Ilmor's 700cc five-stroke engine might possibly be used on a production motorcycle in the future!
Ilmor Engineering, the British company that came to MotoGP briefly in 2006 and 2007, has now developed a turbocharged, 700cc, three-cylinder, five-stroke petrol engine which might someday be used on a motorcycle.
A five-stroke engine? Yes indeed, Ilmor say this engine will deliver better fuel economy than a comparable diesel and is lighter and has lower emissions than a conventional four-stroke petrol engine of the same capacity.
How, exactly, does it work? Well, we don’t completely understand but we’ll quote from the Ilmor website. ‘The five-stroke concept engine utilises two fired cylinders (High Pressure - HP) operating on a conventional four-stroke cycle, which alternately exhaust into a central expansion cylinder (Low Pressure - LP), whereupon the burnt gases perform further work.’
‘The LP cylinder decouples the expansion and compression processes and enables the optimum expansion ratio to be selected independently of the compression ratio. Running of the concept engine has produced impressive fuel consumption readings over a very wide operating range. This is because at the onset of knock a greater percentage of work can be extracted in the LP cylinder, giving a degree of self compensation.’
All right, that reads like a physics textbook and we don’t understand most of it, but what’s really interesting is that Ilmor’s turbocharged 700cc five-stroke engine produces 130 horsepower at 7,000rpm and 166Nm of torque at 5,000rpm. And the best part is, according to Ilmor, the engine uses conventional technology and requires no new manufacturing techniques. This might allow the engine to be used on a production motorcycle sometime in the near future.
Ilmor claim their five-stroke engine has a power density of 150bhp/l and is 20% lighter than existing production engines of the same capacity. If the benefits really are as significant as the company claims, perhaps a mainstream motorcycle manufacturer will license this technology from Ilmor and use it on a production motorcycle. And wouldn’t that be cool…!