Honda, renowned for being at the forefront of technological developments, has filed a patent for a VTEC system that it may incorporate into its flagship superbike – the Honda CBR1000RR, also known as the Fireblade.
What is VTEC?
Back in 1989, Honda engineer Ikuo Kajitani developed an ingenious way to make an engine more efficient and, at the same time, more powerful. The two are usually inversely proportional to each other, so let’s take a look at what it is and how it works.
If you’re here reading this, you probably know how an engine works. What you may not know, however, is that camshafts that have the best valve timing and lift for slow speeds and best fuel economy, aren’t great at going fast. That’s why cams in racing engines are big – they open and close the valves sooner, and hold them open for longer. This little extra time allows more air into the cylinders and, as a result, generates more power. However, the design used in these bigger cams is counterproductive at lower rpm, as they burn more fuel than required.
This is where variable valve timing (VVT) comes in. One of the most common forms of this is called cam phasing. In short, this method uses oil pressure or a stand-alone electronic unit, in addition to a cam phaser between the camshaft and its sprocket. This enables the engine to alter the rotational position of the camshaft in relation to that sprocket, varying the valve timing. This is the system Ducati uses on its DVT-equipped Multistrada and Diavel models.
However, the patent recently filed by Honda is slightly different. The camshaft here consists of two cam profiles for each valve. A smaller, smoother cam works at a lower rpm, and as the engine climbs higher up the rev band, an ECU enables the larger cam to actuate the corresponding valves. In this way, the engine performs optimally at both lower and higher rpm.
Honda introduced this technology as VTEC (Variable Valve Timing and Lift Electronic Control) in its cars, many of which have a huge fan following amongst enthusiasts. It soon brought similar tech that disengaged two valves at lower rpm onto the 1999 CB400SF Hyper road bike. Most motorcycles that sport VVT today, such as the Suzuki GSX-R1000, are equipped with the tech only affecting the intake valves. Honda’s patent is similar to that of BMW’s SwitchCam system seen on the 2019 R1250GS and S1000RR. What makes it stand out is the fact that Honda’s upcoming technology will alter both intake and exhaust valve timing, unlike BMW’s, which works only on the intake valves.
The current-gen Fireblade produces 189hp at 13,000rpm and a peak torque of 114Nm at 11,000rpm. Apart from a bump in power and stronger power delivery, the inclusion of VVT will also enable the bike to comply with stricter emission norms. We’ll have to wait and see what other updates the upcoming Fireblade will sport.
from Autocar India http://bit.ly/2H3YNXo
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