Editing Wankel engine (section)

===NSU and Mazda===
Mazda and NSU signed a study contract to develop the Wankel engine in 1961 and competed to bring the first Wankel-powered automobile to the market. Although Mazda produced an [[Mazda Wankel engine|experimental rotary]] that year, NSU was the first with a rotary automobile for sale, the sporty [[NSU Spider]] in 1964; Mazda countered with a display of two- and four-rotor rotary engines at that year's [[Tokyo Motor Show]].<ref name="JhYt4Sa"/> In 1967, NSU began production of a rotary-engined luxury car, the [[NSU Ro 80|Ro 80]].<ref name="ndjUi">{{cite magazine |url= http://www.time.com/time/magazine/article/0,9171,899809,00.html |archive-url= https://web.archive.org/web/20081215132322/http://www.time.com/time/magazine/article/0,9171,899809,00.html |url-status= dead |archive-date=December 15, 2008 |title=The Wankel Wager |magazine=Time |date=1967-09-08 |access-date=2011-12-11}}</ref> NSU had not produced reliable apex seals on the rotor, though, unlike Mazda and Curtiss-Wright. NSU had problems with apex seals' wear, poor shaft lubrication, and poor fuel economy, leading to frequent engine failures, not solved until 1972, which led to large warranty costs curtailing further NSU rotary engine development. This premature release of the new rotary engine gave a poor reputation for all makes, and even when these issues were solved in the last engines produced by NSU in the second half of the '70s, sales did not recover.<ref name="JhYt4Sa"/>

By early 1978, Audi engineers Richard van Basshuysen and Gottlieb Wilmers had designed a new generation of the Audi NSU Wankel engine, the KKM 871. It was a two-rotor unit with a chamber volume V<sub>k</sub> of 746.6&nbsp;cm<sup>3</sup>, derived from an eccentricity of 17&nbsp;mm, a generating radius of 118.5&nbsp;mm, and equidistance of 4&nbsp;mm and a housing width of 69&nbsp;mm. It had double side intake ports, and a peripheral exhaust port; it was fitted with a continuously injecting [[Bosch K-Jetronic]] multipoint [[manifold injection]] system. According to the DIN 70020 standard, it produced 121&nbsp;kW at 6500 rpm, and could provide a max. torque of 210&nbsp;N·m at 3500 rpm.<ref name="Van Basshuysen Wilmers 1978 p. 3"/> Van Basshuysen and Wilmers designed the engine with either a thermal reactor, or a catalytic converter for emissions control.<ref name="Van Basshuysen Wilmers 1978 p. 3">{{cite conference |last1=Van Basshuysen |first1=Richard |last2=Wilmers |first2=Gottlieb |title=SAE Technical Paper Series |chapter=An Update of the Development on the New Audi NSU Rotary Engine Generation |publisher=SAE International |date=1978-02-01 |volume=1 |issn=0148-7191 |doi=10.4271/780418 |page=3}}</ref> The engine had a mass of 142&nbsp;kg,<ref name="Van Basshuysen Wilmers 1978 p. 3"/> and a BSFC of approximately 315&nbsp;g/(kW·h) at 3000 rpm and a BMEP of 900&nbsp;kPa.<ref name="Van Basshuysen Wilmers 1978 p. 11">{{cite conference |last1=Van Basshuysen |first1=Richard |last2=Wilmers |first2=Gottlieb |title=SAE Technical Paper Series |chapter=An Update of the Development on the New Audi NSU Rotary Engine Generation |publisher=SAE International |date=1978-02-01 |volume=1 |issn=0148-7191 |doi=10.4271/780418 |page=11}}</ref> For testing, two KKM&nbsp;871 engines were installed in [[Audi 100#Audi 100, 200 and 5000 (C2, 1976–1982)|Audi 100 Type 43]] test cars, one with a five-speed manual gearbox, and one with a three-speed automatic gearbox.<ref name="Van Basshuysen Wilmers 1978 p. 16">{{cite conference |last1=Van Basshuysen |first1=Richard |last2=Wilmers |first2=Gottlieb |title=SAE Technical Paper Series |chapter=An Update of the Development on the New Audi NSU Rotary Engine Generation |publisher=SAE International |date=1978-02-01 |volume=1 |issn=0148-7191 |doi=10.4271/780418 |page=16}}</ref>