Side view of an Italian <a href="https://en.wikipedia.org/wiki/en:Colombo_S.53" class="extiw" title="w:en:Colombo S.53">Colombo S.53</a> 1930s 4-cylinder inline engine at the <a href="https://en.wikipedia.org/wiki/en:Gianni_Caproni_Museum_of_Aeronautics" class="extiw" title="w:en:Gianni Caproni Museum of Aeronautics">Gianni Caproni Museum of Aeronautics</a>. Cut away for didactic purposes.
<a href="//commons.wikimedia.org/wiki/User:MLWatts" title="User:MLWatts">MLWatts</a>
<span class="int-own-work" lang="en">Own work</span>