Leighton, S. and Ahern, S., "Fuel Economy Advantages on Indian 2-stroke and 4-stroke Motorcycles Fitted with Direct Fuel Injection," SAE Technical Paper 2003-26-0019, 2003, doi:10.4271/2003-26-0019.
The Indian motorcycle and scooter market is faced with the combined challenge of exhaust emissions control from the environmental perspective and fuel economy demands from the consumer. Indian motorcycles are unique in their strong focus on reduced fuel consumption and this has resulted in the development of engines with quite different combustion characteristics in comparison to their European and ASEAN counterparts.Aprilia, Peugeot and Piaggio have recently released new scooter models utilizing air assist direct injection on their small 2-stroke engines to meet the ever increasing pressure on exhaust emissions, fuel economy and performance. These new scooter models are achieving good acceptance with the customer due to their combination of superior performance and improved fuel economy.Recent investigations by Orbital on Indian scooters and motorcycles show that the air assist direct injection system can be applied to Indian 2-stroke engines to meet the Indian 2005 emissions requirements without a catalyst and simultaneously provide a 30-35% fuel economy improvement on the Indian Driving Cycle (IDC). These results are superior to today's good 4-stroke fuel economy motorcycles and advance the 2-stroke motorcycle to best in class fuel economy status.Investigations have also been conducted by Orbital regarding the application of this air assist direct injection system onto Indian 4-stroke motorcycles. This study has shown good results with a fuel economy improvement of 12-15 % over the current levels. This is a unique achievement and is potentially more cost effective than the fitment of port injection systems when considering the fuel cost saving available with air assist direct injection.System descriptions, engine and vehicle performance, fuel economy and emissions capability test data are discussed in the following pages.