the eight-cylinder configuration. It was never raced with the four-cylinder engine. Swiss racing driver, engineer and fuel injection specialist Michael May transferred from Mercedes Benz to Porsche to work on the 753 engine, but wound up developing improvements for the 547/3 engine instead. May's changes included reducing the oil pressure, removing two of the engines five piston rings, using a new hardening process on the built-up Hirth crankshaft, narrowing the inlet ports, modifying the piston crowns and valve depth, using direct fuel injection, and adding a second non-drive fan impeller below the driven one. The cam profiles were unchanged. The modified engine, dubbed 547/3B, managed to produced a reliable at a time when May estimated that the 753 was producing just , the Ferrari 156 V6 engine and the Coventry-Climax and BRM V8s about . May felt that the 547/3B could win Formula One races, and showed Porsche's engineers that the 804 chassis could be modified to take the four-cylinder. He then struck an agreement with Ferry Porsche to have a 547/3B installed in a 718/2 that May would personally drive in practice at the 1962 Pau Grand Prix. When the car failed to arrive at Pau, May left Porsche for Ferrari. Only three 547/3B engines were ever built. With a compression ratio of 10.0:1, the 753 flat-eight engine produced at 9200 rpm on its first outing. This was still less power than the new Coventry-Climax and BRM V8 engines. With the improved six-speed transmission from the Type 718 and a ZF limited-slip differential, the car reached a top speed of . Technical summary Racing history The 804 debuted at the 1962 Dutch Grand Prix at Zandvoort on 20 May. This was also the debut race for the Lotus 25 monocoque chassis. The Porsche team was under instructions from Ferry Porsche that the cars should be returned to Stuttgart if they did not perform well in practice. Gurney started from eighth; Bonnier from thirteenth. Gurney managed to climb to third place but retired on lap ten after struggling with a broken shift linkage. Bonnier finished seventh, behind Carel Godin de Beaufort and his four-cylinder 718. Ferry Porsche was reluctant to commit to another race, reportedly ready to cancel the program at that point. Gurney spent time on the track tuning the car and personally convinced the chairman to field a single 804 for the 1962 Monaco Grand Prix on 3