A good scooter engine needs the following characteristics:
Those characteristics are in line (mostly) with the specification of a modern two-stroke engine. However, the non-stop upward spiral of anti-pollution laws has imposed new limits to scooter engines.
Three immediate solutions are capable of operating in today's legislative environment:
High speed four stroke engine (with or without catalyst / secondary air injection);
Two stroke catalyzed engine (with or without secondary air injection);
Two stroke engine with direct injection (the most revolutionary solution).
Aprilia has decided to follow the third way by presenting DITECH, a new perspective in the motorcycling world.
Obviously, as pioneer of this technology on small, high-speed engines, Aprilia has spent a great deal of time and money to solve the “application” related problems of the DITECH system, problems not previously encountered.
The biggest design and /or development challenges during the engine's industrialization have been:
Air compressor lay-out / Crank shaft balancing;
Air Fuel Rail: head and combustion chamber planning, spark plug positioning;
Lubricant distribution;
High altitude operation;
Plug fouling under extreme ambient conditions.
This project has taken Aprilia through the creation of a totally new engine, with unique characteristics. With DITECH, a tremendous reduction of oil an fuel consumption and very low emission of exhaust smoke has been possible, without sacrificing “top end” performance and great mid range torque of a classic two stroke engine.
The potential of this new engine technology is very high, due to the relatively simple emissions package required to meet coming anti-pollution laws.