Clean, smooth and quiet: Opel’s all-new three-cylinder will be celebrating its world premiere at the Frankfurt International Motor Show in September. The 1.0-liter turbo gasoline engine is not only climate-friendly, it also represents a new benchmark for refinement in three-cylinder engines, with noise and vibration characteristics superior to many four cylinder units.
Developing 85 kW/115 hp, this pocket powerhouse also delivers high low-end torque of 166 Nm all the way from 1,800 to 4,700 rpm, belying its diminutive size. The 1.0 SIDI Turbo (Spark Ignition Direct Injection) generates more torque throughout its operating range than equally powerful, higher displacement engines, while fuel efficiency is improved by 20 percent compared to Opel’s current 1.6-liter naturally aspirated power unit.
To be launched in the ADAM small car next year with an all-new six-speed gearbox, the 12-valve, 1.0 turbo is the first in a new, modular family of three and four-cylinder gasoline engines in the up to 1.6 liters class. State-of-the-art technologies such as direct injection, continuously variable valve timing, and a lightweight aluminium cylinder-block, are key efficiency enablers. Opel expects the new engine family to deliver impressive fuel economy and CO2 emissions significantly lower than 100 g/km.
“In developing this small engine, we not only set out to minimize fuel consumption and CO2 emissions, we also wanted to demonstrate that three cylinders can be just as refined as four or more,” says Dr. Matthias Alt, Opel’s Chief Engineer, Small Gasoline Engines. “We tackled at source the balance, noise and vibration issues typical of conventional three-cylinder engines, and we’re confident customers will be pleasantly surprised by the results. This is a very lively and refined three-cylinder engine which doesn’t compromise on driving fun.”
German engineering for class-leading acoustics
Opel engineers started with a clean sheet of paper, which enabled the incorporation of a series of measures to eliminate the typical, ‘off-beat’ running characteristics which have traditionally accompanied the economical driving appeal of three-cylinder engines.
The cylinder block made of high pressure die-cast aluminum is designed to reduce radiated and structure-borne engine noise, as well as reduce weight. The high-pressure fuel rail and injectors are also structurally isolated from the cylinder head to minimize the transmission of pulsing, while the fuel pump and fuel line are acoustically treated.
Another major contributor to refinement is the installation of a balance shaft in the oil sump. Driven by a chain with inverted teeth for quiet running, the counter-rotating shaft spins at crankshaft speed and is carefully mass-optimized to offset the inherent vibrations from a three cylinder operation.
Other noise attenuation measures include: acoustically-optimized covers for the top and front of the engine, the intake manifold and camshaft housings; crankshaft isolation with iron main bearing inserts; inverted teeth for camshaft drive chain; a low-hiss turbo compressor; and a lower oil pan in steel.
As a result of these engineering features, the new 1.0 SIDI Turbo is not only more refined than other three-cylinder engines, but also quieter than many four-cylinder units. For example, in bench testing at full throttle, it emits lower noise levels across all engine speeds than similarly powerful gasoline turbos with 1.6-liters displacement. Its inherent refinement is so good, that the need for additional in-car sound insulation, or complex engine mountings and sub-frames, is significantly reduced.
Strong power and torque
The 1.0 SIDI Turbo also packs a punch, generating more torque than Opel’s current 1.6-liter, naturally-aspirated engine, as well as the same 85 kW/115 hp maximum power output.
Jewel-like precision engineering is used in the integration of the exhaust manifold inside the aluminum cylinder head, which is bolted directly to the low-inertia, water-cooled turbocharger. This compact installation contributes to the delivery of a fast boost charge for strong, low-end power. Maximum torque of 166 Nm from just 1,800 rpm is almost 30 percent higher than the 1.6-liter engine generates at the same rpm.
The six-hole fuel injectors are centrally located above each piston to provide efficient combustion, and dual cam-phasing enables variable valve timing for optimum engine breathing. A twin displacement oil pump and a switchable water pump, which is disengaged when the engine coolant is cold in order to accelerate warm-up, also contribute to low fuel consumption.
All-new, weight-saving six-speed gearbox
The 1.0 SIDI Turbo is mated to an all-new, six-speed manual gearbox specially designed for medium torque applications. With a dry weight of only 37 kilograms, it is about 30 percent lighter than its current counterpart. It is also extremely compact, measuring just 375 mm along its axis.
Featuring superior shift quality, with a short lever travel and low shifting effort, the new transmission incorporates many of the refinements recently introduced on Opel’s next-generation gearboxes. These include gears with wide, asymmetrically-cut dog teeth, and triple-cone synchronizers for first/second gear, with double cones for third/fourth. Reverse gear is also synchronized.
The new gearbox will be used in a broad range of small and sub-compact Opel vehicles with engines rated at up to 220 Nm torque. For optimum powertrain efficiency in each application, the matrix of gearing choices comprises 12 sets of gear ratios and seven final drives.
Next step in Opel’s powertrain renewal program
The launch of the 1.0 SIDI Turbo and its new six-speed gearbox is the latest step in the renewal of Opel’s powertrain portfolio, which will see three new engine families and 13 new engines introduced between 2012 and 2016, plus a host of new transmissions.
The program began with the launch of the first engines in new mid-size gasoline and diesel families. These 1.6-liter turbo units are now joined by the 1.0 turbo, as the first example of a new, small displacement engine family. All will be built at GM’s new Szentgotthard plant in Hungary, where gasoline and diesel engines are produced on a shared assembly line.
New generation Opel power plants are focused on meeting a growing customer demand for ‘downsized’ engines which are able to deliver reduced fuel consumption and CO2 emissions, in combination with the power and refinement typical of larger displacement engines.