Natural gas engine close to certification

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Certification of Cummins Euro 6 ISL G natural gas engine is expected in October. The 8.9-litre engine is available from 250 to 320bhp for alternative fuel bus applications, with a peak torque of 1356Nm.

It uses a combination of cooled Exhaust Gas Recirculation (EGR) with stoichiometric combustion. Cummins cooled EGR lowers combustion temperatures and reduces engine out emissions and noise. Stoichiometric combustion, where fuel is burned completely, ensures an oxygen free exhaust. It enables the use of highly efficient three-way catalyst aftertreatment. The maintenance-free, three-way catalyst technology is an effective, simple, passive device, packaged as part of the exhaust muffler, providing consistent emissions control across the operating range.

For Euro 6, ISL G engine requires minimal changes from Euro 5. A closed crankcase ventilation (CCV) system is added and the electronic controls are upgraded. The new remote mounted CCV system recycles crankcase blow-by gases to minimise exhaust emissions. An updated electronic control module is required to manage the OBD requirements for Euro 6.

The engine runs on compressed and liquefied natural gas or bio methane.

John Burgess, General Manager for Cummins’ gas engine business, said: “Due to the ultra-clean nature of natural gas products, only a three-way catalyst aftertreatment is needed, with no SCR Adblue injection required. Cummins is working with the authorities to clarify this and enable certification of the ISL G.”