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Infiniti, a brand with all the visibility of the tooth fairy but none of the fame, has achieved one of the Holy Grails of engine technology, unveiling the world’s first production-ready variable compression ratio engine in its new mid-size SUV, the QX50.
By switching its compression ratio from a performance-friendly 8:1 ratio to a highly efficient 14:1, through the use of an ingenious multi-link system that continuously raises and lowers the pistons’ reach, the VC-Turbo 2.0-litre engine combines the power of a turbocharged petrol engine with the torque and efficiency of a four-cylinder diesel.
The new engine, which will arrive late in 2018 in the QX50 - a genuinely attractive mid-size SUV designed to take on the likes of BMW’s X3 and the Audi Q5 - makes 200kW/380Nm, and offers a 35 per cent improvement in efficiency over the previous model (which was not sold in Australia), at 9.0L/100km.
Infiniti also claims the new VC Turbo is as smooth, and quiet, as bigger V6 units, thanks to the fact that it does away with the two balance shafts required in conventional four-cylinder engines.
Speaking at the car’s launch in Los Angeles, the night before the LA Auto Show, Infiniti’s global vice president for marketing and sales, Christian Meunier, described the new QX50 as “the most important vehicle we’ve ever launched” and said the engine technology was the result of almost 20 years of hard work by Infiniti and Nissan engineers (Infiniti is to Nissan what Lexus is to Toyota, in case you didn’t know).
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“This car combines the power and strength of a sprinter with the efficiency and endurance of a marathon runner,” Meunier added.
“This engine transforms on demand, setting a new benchmark for powertrain capability and refinement.”
The system works by using a world first multi-link system combined with an electric motor and a 'Harmonic Drive' reduction gear to transform its compression ratio. The electric motor connects to the Harmonic Drive with a control arm and as the Harmonic Drive rotates, the control shaft at the base of the engine rotates, moving the multi-link system.
This allows the system to change the top dead-centre position of the pistons, and thus the compression ratio. Effectively, the engine capacity varies between 1997cc (at an 8:1 ratio) and 1970cc (14:1).
Could the QX50 be the car that finally gains Infiniti some attention in Australia? We’ll have to wait until next year to find out, and Infiniti Australia is not releasing any pricing information as yet.
