FlexDI - Gaseous fuels including CNG
As crude oil production plateaus, CNG discoveries and production is set to increase. CNG is fast becoming an important fuel in road transport in many regions. CNG is a fuel which offers very high combustion knock tolerance leading to the use of high compression ratios and intake boost pressures.
Direct injection can overcome the power reduction typical of port injected CNG systems caused by displacement of intake air in naturally aspirated engines.
CNG is ideal for extended lean combustion provided a stratified charge can be provided to start combustion. FlexDI is capable of providing stratified lean combustion for enhanced fuel efficiency and reduced emissions. This means that engines can produce lower carbon emissions with less NOx. After treatment systems can reduce in cost and complexity.
Boosted engines also benefit from FlexDI through stratified charge control, multiple strike injection and high boost levels at low engine speeds. Valve timing may be fully optimised for low speed boost with no fuel charge loss through the exhaust port due to the fully flexible injection timing.
FlexDI offers the option to use existing FlexDI Gasoline engine designs for Direct Injected CNG with modifications to the fuel injection system and compression ratio to optimise the engine efficiency. Engine design and components are the same for gaseous and liquid fuel FlexDI engines leading to lowest cost power-train solutions.
FlexDI offers:
- Improved specific power and torque output
- Enhanced boosted engine economy and performance
- Multiple strike injection for charge stratification
- High EGR tolerance
- Extended lean limit operation
- Lower carbon emissions
Lowest cost after-treatment
