Editing Wankel engine (section)

===Compression-ignition Wankel===
{{Main article|Wankel Diesel engine}}

[[File:Two Stage Rotary RR R1C.jpg|thumb|'''Figure 16.'''<br/>Rolls-Royce R1C compression ignition prototype]]

Research has occurred into rotary compression ignition engines. The basic design parameters of the Wankel engine preclude obtaining a compression ratio sufficient for Diesel operation in a practical engine.<ref name="Eichlseder Klüting Piock 2008 p. 222">{{cite book |last1=Eichlseder |first1=Helmut |last2=Klüting |first2=Manfred |last3=Piock |first3=Walter F. |title=Grundlagen und Technologien des Ottomotors |place=Wien |date=2008 |isbn=978-3-211-25774-6 |oclc=255415808 |language=de |page=222}}</ref> The Rolls-Royce<ref name="zqxX7">''Autocar'' magazine, week ending Dec 17, 1970</ref> and Yanmar compression-ignition<ref name="tqVfR">SAE paper 870449</ref> approach was to use a two-stage unit (see figure 16.), with one rotor acting as compressor, while combustion takes place in the other.<ref name="LfWIG">Wolf-Dieter Bensinger: Rotationskolben-Verbrennungsmotoren, Springer, Berlin/Heidelberg/New York 1973, {{ISBN|978-3-642-52174-4}}. p. 141</ref> Both engines were not functional.<ref name="Eichlseder Klüting Piock 2008 p. 222"/>