Infiniti delivers a new take on technology

Infinit Q60 sports coupe.

The upcoming QX50 crossover SUV will deliver the brand a technical breakthrough, becoming the first car in the world with variable-compression engine technology - the technology which could bring about the death of diesel engines in passenger cars. To be based around an all new four-cylinder engine, the variable-compression system is claimed by Infiniti to deliver V6 power with four-cylinder diesel fuel economy. It is said by Infiniti to achieve this by changing the engine's compression ratio depending on the power demand from the driver.

But the company isn't ignoring its more established technology, and this year it will also deliver a rear-drive Q60 coupe with a 300kW biturbo V6 powerplant. The new engine also underscores Infiniti's new family of S models, which will be the Japanese premium brand's high-performance family and the naming of which is bound to have Audi (which has S versions of the A3, the A4, the A6, the A8 and the A7, along with its Q3, Q5 and Q7 SUVs) fuming.

"There is a little red 'S' on the Q60 and you will find it going forward on all our performance vehicles," Infiniti boss Roland Krueger said.

The 300kW Q60 engine should also find its way into at least two other Infiniti models as well, and there is potential for either Nismo or Renaultsport, or both, to have input into an even hotter Infiniti using the revolutionary powerplant.

A bridging technology

The company is far from being the first car maker to try to use variable compression motors in production, with Porsche, Volvo, PSA (Peugeot-Citroen) and Renault all pushing ahead, viewing it as a bridging technology between internal combustion engines and electric cars.

The concept is effectively to change the swept volume of the engine's cylinders at top-dead centre, delivering the best of both worlds for performance and fuel consumption. It's also far from new, with British internal combustion engineering legend Sir Harry Ricardo inventing it in the 1920s. Technology of the day ruled out mass production, but Ricardo's invention led to his equally pioneering work in fuel quality, which delivered us today's octane rating system.

Saab's bankruptcy stopped it from delivering on the supercharged variable-compression four-cylinder petrol motor it debuted at the Geneva Motor Show in 2000. Very much a last addition to Saab's long list of quirky engineering innovations, its engine split the block into two halves, with what was effectively a hinge in the middle lifting one side of the block up to four degrees higher than the other.

There are other ideas for achieving the same result, though. Yamaha has worked with two-stroke variable- compression motors since the late 1990s, while Lotus's singlecylinder Omnivore concept used a movable puck at the top of the combustion chamber, Orbital fuel injection and a two-stroke cycle. Its development effectively stopped during the Dany Bahar era.

Peugeot has a concept dubbed MCE-5, which adjusts the connecting rod's length via a system that looks fearfully complex, while Dutch engineering outfit Gomecsys has a system it says that bolts on to existing crankshafts. One of the more promising and imaginative ways comes from Finland's Waulis Motors, with the crankshaft attached to an eccentric wheel, which is itself attached to a guidance wheel.

But Infiniti is staying mum on whether it's developing its own system or working with a concept that it has bought in from outside.

Source: Business Day