none of these were very successful. For their YZ250F and YZ450F motocross bikes, Yamaha developed five-valve engines. Bugatti (EB 110), Ferrari (F355, 360 and F50), Volkswagen - Audi (Audi Quattro) - Skoda (Octavia vRS) and Toyota (4A-GE 20V) have all produced five-valve-engined vehicles. Six valves In 1985, Maserati made an experimental 2.0-liter turbo V6 engine with six valves per cylinder (three intakes, three exhaust). It achieved at 7,200 rpm (97.5 kW/liter). Pushrod Although most multi-valve engines have overhead camshafts, either SOHC or DOHC, a multivalve engine may be a pushrod overhead valve engine (OHV) design. GM has revealed a three-valve version of its Generation IV V8 which uses pushrods to actuate forked rockers, and all Duramax V8 engines have four valves per cylinder with pushrods. Moreover, Cummins makes a four-valve OHV straight six diesel, the Cummins B Series (now known as ISB). Ford also uses pushrods in its 6.7L Power Stroke engine using four pushrods, four rockers and four valves per cylinder. The 6.0 and 6.4 Powerstroke engine built by Navistar also used pushrods with four-valve heads. Pushrod multi-valve systems are common on diesels because they need to be able to meet emissions standards, but also produce more low-end torque. The Harley-Davidson Milwaukee Eight engine, introduced in 2016, uses four-valves per cylinder driven by pushrods and a single in-block camshaft. Turbocharged The 1980 Lotus Essex Turbo Esprit (with type 910 2.2-liter inline four engine) was the first production car to use a multi-valve turbocharged engine. Motorcycles Examples of motorcycles with multivalve-engines include: 1914 Peugeot Grand Prix racer, 500 cc DOHC 8-valve parallel twin (top speed over 122 km/h). 1915 Indian board track racer, 61-cid (1.0-liter) OHV 8-valve V-twin. 1921 Triumph Ricardo 499 cc OHV 4-valve single-cylinder machine, copied by Rudge-Whitworth with their 1924 Rudge Four 350 cc OHV 4-valve single-cylinder machine, and 1929 Rudge Ulster 500 cc OHV 4-valve single-cylinder machine. 1923 British Anzani 1098cc OHV 8-Valve V-twin, used in Morgan three-wheelers and McEvoy motorcycles 1972 Honda XL250 "pent-roof" SOHC 4-valve single-cylinder machine (the first mass-produced 4-valve motorcycle). 1973 Yamaha TX500 "pent-roof" 500cc DOHC 8-valve parallel-twin (the first mass-produced DOHC 4-valve per cylinder motorcycle) 1977 Honda CB400 SOHC 6-valve parallel-twin. 1978 Honda CX500, a 498 cc SOHC, pushrod actuated OHV, 4-valve per cylinder V-twin; 1982 CX500 Turbo was the first factory multi-valve turbocharged motorcycle. 1978 Honda CBX1000, a 1,047 cc DOHC 24-valve straight-6 (). 1979 -1992: Honda NR series, racing