The implementation of the IFP developed Compressed Air Assisted Fuel Injection Process (named IAPAC) in a two-stroke engine allows the introduction of the fuel separately from the scavenging air, which in consequence minimizes fuel short-circuiting. The inherent mechanical principle of the IAPAC process which uses the crankcase compressed air to finely atomize the fuel, provides the advantages of direct injection but in addition uses conventional low pressure automotive type injection technology with commercially available gasoline injectors.
In earlier work we showed an example of the application of this fuel injection technology to a PIAGGIO single cylinder 125 cc scooter two-stroke engine.
In this paper, an update of the results obtained with this new engine is presented and confirms the ultra-low emissions capability for two-wheeler application. This technology is also used with other IAPAC 2-stroke engines of various size and displacement to demonstrate how the application of IAPAC to marine outboard 2-stroke engines, is a good answer face to the new environmental regulations.
The EPA 2006 regulation can easily be met over the whole outboard engine power range with associated significant fuel economy benefits. The Bodensee stage 1 regulation can be met without catalyst, while the addition of a catalyst (at least for the medium to the high engine power range) will be necessary to meet the Bodensee stage 2 regulation.
It has already been reported in the previous work how careful attention has been paid to ensure that the IAPAC system remains mechanically simple and keep the additional cost as low as possible.
Finally, a brief cost impact analysis of a conversion of conventional 2-stroke engine to IAPAC is here presented. The ways of possible further cost reduction are also discussed.