Opel 4-valve engines look back on 100-year tradition

The all-new turbocharged 1.6-liter gasoline and diesel engines which began the current renewal of Opel’s powertrain portfolio, and the compact 1.0 three-cylinder turbo that made its world premiere at the 2013 Frankfurt International Motor Show, are the latest in a long line of Opel engines with four valves per cylinder that stretches back 100 years. In 1913, Opel developed a new generation of racing cars for the Grand Prix de France, a forerunner of today’s formula one races. Opel produced three of these cars, each one built down to a rigorous weight limit of only 1000 kg. The real highlight, however, was under the hood, where an innovative new four-cylinder power unit provided the motive force. In addition to an aluminum crankcase and a single camshaft in the cylinder head, the 4.5-liter, 110 hp engine also featured two intake valves and two exhaust valves per cylinder – Opel’s first internal combustion engine with four valves per cylinder. From “Green Monster” to Ascona 400 Opel further developed the concept the following year, resulting in the most gigantic automobile the company has ever made – the 12.3-liter “Opel Rennwagen”, also known as “Das grüne Monster”, the “Green Monster”. The revised 12.3-liter 4-valve engine developed a huge 260 hp, capable of propelling the 2000-kg “Monster” to a maximum speed of 228 km/h! Opel works racing driver, Carl Joerns, scored most of his victories in this magnificent car, especially in beach races on the Danish island of Fanø. Four valves per cylinder went out of fashion throughout the automotive industry in the 1920s. They did not reappear until the late 1950s, in motor racing, and it was via rallying that Opel introduced the technology to its road cars in 1979. In order to compete in group 4, the top class of rallying at the time, with the Ascona 400, Opel had to produce a “road-going” model. While the rally-thoroughbred featured a newly developed, 177 kW (240 hp), 4-valve power unit, the homologation-special was equipped with a 140-hp version of the 2.4-liter engine. Despite this detuning, the “street-legal” Ascona 400 was still good enough for a maximum speed of 200 km/h and zero to 100 km/h-acceleration in 7.6 seconds. In the 1980s, four-valve engines became increasingly attractive, not only because of their inherent horsepower-advantage, but also because of their lower fuel consumption and reduced exhaust emissions. When Opel introduced the legendary Kadett GSi 16V in 1988, the brand’s first volume-model with four valves per cylinder, it immediately became an industry-icon. 2.0 16V – The engine to beat The technological highlight of the new high performance engine designed by Dr. Fritz Indra was its aluminum cylinder head developed in cooperation with Cosworth, the famous English racing engine builder. The sporty 2.0 16V produced 110 kW (150 hp) and maximum torque of 196 Nm at 4800 rpm. Ninety-percent of this torque was already available in a wide rev-band between 3100 and 6000 rpm. With its specific fuel consumption of 232 g/kWh, equivalent to an efficiency rating of 37 percent, the engine was a long-standing benchmark for specific fuel consumption in four-cylinder power units. The Opel 2.0 16V became the engine to beat in many other disciplines, too – in Formula 3 motor racing, for example, which produced so many future F1-stars like Michael Schumacher, Jarno Trulli, Nick Heidfeld and Alexander Wurz. During the classic era from the late 1990s through the mid-2000s, Opel F3 engines established themselves as the most successful in the world. Despite factory-supported competition from Alfa Romeo, Fiat, Mercedes-Benz, Toyota and VW, Opel scored 164 F3 victories in Germany alone, plus another 30 national championship titles around the world. Opel rapidly spread four-valves per cylinder to the rest of its powertrain portfolio. The company applied four-valve technology to the smooth-running, inline six-cylinder engine in its top-of-the-line models, Omega and Senator, in 1989. Four valves per cylinder + “Dual Ram” = Omega 3000 24V Thanks to the so-called “Dual Ram” induction system the engine was famous for its impressive power delivery at low revs. With 90 percent of the 270 Nm maximum torque available between 3000 and 5800 rpm, the Omega 3000 24V, for example, could accelerate from zero to 100 km/h in 7.6 seconds. By the way, the 3000 24V also provided the basis for the strongest Omega ever, the Lotus Omega, which was powered by a 3.6-liter, twin-turbocharged version of the engine developing 277 kW (377 hp). At the time, the Lotus Omega ranked just behind an extremely powerful Alpina limo as the fastest production-sedan in the world. The 2.0 16V from the Kadett GSi provided the basis for the first Opel turbocharged gasoline engine, which made its world premiere at the 1991 Frankfurt motor show in the Calibra Turbo 4x4. The 150 kW (204 hp) 2.0 16V turbo was notable not only for its high torque of 280 Nm at only 2400 rpm, but also the turbocharger and the exhaust manifold, which were integrated in a single component. The extremely low thermal losses of this integrated system significantly increased the efficiency of the turbocharger. Despite the 42-percent higher torque and 36-percent higher power-output of the 2.0 16V turbo compared with the naturally aspirated version, the average fuel consumption of both engines in the Calibra was almost the same – 8.9 versus 8.7 l/100 km. This tradition of high performance and high efficiency begun by the 2.0 16V in 1988 continues today with the new 1.6 ECOTEC Direct Injection Turbo gasoline engines. Opel’s reputation for innovative four-valve engines reached another peak in 1996 when the company became the first automobile manufacturer to combine the advantages of four-valve technology with diesel direct-injection and turbocharging. Direct-injection turbo diesels with patented valve-train The ECOTEC DI 16V diesels delivered high low-end torque, as well as low fuel consumption and emissions. The performance spectrum of the 2.0 and 2.2-liter engines stretched from 60 kW (82 hp) and 74 kW (100 hp) up to 88 kW (120 hp). They featured a patented valve-train operated by a single overhead camshaft. The introduction of the all-new, four-cylinder, 1.6-liter CDTI turbo family earlier this year demonstrates how Opel continues to play a leading role in diesel engine development. Featuring closed-loop combustion control and an aluminum block, the new 1.6 CDTI is the first diesel from Opel to comply with future Euro 6 emissions requirements, delivering climate friendliness, low fuel consumption, class-leading refinement, and high power/torque density. Drivers can look forward to more such benefits in the immediate future, as Opel continues its current product-offensive and long-standing tradition of technological innovation. By 2016, the Rüsselsheim manufacturer will have renewed 80 percent of its powertrain portfolio. Source: Opel