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Ford Focus prototype with Torotrak variable drive supercharger (2017) review

CAR logo CAR 27/03/2017 CARMagazine
Ford Focus prototype with Torotrak variable drive supercharger (2017) review © Bauer Media 2017 Ford Focus prototype with Torotrak variable drive supercharger (2017) review

► Is this the supercharger of the future?

► We test 1.0-litre Ford Focus by Torotrak

► Three-cylinder engines puts out 148bhp

The downsizing of engines is here to stay – but that doesn’t mean it’s without its challenges. Chief among which is the quandary of how to extract the same power and performance of, say, a 1.5-litre engine, from a 1.0-litre engine. 

Torotrak, a high-tech engineering company, believes it has the answer. Namely, a variable drive mechanical supercharger (V-Charge) teamed with a conventional turbocharger. The former - essentially a supercharger with a Continuously Variable Transmission (CVT) sandwiched in the middle – provides the low-down oomph, while the latter – a regular turbo – provides the top-end pull. 

We reviewed a 256bhp 1.2-litre Mahle Golf GTI test mule not long ago which tackled the same problem, instead using an electrically driven compressor to provide the low-down go. So how does this mechanical alternative compare?

Ford Focus with Torotrak supercharger: the specs

This Torotrak test mule began life as a humble three-cylinder Ford Focus producing 123bhp and 148lb ft of torque from its 1.0-litre engine. With the addition of the V-Charge compressor – and a larger turbo – these figures are swollen to 148bhp and 181lb ft of torque. 

Not as punchy as the Mahle Golf GTI, perhaps, but then Torotrak points out that the car we drove wasn’t tuned for outright performance figures. Had it been more ambitious with the size of the turbo, engineers say they could have extracted far more power. 

How does the V-Charge work?

Unlike a regular supercharger, a small CVT is placed between the crankshaft pulley at one end and a compressor at the other end. This allows the supercharger to produce exactly the required boost at any engine speed, the upshot being no more lag at low engine rpm where the boost is needed most.

It’s within the mini-CVT itself where the magic happens. Put simply it contains two rollers clamped between an input disc and an output disc. By changing the angle of the rollers, Torotrak changes the transmission ratio. This changes the output speed of the CVT and the rotation speed of the compressor.

This differs from a conventional supercharger, where the supercharger speed is directly related to the engine speed. The obvious downside with this being that the supercharger can only operate at its most efficient over a small portion of the engine speed range. Outside of this range a conventional supercharger is thus wasting power and energy and requires a disconnect clutch.

Other advantages of the Torotrak technology, the company claims, include weight-saving (it’s considerably lighter than regular superchargers), refinement (the discs and rollers don’t actually touch, instead using traction fluid to transfer power) and its flexibility. The V-Charge can continuously deliver maximum boost regardless of whether the car has 12V or 48V architecture.

Enough of the theory, does the Torotrak supercharger work?

We tried the Focus with the technology switched on and off and could immediately tell the difference in real-world conditions. Accelerating onto a roundabout from low revs in second gear, the V Charge system gave the car a small, but noticeable, nudge forward followed by a confidence-inspiring surge of torque up to 3000 rpm. 

This nudge can, according to Torotrak, be programmed out, but we quite enjoyed the gentle reminder that the V Charge unit is doing its thing. It’s a subtle but effective improvement on the existing 1.0-litre EcoBoost engine, made all the more appealing by there being no noticeable effect on fuel economy. 

Our Torotrak co-driver also spoke of mischievous engineers attempting to fault the system, flooring the throttle from low revs in fifth gear. They did this once with the V Charge tech switched off and once with it on. With it deactivated, the car took over 45 seconds to get into its power band yet with the V Charge enabled, this was reduced to 10 seconds. 

We were impressed by the smoothness of the transition from V Charge torque to turbocharger power at around 3000 rpm. It's almost imperceptible and there’s an ironic hint of all-electric car powertrain in the way the Torotrak Focus smoothly gains speed. 

When can I buy it on my car?

This is the tricky bit. The technology is complete and ready for market, with Torotrak hoping to see it in mass production by 2022, such are the long lead times in the auto industry. However, manufacturers are becoming increasingly convinced that electric cars are the way forward - so it’s increasingly difficult to market a mechanical, combustion-based solution such as the one Torotrak is offering. 

Whether it’ll turn out to be a household name or a great bit of tech delivered too late, only time will tell.

More tech stories by CAR magazine


Price: £0

Engine: 999cc petrol 3-cylinder, 148bhp, 181lb ft @ 1400rpm

Transmission: Six-speed manual, front-wheel drive

Performance: n/a

Weight: 1280kg/steel

Dimensions: 4360/1823/1469mm


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