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.∎