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Infiniti QX50 - Engineered Variable

Can one of the most technologically advanced production engines compel you to buy this Infiniti? We find out!

Date Published: 19 Feb 2019
Infiniti QX50 - Engineered Variable

Singapore - Inside the swanky looking new QX50 is a new breed of engine. On paper it sounds like what many of its competitors offer, a 2.0-litre turbocharged four banger but what goes on inside the Infiniti’s engine is unlike anything that has come before it.

Infiniti QX50 - Engineered Variable

Infiniti QX50 - Engineered Variable

The QX50 is the first ever production vehicle to have an engine than can change its compression ratio and its displacement when the need arises - a engineering feat which according to Infiniti has taken them over 20 years to perfect.

Infiniti QX50 - Engineered Variable

Infiniti QX50 - Engineered Variable

What’s the benefits you ask? Well, varying the compression ratio allows the engine to maximise its efficiency while its cruising part throttle or going flat-out on 1.5 bar of boost.

Infiniti calls it the VC-T engine short for Variable Compression, Turbocharged; as it can adjust how far its pistons rise in its cylinders on the fly, thereby changing the powerplant’s compression ratio, a parameter that has always been fixed since combustion engines were invented. The VC-T is able to toggle its compression ratio from as low as 8:0:1 to as high as 14:0:1.

Infiniti QX50 - Engineered Variable

Changing the engine’s stroke typically requires a new crankshaft but in the case of the Infiniti, the engine gets a joint between the crankshaft and con rods, which moves the joint via a computer-controlled arm.

Infiniti QX50 - Engineered Variable

Infiniti QX50 - Engineered Variable

During this process of changing how high the pistons move, the mechanism incidentally varies the stroke by 1.2mm, which also increases the engine’s displacement slightly from 1,971cc to 1,997cc. Stunned yet?

No car manufacturer has ever done this before on a production scale since adding extra bits to a high-stress and critical component like a crankshaft is like performing key-hole surgery with a binoculars and yet Infiniti has somehow perfected it.

Infiniti QX50 - Engineered Variable

Infiniti QX50 - Engineered Variable

The additional heavy-duty parts add weight though (about 10kg) to the moving parts of the engine, but the design shifts the crankshaft off-centre, smoothing out the piston’s motion.

Unlike most 2.0-litre four-cylinder engines, the QX50’s engine does not use balance shafts, this helps offset the weight of the new parts, to top that off, dynamic engine mounts keep out any unwanted vibrations from the cabin.

Now, given all that advanced engineering, the end-game would of course be significantly improved efficiency, so how good is the QX50’s fuel economy? On paper it states 12km/l, in reality I was averaging about 11.2-11.5km/l, which is pretty good considering my lead foot.

Infiniti QX50 - Engineered Variable

But (which is unfortunate), all this wouldn’t probably mean much to Infiniti’s target audience as opposed to a petrolhead. Luxury-minded owners are more likely to care about how the QX50 looks parked outside their driveway.

Its gorgeous in the flesh, its sheet metal showcasing aggressive creases and muscular lines, the front is dominated by a massive grille and pointy headlamps for added presence whilst the rear gets a distinction thanks to a lightning-like kink on the D-pillar, LED tail-lights and chunky contours for a futuristic finish.

Venturing into the cabin, Infiniti isn’t taking any risks, material quality is impressive with quilted leather seats, microsuede trim on the doors and centre console, the top half of the dash is clad in leather with contrasting stitching.

Infiniti QX50 - Engineered Variable

Infiniti QX50 - Engineered Variable

Infiniti QX50 - Engineered Variable

Infiniti QX50 - Engineered Variable

Infiniti QX50 - Engineered Variable

The centre stack features two touchscreens that split the work of the infotainment system, the upper display does the navigation that seems a tad backdated and clunky whilst the lower one features apps, audio control, smart phone pairing, vehicle settings and the navigation’s destination entry.

Infinity QX50 - Engineered Variable

Infinity QX50 - Engineered Variable

Infinity QX50 - Engineered Variable

Infinity QX50 - Engineered Variable

Thankfully climate controls have been given traditional buttons that flank the lower screen. That aside, the interior is spacious and airy, something the competition could learn a thing or two from Infiniti as the new platform makes it even wider than the Lexus RX350 with a rear bench that slides allowing for greater legroom as well than the longer Lexus.

Infiniti QX50 - Engineered Variable

Infiniti QX50 - Engineered Variable

Infiniti QX50 - Engineered Variable

Infiniti QX50 - Engineered Variable

Coupled with big and comfy front seats, the QX50 has more than enough space to seat four full-sized adults easily. Driving the QX50 is akin to how it looks, highly refined with fantastic manners.

Its transverse-engine layout gives it predictable dynamics - perfect for the lifestyle-orientated driver. Body control is tight and the car will always go where its pointed, though if you do point it harder the front tyres will give you a clear warning when they are reaching their limits.

The steer-by-wire system is still here in the QX50, in urban areas you only need minimal effort to get the Infiniti out of tight spaces and as you pile on the speed as the roads open up, the steering loads up linearly, its a wee bit artificial but I got used to it pretty quickly enough. The steering itself is quick and lively off-centre, so there’s no doubt the QX50 can be driven spiritedly if needed.

Infiniti QX50 - Engineered Variable

Off the lights, I detected a hint of turbo lag, which could be due to the CVT’s response but that VC-T engine under the bonnet packs a real punch once it goes into full swing as all 380Nm of torque come in from as low as 1,600rpm and its 268 ponies are unleashed at 5,600rpm.

Infiniti QX50 - Engineered Variable

Driven normally, there’s enough grunt to keep the CVT from having to spin past 3,000rpm, but if you do plant your foot to the metal, 0-100km/h is achieved in 8.3 seconds with a top speed of 230km/h.

Infiniti QX50 - Engineered Variable

Under normal conditions, you won’t be able to tell the engineering feat that is happening in the engine, it just feels and drive like any other force-induced in-line four. The only tell-tale sign is a digital meter labelled Power and Eco that appears in the centre of the speedo and tacho cluster showing you when the engine is in high or low-compression.

Infiniti QX50 - Engineered Variable

For those that push the QX50 harder, I did notice an interesting yet deeply satisfying throaty, almost Italian-like growl, as the engine approached its 6,000rpm redline; a delightful trait in an otherwise refined and very quiet crossover.

Another point to note, for those of you who like to keep the accelerator pedal embedded to the floor for long stretches, you would also notice how the CVT mimics gear shifts to keep the engine from spinning at a fixed high rpm whilst picking up speed, pull the paddle shifters and the CVT will offer you eight virtual gears. There are also four driving modes, Eco, Sport, Standard and a Personal mode that allows you to customise your own settings.

Infiniti QX50 - Engineered Variable

To answer our earlier question, will QX50 buyers buy the Infiniti for its impressive engine? Probably not. What would get their attention though is its fuel efficiency, highly refined cabin and overall good looks.

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  • Writer / Photographer Jackson Toh
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