Yamaha Developing Turbocharged Twin

A patent application alone is no guarantee the machine it depicts will ever reach production but the existence of these patents showing a turbocharged Yamaha parallel twin prove that the firm has at least dedicated time and R&D resources to developing such a bike. Coming from the team of engineers that brought us the MT-09 (originally FZ-09 in the US market)—a machine that transformed the firm’s fortunes as a replacement for the underwhelming FZ8—the turbocharged designs are clearly cut from the same cloth.

But while the outlined bike resembles the three-cylinder, 847cc MT-09, delving deeper reveals that this design is actually based around a smaller, two-cylinder engine design. It’s not the 689cc parallel twin from the MT-07 though, appearing instead to be a version of the MT-09’s triple with one cylinder lopped off. That means its capacity would be around the 565cc mark, putting it very close to the 588cc, turbocharged Suzuki Recursion concept bike that was revealed back in 2013.

The patents themselves revolve more around the packaging of the turbocharger and the catalytic converter than other details of the bike. Two distinct layouts are shown, one more conventional than the other.

The first, conventional, design is very much like the Recursion in its layout. The exhaust headers from the two cylinders merge into one shortly after exiting the head, piping the gas into a turbocharger mounted low down in front of the cylinders. The catalytic converter is positioned under the front of the engine, and the compressed intake air from the turbo runs to an intercooler before being piped to the throttle bodies.

Yamaha’s first patent example has a fairly conventional design.

Japanese Patent Office

A second, more innovative layout is also shown, in which the turbo is mounted even closer to the exhaust outlets and inverted so its main body is level with the cylinder head. That means the catalytic converter can be mounted almost vertically ahead of the cylinders rather than underneath the engine. The benefit is that this layout would heat the catalyst faster, improving emissions performance on a cold start, and potentially give a packaging benefit.

Yamaha’s second design patent drawing shows the turbo inverted for tighter packaging and possibly quicker heating of the catalyzer.

Japanese Patent Office

In terms of performance, there’s no indication what Yamaha is aiming for. It’s known that Suzuki’s original 2013 Recursion concept was intended for improved fuel economy and emissions rather than out-and-out power, with a claimed 100 hp from a relatively low-revving, turbocharged engine. However, Suzuki’s own patents since then have revealed that the bike’s development has shifted toward a higher-performance design, with a DOHC twin replacing the original concept’s SOHC design and rumors of a capacity increase to nearer 700cc.

RELATED: Suzuki Turbo Twin Still Under Development

Yamaha’s design, based on the MT-09 engine’s architecture, also features a DOHC head, and it’s likely that by removing one cylinder and a third of the MT-09’s capacity and adding a turbo instead, the result would be a similar level of performance to the standard MT-09, while giving notable improvements in economy and emissions.

It’s worth noting that these patent applications mark the first evidence of recent interest in turbo technology from Yamaha. Its Japanese rivals have all been much more active in developing boosted bikes in recent years, with Kawasaki’s supercharged H2 models blazing the trail and Suzuki’s long-awaited Recursion-based production bike likely to be the first production motorcycle with an exhaust-driven turbo since the brief rash of Japanese turbo bikes in the mid-1980s.
More secretly, Suzuki has also filed patents showing turbocharged V-twin and inline four-cylinder motorcycle designs over the last few years. Honda, while remaining officially tight-lipped on turbo bike development, has also filed several turbobike patent applications, including turbocharged parallel twins based on the NC750 engine and turbocharged V-twin designs.

Why Turbos?

The renewed interest in turbocharging and supercharging over the last few years comes thanks to tightening emissions rules around the world, not just for bikes but also for cars. Forced-induction allows engineers to get more power from a smaller engine, giving better economy and emissions in the part-throttle conditions that bikes spend most of their time operating in.

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In the past, turbos have posed a problem when it comes to turbo lag—the delay between opening the throttle and getting boost—and parts availability. Today, modern electronics should be able to largely eliminate noticeable lag, and an explosion in the number of small-engined, turbocharged cars on the market means that turbo suppliers are much better-placed to offer bike-sized turbochargers than they were back in the 1980s when the Honda CB500 Turbo, Yamaha XJ650 Turbo, Suzuki XN85, and Kawasaki GPz750 Turbo failed to bring the technology to the fore.