Monday 17 February 2014

Opel/Vauxhall gives Adam a three-cylinder

Adam is the first car in the OpelVauxhall range to receive the new, all-aluminium three-cylinder 1-litre Ecotech direct injection turbocharged gasoline engine developed at the company’s International Technical Development Centre.

The engine comes in two power outputs: 90PS and 115PS. Both ratings deliver low-end torque of 166Nm from 1,800rev/min. Like the two new generation 1.6-litre mid-size units the company has launched recently, the1.6 Ecotech direct injection turbocharged gasoline engine and the 1.6 CDTi ‘Whisper Diesel’, the new 1-litre Ecotech is said offer “benchmark refinement with outstandingly low noise, vibration and harshness”.

The engine will be launched at next month’s Geneva Motor Show.

With start/stop functionality as standard, the 90PS version gives Adam combined cycle fuel consumption as of 62mile/gal, with CO2 emissions of 99g/km, according to preliminary data. Efficiency enablers include direct fuel injection, variable valve timing, weight-saving all-aluminium construction and a switchable water pump.

The first in a completely new family of small displacement petrol engines, the 12-valve 1-litre Ecotech is the next step in Vauxhall’s powertrain offensive following the recent introduction of new 1.6-litre mid-size petrol and diesel engine families.

These three new powertrains share a common DNA and development target: to be the most refined in their respective categories. Starting with a clean sheet of paper, Opel/Vauxhall engineers focused on eliminating ‘off-beat’ running characteristics which traditionally detract from the economical driving appeal of three-cylinder engines.

“We not only set out to minimise 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/Vauxhall’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 Adam customers will be enthusiastic about the results.”

The cylinder block, in high pressure die-cast aluminium, 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 minimise the transmission of pulsing, while both the fuel pump and fuel line are acoustically treated.

A further contributor to running refinement is a balance shaft in the oil sump. Driven by a chain with inverted teeth for quiet running, it counter-rotates at crankshaft speed and is mass-optimised to offset the inherent vibrations of a three cylinder operation.

Other noise attenuation measures include: acoustically-optimised 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 chains; a low-hiss turbo charger, and a lower oil pan in steel.

Opel/Vauxhall claims that with its ‘sound engineering’ features, the new 1-litre Ecotech is “not only more refined than other three-cylinder engines, it’s 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 naturally-aspirated engines of 1.6-litre displacement.

The exhaust manifold is housed in the aluminium cylinder head, to which the tiny, low-inertia, water-cooled turbocharger is directly bolted.

The six-vent fuel injectors in the direct injection system are centrally located above each piston to provide efficient combustion, and dual cam-phasing enables variable valve timing to optimise 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.

                                     Lightweight gearbox

The 1-litre engine is mated to a new generation six-speed manual transmission. Of compact design and a dry weight of 37kg, it is 30 per cent lighter than units it replaces.

The transmission has wide, asymmetrically-cut dog teeth and triple-cone synchronisers for first/second gear, with double cones for third/fourth. Reverse gear is also synchronised.

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