|The new 1.0L turbo. Click to enlarge.|
Opel will introduce the first in an all-new modular family of small-displacement three- and four-cylinder gasoline direct injection engines at the upcoming Frankfurt International Motor Show next month. The new three-cylinder 85 kW/115 hp, 1.0-liter turbo will be launched in the Opel Adam, coupled with an all-new six-speed gearbox.
The engine produces low-end torque of 166 N·m (122 lb-ft) all the way from 1,800 to 4,700 rpm. The 12-valve 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% compared to Opel’s current 1.6-liter naturally aspirated power unit.
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 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. 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.—Dr. Matthias Alt, Opel’s Chief Engineer, Small Gasoline Engines
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.
|The exhaust manifold is integrated inside the aluminum cylinder head, which is bolted directly to the low-inertia, water-cooled turbocharger. Click to enlarge.|
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.
In bench testing at full throttle, the new engine emits lower noise levels across all engine speeds than similarly powerful gasoline turbos with 1.6-liter displacements. With its inherent refinement, the need for additional in-car sound insulation, or complex engine mountings and sub-frames, is reduced.
The exhaust manifold is integrated 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. The maximum torque of 166 N·m is almost 30% 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.
|New 6-speed gearbox. Click to enlarge.|
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 (82 lb), it is about 30% 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 N·m (162 lb-ft) torque. For optimum powertrain efficiency in each application, the matrix of gearing choices comprises 12 sets of gear ratios and seven final drives.
Opel plans to introduce three new engine families and 13 new engines between 2012 and 2016, plus a number 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.