A hundred years ago, Opel launched its first four-valve per cylinder engine in the 1913 Grand Prix Car, paving the way for a series of four-valve engines that today are more present than ever in the brand’s lineup.
The three Grand Prix cars built featured a new four-cylinder engine with a displacement of 4.5 liters that produced 110hp and had two intake valves and two exhaust valves per cylinder. This was Opel’s first internal combustion engine with four valves per cylinder.
In 1914, the concept was developed into the 12.3-liter Opel Rennwagen, also known as the “Green Monster”. The gigantic engine had 4 valves per cylinder and produced 260 hp, propelling the 2,000-kg (4,409-lbs) race car to a maximum speed of 228 km/h (142 mph).
It wasn’t until the late 1950s, however, that engines with four valves per cylinder became fashionable again thanks to racing. The transition to production cars was slow though, with the first Opel series model to use this type of engine being the Opel Ascona 400 in 1979. A homologation special that allowed the brand to compete in the group 4 of rallying, the Ascona 400 featured a detuned 2.4-liter engine producing 140hp, 100 hp less than the rally car it was based on.
Despite that, it could still touch 200 km/h (124 mph) and accelerate to 100 km/h in 7.6 seconds. The golden era of the four-valve engines began in the 1980s, as manufacturers became aware of their lower fuel consumption and reduced emissions, not to mention the horsepower advantage.
Opel’s first volume-model to use a four-valve per cylinder engine was the Kadett GSi 16V in 1988. The Astra’s (outside the UK) predecessor featured a 2.0-liter 16V engine built with Cosworth that produced 150hp and 196 Nm (145 lb-ft) of torque, 90 percent of which was available between 3,100 and 6,000 rpm.
The same engine was also used in Formula 3 racing, where it helped Opel score 164 victories in Germany, and later formed the basis for the first Opel turbocharged gasoline engine, which debuted in 1991 in the Calibra Turbo 4×4 in which it produced 204hp.
Four-valve per cylinder engines spread across Opel’s range, including on the Omega and Senator in 1989 with the 3.0-liter 24V engine. This unit was the basis for the strongest Omega ever, the Lotus Omega (Lotus Carlton in the UK), which was powered by a 3.6-liter twin-turbocharged version of the engine developing 377hp.
In 1996, Opel was the first carmaker to combine the advantages of four-valve technology with diesel direct-injection and turbocharging on the Ecotec DI 16V diesel engines.
By Dan Mihalascu