Porsche flat-eight engines

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Porsche built several flat-eight engines of different sizes over many years, mainly for racing. The first was the Type 753, created starting in 1960 after a 1.5-liter F1 limit was announced. It kept Porsche’s boxer, air‑cooled design but added eight cylinders. Its bore and stroke were 66.0 mm by 54.6 mm for about 1.494 L displacement. The engine used a magnesium crankcase, separate heads for each cylinder, and a sophisticated valvetrain with two overhead camshafts per bank, driven by shafts. It featured two countershafts, a dry sump, Bosch ignition, and four 38 mm Weber carburetors. Early power was around 105–120 hp, well short of the target, so Mezger and team improved reliability and output by reducing the valve angle, lightening parts, and using titanium rods, eventually reaching about 185 hp.

The Type 753 made its race debut in the Type 804 at the 1962 Dutch Grand Prix, producing about 177 hp at 9,200 rpm. With improved gearing and a strong chassis, the 804 could reach around 270 km/h, and Porsche scored its only F1 win as a constructor with the 753-powered 804 driven by Dan Gurney at the 1962 French Grand Prix. A shorter-stroke version appeared as 753/1. A second flat-eight, the Type 771, was aimed at 2.0 L sports cars and displaced about 1,982 cc, producing around 240 hp. It powered models such as the 718, 904, 906, 910, 907 and 909 Bergspyder, with a 2.2 L variant (771/1) later developed. The 908 family then emerged by adapting the 916 V6 with two extra cylinders, producing the Type 908 engine. Bore and stroke were 84 by 66 mm for about 2,926 cc, initially delivering around 320 hp and debuting in 1968. The 908 powered the factory VW-Porsche 914/8 race cars built in 1969, with one 914/8 delivering 298 hp and another detuned to 261 hp for Ferry Porsche.

Beyond these racing engines, Porsche worked on a broader internal project known as Type 1966, tied to Volkswagen’s EA266 Beetle replacement. The plan envisioned a three‑tier family of water‑cooled boxer engines (four-, eight-, and twelve‑cylinder) with DOHC heads. A prototype eight‑cylinder was built, but after the project was canceled, materials and the prototype were reportedly destroyed.

In the 2010s there were rumors of another flat‑eight from Porsche, linked to a mid‑engined project initially called 988 and later the 960. This proposed 4.0 L engine would use four turbochargers and was said to push power beyond 600 hp, with release dates suggested for 2019 or as late as 2026.