Yamaha could be following Honda into the world of electronically assisted turbo motorcycles, as these patents reveal.
Patents filed by Yamaha show that the Iwata factory is considering the use of electronic turbo (E-turbo) systems, with a potential new motorcycle equipped with a CP3 engine on the way.
Honda made waves at EICMA last year when it presented its V3 concept, an innovative configuration with an even more interesting aspiration system. Instead of conventional turbo or supercharging, the Honda V3 used an electronically driven turbo – and Honda may not be alone in thinking about utilising it.
The new patent from Yamaha shows a naked motorcycle, with a profile similar to one of the company’s CP3-powered machines. Not many technical details are revealed, with the images showing where and how the system will be integrated into the motorcycle and how the intakes, manifolds and power systems will be positioned.
Why are manufacturers considering E-turbos over conventional methods?
The shift to E-turbos is partially driven by increasingly stringent emissions regulations. With ever more restrictive rules that manufacturers must comply with, extracting 1,000cc performance from much smaller capacity engines is a very sensible approach.
And while you may be thinking, “well why not just use a normal turbo?” Conventional turbos fitted to motorcycles bring their own technical problems. For starters, space is at a premium on a motorcycle, much more so than in the automotive industry. Turning to an E-turbo means you can, within reason, position the operational part of the system in a location optimised to make the most of the motorcycle’s svelte packaging.
Conventional turbos, which are most commonly driven by exhaust gases from the engine, also have two other disadvantages. Heat and lag. Driven by exhaust gases, turbos can reach temperatures exceeding 1,000 degrees celsius, and so much heat being emitted from a component, on something as small as a motorcycle, can have major knock-on effects. Exhaust-driven turbos also suffer from something called turbo lag, which is a situation where the turbo will only give full power once the turbine in the turbo is up to speed – or ‘spooled-up’ if we are using colloquial terminology. Think of turbo lag a bit like riding a small capacity high-performance two-stroke motorcycle. At the bottom of the rev range you have practically no power or torque, although it all arrives at once when the engine hits the sweet spot. Turbo lag is a bit like that – when spinning slowly, the turbo isn’t pressurising the inlet gas enough to make a difference. But once it gets up to speed, all the power arrives in one big lump.
So if there are so many problems, why not supercharge, like the Kawasaki H2?
Superchargers then seem like an ideal compromise, although they also have their drawbacks, with an increase in the amount of heat created being one of the biggest. Supercharging also brings with it its own set of packaging problems, and if it’s driven via the engine’s crankshaft, as is common, manufacturers may only have a few places where it could be fitted.
Crucially (and this is at the heart of the interest in E-turbos), both superchargers and turbos cannot be used on demand. E-turbos can. If motorcycle manufacturers want to boost the engine with more power and torque only in a very specific rev window, the E-turbo can be switched on to help bridge the performance gap. Indeed, an E-turbo could even be mapped for specific riding modes and even gear ratios, boosting engine performance for more torque in the lower gears, and optimising it for top-end power in the higher gears. E-turbos offer motorcycle manufacturers a level of adaptability that a wholly mechanical system simply cannot match.
