Infiniti claims to have revolutionised the engine

Variable compression technology highlighted as the next big step in engine development.

NISSAN’S luxury arm Infiniti claims to have invented a revolutionary new petrol engine that consumes 27 percent less fuel yet can match the performance outputs of engines up to 50 percent larger.

Infiniti says this new Variable Compression Turbo (VC-T) engine technology is "a revolution in internal combustion engines" as significant as "liquid cooling, fuel injection and turbocharging. The arrival of variable compression ratio technology will establish new benchmarks".

The engine's ability to deliver significant fuel use savings and increased performance lies in its capacity to vary its compression ratio - the ratio at which fuel is mixed with air inside the cylinder.

A 2.0-litre, turbocharged four-cylinder petrol VC-T engine will be shown at the Paris Auto show in September. Infiniti claims this engine produces 200kW and 390Nm - equivalent to a conventional 3.0-litre V6, says Infiniti engineer Shinichi Kiga.

The VC-T engine is able to vary the amount of compression the air-to-fuel mixture undergoes between 8:1 and 14:1. A lower compression ratio is better for performance, while a higher ratio improves fuel efficiency.

Infiniti says the key to unlocking variable compression capabilities in a conventional internal combustion engine is a multi-link that was actually invented 20 years ago. It took until now for Infiniti's engineers to make it fit for production.

VC-T is not an easy system to put into words. Schematics below shown to Wheels at Infiniti's R&D centre in Atsugi near Tokyo in July show a harmonic drive and actuator connected to the multi-link, which in turn influences the piston's relative position inside the cylinder, and therefore the compression ratio.

Infiniti says the engine "makes an intelligent choice between performance and efficiency in all [driving] conditions", and can move "seamlessly between any compression ratio between 8:1 and 14:1".

Infiniti CEO Roland Krueger says the VC-T engine will be exclusive to Infiniti - and not shared with its Nissan or Renault alliance partners - initially, but he wouldn't put a timeframe on that exclusivity.

"We are utilising this engine first in Infiniti. We will also make sure it is marketed together with a new vehicle, an Infiniti. We will position this definitely as one of the leaders in the technology area. That is our goal, and our goal as a company."

The forthcoming Infiniti QX50 mid-size SUV is expected to be the first vehicle to market with this technology, and even though it's not due for launch until 2018, Infiniti is confident no other carmaker will beat it to market.

"Other manufacturers have taken the ‘VCR’ challenge, though Infiniti will be the first to bring the variable compression ratio engine to market from 2018," it said.