26/11/2009 - Direct Injection

To understand how direct injection works we need to take a quick step back to understand how a standard modern engine is fuelled.. Standard petrol injected engines inject the petrol into the inlet manifold close to the engines inlet valve (port injection). The JTG liquid LPG injection and Sequential Vapour Injection systems such as Eurogas and Emer work the same way by injecting LPG into inlet manifold close to the inlet valve also. The air flow then draws the air and fuel mixture into the combustion chamber when the inlet valve opens. Of course, when we choose LPG operation the petrol injector is turned off and the LPG injector takes over.

Direct injection engines such as the new SIDI Commodore have their petrol injector located in the combustion chamber. This provides many advantages allowing better fuel consumption and lower exhaust emissions. The environment inside the combustion chamber is quite hostile (extreme temperatures and pressures). The petrol injector is designed to withstand these conditions by flowing petrol through the component to prevent overheating. 

If you introduce LPG via the inlet manifold via port injection LPG systems, the petrol injector is turned off, leaving it exposed to these extreme conditions. Icom has developed a Direct Injection LPG system that injects the LPG into the combustion chamber providing us with a sound economical and performance solution whilst protecting the integrity of the petrol injector.

Be aware that standard Sequential Vapour Injection Systems installed to these engines can cause performance, drivability and component durability issues. 

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