Winnipeg Free Press

New Infiniti turbo delivers fuel economy breakthrough

by Kelly Taylor . Dec 22 2017
InfinitiThe 2019 QX50 is the first production vehicle to offer a variable compression turbo engine.


The 2019 QX50 is the first production vehicle to offer a variable compression turbo engine.

LOS ANGELES — It’s a technology automotive engineers have been dreaming about for 80 years.

Last week in Los Angeles, Infiniti made it happen.

It’s long been known that you could improve efficiency of a gasoline engine if you could vary the compression ratio: high compression for efficiency, low compression for power.

Many have tried, many have failed.

The 2019 QX50, unveiled last week, is billed as the first production vehicle to offer a variable compression turbo engine (VC-T).

Essentially, what it does is change the angle with which the connecting rod meets the crankshaft. This change in angle changes how far the piston travels inside the cylinder.

According to Infiniti, the technology means the 2.0-litre turbo achieves a 30 per cent gain in fuel economy over the QX50’s predecessor V-6 engine. It estimates it will peg combined fuel consumption at 9.1 litres per 100 kilometres for all-wheel-drive versions, all while providing peak horsepower of 268 and torque of 280 lb-ft.

The engine is mated to an Xtronic continuously variable transmission and, for Canada, is offered only with all-wheel drive. Also unique to Canada, it comes standard with heated seats and a heated steering wheel.

The engine is touted as a game-changer, potentially extending the life of the internal combustion gasoline engine, said Infiniti powertrain engineer Christopher Day. It offers the efficiency of a four-cylinder non-turbo engine with the torque of an advanced four-cylinder diesel engine.

“This is a complete breakthrough, since we’ve been trying to do it for 20 years, and not just us — the industry has been trying to do this for 80 years,” Day said as media milled around the new engine.

Typically, a connecting rod and the top half of the bearing journal — which connects the rod to the crankshaft — are one piece, with the centre of the rod centred on the attachment to the crankshaft. In the VC-T, the rod connects to a bearing on one side of the bearing journal, while another rod connects to the other side. That rod is connected to another shaft that rotates when required to vary the compression. The result is a change in how the connecting rod and crankshaft relate, which in turn changes how much the piston can travel inside the cylinder.

The change in compression means the engine can get more power at low compression, when the risk of pre-detonation — pinging — is lower, and switch to high compression for efficiency, which lets the control unit inject less fuel.

The other big news for QX50 is the implementation, as standard equipment, of Nissan’s ProPilot Assist technology. As the name implies, it’s a driver assistance package, and represents only one step toward autonomous driving.

ProPilot Assist will help in maintaining speed, will actively maintain lane control and provides warnings, and braking, if needed, when it detects potential collisions.

But it will not let you divert your attention from driving, at least not for long. If it detects you aren’t holding the wheel, it will offer increasingly prominent warnings before finally bringing the car slowly to a stop and activating the flashers, thinking such a level of inattention can only mean one thing — the driver is incapacitated.

Nissan Canada president Joni Paiva said such is an indication of Nissan’s intention as it gets closer to its goal of autonomous vehicles.

“I want to give control of the car to the car,” he said, “But I want to be the one giving up control.”

In other words, look for future autonomous vehicles from Nissan to continue to offer drivers the option of driving. Paiva said drivers who enjoy an exciting, twisty road will continue to do so, but will have the option of handing over control during boring, stop-and-go driving or boring stretches on straight highways.

For now, however, ProPilot Assist is just as the name implies: you can’t set it and then zone out.

The QX50 gets a complete redesign for 2019, including a prominent and more vertical front fascia; the large, trapezoid grille as well as a roofline that extends further back to a spoiler dropping more sharply at the rear. The D-pillar also gets Infiniti’s signature crescent-cut design, something the outgoing QX50 didn’t get.

The interior is redesigned, as well. Instead of the outgoing model’s combined centre stack and centre console, the centre stack and large infotainment screen are broken by a continuation of the upholstery covering the area above the glove box.

The large, prominent knob from the predecessor’s user interface is gone, replaced by a smaller knob near the climate controls. More touch-screen commands are offered, but key ones are brought out to actual controls, too.

One thing that may give some drivers pause is the new QX50 not only offers drive-by-wire for throttle control, it’s also drive-by-wire for steering. Under normal circumstances, no direct mechanical link exists between steering wheel and steering rack. Instead, the steering wheel activates a sensor that then directs motors on the steering rack to turn the wheels.

It debuted on the Q50 sedan, and it allows drivers to tailor the steering response to conditions, from a super-sharp response that takes a full turn out of the steering wheel’s lock-to-lock rotation to a traditional response that is the more typical 2.5 turns lock-to-lock.

In the event of a power or system failure, a clutch engages a direct mechanical link in the steering column as a backup.

The QX50 is expected in showrooms in the summer of 2018.