> The company also produced boxer-six engines from 1988 to 1996 and 2001–2019.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> In 2008, the <a href="/wiki/List_of_Subaru_engines#Subaru_EE_engine_(diesel)" title="List of Subaru engines">Subaru EE</a> engine became the world's first passenger car diesel boxer engine. This engine is a turbocharged boxer-four with common rail fuel injection.<sup id="cite_ref-Hanlon_4-2" class="reference"><a href="#cite_note-Hanlon-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> </p><p>Ferrari used flat-twelve engines for various Formula One cars in the 1970s. A road car flat-twelve engine (using a 180-degree V12 configuration) was used for the 1973-1984 <a href="/wiki/Ferrari_Berlinetta_Boxer" title="Ferrari Berlinetta Boxer">Ferrari Berlinetta Boxer</a>, 1984-1996 <a href="/wiki/Ferrari_Testarossa" title="Ferrari Testarossa">Ferrari Testarossa</a> and their derivatives.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> </p><p>Toyota uses the designation <i>Toyota 4U-GSE</i> for the boxer-four engine in the Toyota-badged versions of the <a href="/wiki/Toyota_86" title="Toyota 86">Toyota 86 / Subaru BRZ</a> twins, although the engine is actually designed and built by Subaru as the <a href="/wiki/Subaru_FA_engine#FA20" title="Subaru FA engine">Subaru FA20</a> engine.<sup id="cite_ref-Bonk_3-2" class="reference"><a href="#cite_note-Bonk-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Flat_engine&action=edit&section=9" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/H_engine" title="H engine">H engine</a></li> <li><a href="/wiki/V_engine" title="V engine">V engine</a></li> <li><a href="/wiki/W_engine" title="W engine">W engine</a></li> <li><a href="/wiki/X_engine" title="X engine">X engine</a></li> <li><a href="/wiki/Radial_engine" title="Radial engine">Radial engine</a></li> <li><a href="/wiki/History_of_the_internal_combustion_engine" title="History of the internal combustion engine">History of the internal combustion engine</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Flat_engine&action=edit&section=10" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width" style="column-width: 35em;"> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.caranddriver.com/features/a15126436/the-physics-of-engine-cylinder-bank-angles-feature/">"The Physics of: Engine Cylinder-Bank Angles"</a>. <i>www.caranddriver.com</i>. 14 October 2019<span class="reference-accessdate">. Retrieved <span class="nowrap">18 October</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.caranddriver.com&rft.atitle=The+Physics+of%3A+Engine+Cylinder-Bank+Angles&rft.date=2019-10-14&rft_id=https%3A%2F%2Fwww.caranddriver.com%2Ffeatures%2Fa15126436%2Fthe-physics-of-engine-cylinder-bank-angles-feature%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFlat+engine" class="Z3988"></span></span> </li> <li id="cite_note-why-subaru-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-why-subaru_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-why-subaru_2-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.subaru.com.au/why-subaru/performance">"Subaru Car Performance"</a>. Australia: Subaru<span class="reference-accessdate">. Retrieved <span class="nowrap">1 July</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Subaru+Car+Performance&rft.place=Australia&rft.pub=Subaru&rft_id=https%3A%2F%2Fwww.subaru.com.au%2Fwhy-subaru%2Fperformance&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFlat+engine" class="Z3988"></span></span> </li> <li id="cite_note-Bonk-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-Bonk_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Bonk_3-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Bonk_3-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBonk2013" class="citation web cs1">Bonk, Aaron (7 February 2013). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140227052947/http://www.superstreetonline.com/techarticles/sstp_1301_how_boxer_engines_work/">"How Boxer Engines Work"</a>. <i>Super Street Magazine</i>. Source Interlink Media. Archived from <a rel="nofollow" class="external text" href="http://www.superstreetonline.com/techarticles/sstp_1301_how_boxer_engines_work/">the original</a> on 27 February 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">21 December</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Super+Street+Magazine&rft.atitle=How+Boxer+Engines+Work&rft.date=2013-02-07&rft.aulast=Bonk&rft.aufirst=Aaron&rft_id=http%3A%2F%2Fwww.superstreetonline.com%2Ftecharticles%2Fsstp_1301_how_boxer_engines_work%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFlat+engine" class="Z3988"></span></span> </li> <li id="cite_note-Hanlon-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-Hanlon_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Hanlon_4-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Hanlon_4-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHanlon2001" class="citation news cs1">Hanlon, Mike (7 February 2001). <a rel="nofollow" class="external text" href="http://www.gizmag.com/go/6800/">"The world's first horizontally-opposed turbo diesel engine"</a>. <i>Gizmag</i><span class="reference-accessdate">. Retrieved <span class="nowrap">20 December</span> 2013</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Gizmag&rft.atitle=The+world%27s+first+horizontally-opposed+turbo+diesel+engine&rft.date=2001-02-07&rft.aulast=Hanlon&rft.aufirst=Mike&rft_id=http%3A%2F%2Fwww.gizmag.com%2Fgo%2F6800%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AFlat+engine" class="Z3988"></span></span> </li> <li id="cite_note-English-5"><span class="mw-cite-backlink">^ <a href="#cite_ref-English_5-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-English_5-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-English_5-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFEnglish2010" class="citation news cs1">English, Bob (29 April 2010). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20131220085552/http://www.theglobeandmail.com/globe-drive/car-life/classic-cars/the-engine-that-benz-built-still-survives/article4317376/">"The engine that Benz built still survives"</a>. <i>The Globe and Mail</i>. Canada. Archived from <a rel="nofollow" class="external text" href="https://www.theglobeandmail.com/globe-drive/car-life/classic-cars/the-engine-that-benz-built-still-survives/article4317376/">the original</a> on 20 December 2013<span class="reference-accessdate">. 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Fédération des GoldWing Club de France. Archived from <a rel="nofollow" class="external text" href="http://fgwcf.org/rever/debut_legende.asp">the original</a> on 19 December 2013<span class="reference-accessdate">. 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template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Piston_engine_configurations" title="Special:EditPage/Template:Piston engine configurations"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Engine_configurations_for_piston_engines" style="font-size:114%;margin:0 4em"><a href="/wiki/Engine_configuration" title="Engine configuration">Engine configurations</a> for <a href="/wiki/Piston_engine" class="mw-redirect" title="Piston engine">piston engines</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Type</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Newcomen_atmospheric_engine" title="Newcomen atmospheric engine">Atmospheric</a></li> <li><a href="/wiki/Axial_engine" title="Axial engine">Axial</a></li> <li><a href="/wiki/Beam_engine" title="Beam engine">Beam</a> <ul><li><a href="/wiki/Cornish_steam_engine" class="mw-redirect" title="Cornish steam engine">Cornish</a></li> <li><a href="/wiki/Rotative_beam_engine" class="mw-redirect" title="Rotative beam engine">Rotative</a></li></ul></li> <li><a href="/wiki/Bourke_engine" title="Bourke engine">Bourke</a></li> <li><a href="/wiki/Cam_engine" title="Cam engine">Cam engine</a></li> <li><a href="/wiki/Camless_piston_engine" title="Camless piston engine">Camless</a></li> <li><a href="/wiki/Compound_steam_engine" title="Compound steam engine">Compound</a></li> <li><a href="/wiki/Double-acting_cylinder" class="mw-redirect" title="Double-acting cylinder">Double-acting cylinder</a></li> <li><a href="/wiki/Flathead_engine" title="Flathead engine">Flathead</a></li> <li><a href="/wiki/Free-piston_engine" title="Free-piston engine">Free-piston</a> <ul><li><a href="/wiki/Stelzer_engine" title="Stelzer engine">Stelzer</a></li></ul></li> <li><a href="/wiki/Hemi_engine" class="mw-redirect" title="Hemi engine">Hemi</a></li> <li><a href="/wiki/Heron_cylinder_head" title="Heron cylinder head">Heron head</a></li> <li><a href="/wiki/IOE_engine" title="IOE engine">Intake over exhaust</a></li> <li><a href="/wiki/Oscillating_cylinder_steam_engine" title="Oscillating cylinder steam engine">Oscillating cylinder</a></li> <li><a href="/wiki/Opposed-piston_engine" title="Opposed-piston engine">Opposed-piston</a></li> <li><a href="/wiki/Overhead_camshaft_engine" title="Overhead camshaft engine">Overhead camshaft</a></li> <li><a href="/wiki/Overhead_valve_engine" title="Overhead valve engine">Overhead valve</a></li> <li><a href="/wiki/Pent-roof_combustion_chamber" title="Pent-roof combustion chamber">Pentroof</a></li> <li><a href="/wiki/Rotary_engine" title="Rotary engine">Rotary</a></li> <li><a href="/wiki/Single-acting_cylinder" class="mw-redirect" title="Single-acting cylinder">Single-acting cylinder</a></li> <li><a href="/wiki/Split_cycle_engine" class="mw-redirect" title="Split cycle engine">Split cycle</a></li> <li><a href="/wiki/Swing-piston_engine" title="Swing-piston engine">Swing-piston</a></li> <li><a href="/wiki/Uniflow_steam_engine" title="Uniflow steam engine">Uniflow</a></li> <li><a href="/wiki/Watt_steam_engine" title="Watt steam engine">Watt</a></li> <li><a href="/wiki/Chrysler_wedge_engine" class="mw-redirect" title="Chrysler wedge engine">Wedge</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Stroke_(engine)" title="Stroke (engine)">Stroke cycles</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Two-stroke_engine" title="Two-stroke engine">Two-stroke</a></li> <li><a href="/wiki/Four-stroke_engine" title="Four-stroke engine">Four-stroke</a></li> <li><a href="/wiki/Five-stroke_engine" title="Five-stroke engine">Five-stroke</a></li> <li><a href="/wiki/Six-stroke_engine" title="Six-stroke engine">Six-stroke</a></li> <li><a href="/wiki/Two-_and_four-stroke_engines" title="Two- and four-stroke engines">Two-and four-stroke</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Engine_configuration" title="Engine configuration">Cylinder layouts</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:10em"><a href="/wiki/Straight_engine" title="Straight engine">Inline / straight</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Single-cylinder_engine" title="Single-cylinder engine">I1</a></li> <li><a href="/wiki/Straight-twin_engine" title="Straight-twin engine">I2</a></li> <li><a href="/wiki/Straight-three_engine" title="Straight-three engine">I3</a></li> <li><a href="/wiki/Straight-four_engine" title="Straight-four engine">I4</a></li> <li><a href="/wiki/Straight-five_engine" title="Straight-five engine">I5</a></li> <li><a href="/wiki/Straight-six_engine" title="Straight-six engine">I6</a></li> <li><a href="/wiki/Straight-seven_engine" title="Straight-seven engine">I7</a></li> <li><a href="/wiki/Straight-eight_engine" title="Straight-eight engine">I8</a></li> <li><a href="/wiki/Straight-nine_engine" title="Straight-nine engine">I9</a></li> <li><a href="/wiki/Straight-twelve_engine" title="Straight-twelve engine">I12</a></li> <li><a href="/wiki/Straight-fourteen_engine" title="Straight-fourteen engine">I14</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:10em"><a class="mw-selflink selflink">Flat / boxer</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Flat-twin_engine" title="Flat-twin engine">F2</a></li> <li><a href="/wiki/Flat-four_engine" title="Flat-four engine">F4</a></li> <li><a href="/wiki/Flat-six_engine" title="Flat-six engine">F6</a></li> <li><a href="/wiki/Flat-eight_engine" title="Flat-eight engine">F8</a></li> <li><a href="/wiki/Flat-ten_engine" title="Flat-ten engine">F10</a></li> <li><a href="/wiki/Flat-twelve_engine" title="Flat-twelve engine">F12</a></li> <li><a href="/wiki/Flat-sixteen_engine" title="Flat-sixteen engine">F16</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:10em"><a href="/wiki/V_engine" title="V engine">V / Vee</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/V-twin_engine" title="V-twin engine">V2</a></li> <li><a href="/wiki/V3_engine" title="V3 engine">V3</a></li> <li><a href="/wiki/V4_engine" title="V4 engine">V4</a></li> <li><a href="/wiki/V5_engine" title="V5 engine">V5</a> <ul><li><a href="/wiki/VR5_engine" title="VR5 engine">VR5</a></li></ul></li> <li><a href="/wiki/V6_engine" title="V6 engine">V6</a> <ul><li><a href="/wiki/VR6_engine" title="VR6 engine">VR6</a></li></ul></li> <li><a href="/wiki/V8_engine" title="V8 engine">V8</a></li> <li><a href="/wiki/V10_engine" title="V10 engine">V10</a></li> <li><a href="/wiki/V12_engine" title="V12 engine">V12</a></li> <li><a href="/wiki/V14_engine" title="V14 engine">V14</a></li> <li><a href="/wiki/V16_engine" title="V16 engine">V16</a></li> <li><a href="/wiki/V18_engine" title="V18 engine">V18</a></li> <li><a href="/wiki/V20_engine" title="V20 engine">V20</a></li> <li><a href="/wiki/V24_engine" title="V24 engine">V24</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:10em"><a href="/wiki/W_engine" title="W engine">W</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/W_engine#W3_engines" title="W engine">W3</a></li> <li><a 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