It’s been over 6 months since Honda released patented drawings of the Supercharged NC750. Is it still on the cards? Time will tell.
No doubt Honda adventure bike enthusiasts have been eagerly awaiting the release of the rumored Supercharged NC750, to some it may seem a little strange, a supercharger on the humble NC750, but hey, why not, certainly nothing strange about it for adventure riders. When looking closely at the layout specified in the patent drawings it looks like the supercharger has been part of the plan since day 1, the questions is when.
Looking at the layout shown in Honda’s patent drawings based around the NC750 parallel twin, it seems likely that supercharging has been in the firm’s plan ever since the NC750 was first mooted.
The near-horizontal cylinders, which allow for a large luggage space under the dummy fuel tank on the normal NC750S and NC750X, mean there’s plenty of room to sit a crankshaft-driven supercharger and all its related pipe work on top of the engine. While that eliminates the storage space, it means the bike isn’t compromised elsewhere.
Importantly, there’s even space for a large intercooler, which Kawasaki’s H2 lacks. Intercoolers are useful on any forced-induction engine because the act of compressing the intake air also creates a lot of heat. Hot intake air is less dense than cold air, harming performance. With an intercooler, boost can safely be increased.
On the Honda designs, which were drawn up before the Kawasaki H2 appeared, the supercharger is mounted in a similar position to the Kawasaki’s, just behind the cylinders. It takes air from an airbox between the rider’s legs, compresses it and feeds it forwards into an air-to-air intercooler under the front of the dummy fuel tank.
As on the normal NC750, the real fuel tank is under the seat. The intercooler is effectively a radiator, but instead of water it’s the intake air that runs through it. Cold air, coming in through an intake on the front of the bike, runs over the intercooler’s fins, drawing heat away.
After it’s been cooled, the compressed intake air is rushed into a plenum chamber, which is a pressurised storage tank that removes pressure waves and surges from the air and means there’s always a supply of compressed air ready when the throttle is opened.
The plenum chamber has two outlets: the main one feeds into the engine’s throttle body, where fuel is added before it reaches the cylinders, while a second outlet is fitted with an electronically-controlled bypass valve so if the pressure in the chamber gets too high, the engine management system can release some air from the system. Cleverly, the released air goes back into the supercharger rather than simply being vented.
Just how much performance the supercharger will add is going to be largely down to the way it’s set up. However, it’s easy to imagine that it could double the stock NC750’s power, making it a 100bhp machine that would still retain most of the normally-aspirated version’s astonishing fuel economy and low emissions.
Given that the first patents relating to Kawasaki’s H2 appeared nearly four years ago, we could still face quite a wait before seeing the fruits of Honda’s labours in showrooms.
Image Credits: 1, 2