ISB6.7 G

Power 200 - 240 hp
149 - 179 kW
Torque 520 - 560 lb-ft
705 - 759 N•m
Certification EPA 2017


Medium-Duty Truck School Bus Transit Bus Natural Gas Engines


In 2016, Cummins Westport will introduce a new dedicated natural gas engine for transit, shuttle and school bus, medium-duty truck, and vocational vehicle markets. Based on the Cummins ISB6.7 diesel platform, the Cummins Westport ISB6.7 G will offer up to 240 hp (179kW) and 560 lb-ft (759 Nm) of torque, and will be available with automatic transmissions. Certified at launch to 2016 U.S. Environmental Protection Agency (EPA) and California Air Resources Board emissions standards, the ISB6.7 G will also meet 2016 EPA GHG requirements.

The ISB6.7 G features the same advanced combustion controls with Three-Way Catalyst (TWC) as Cummins Westport’s ISL G & ISX12 G engines. It operates on 100 percent natural gas, which can be carried on the vehicle in either compressed or liquefied form (CNG / LNG respectively). It can also run on 100 percent biomethane or renewable natural gas, which meets published Cummins fuel specifications.

For more information including pricing and additional technical information, please contact your Cummins representative. If you need help finding a representative, the Cummins Sales and Service Locator tool can help.

Advertised Horsepower 240 hp 179kW
Peak Torque 560 lb-ft 759 N•m
Governed Speed 2,400 rpm  
Type 4-cycle, spark-ignited, inline 6-cylinder, turbocharged, CAC  
Displacement 409 cu. in. 6.7 L
Operating Cycles 4  
Aftertreatment Three-Way Catalyst (TWC)  
Fuel Types CNG / LNG / Biomethane  
Availability  2016  
Engine Model Advertised Horsepower
Peak Torque 
lb-ft (N•m) @ rpm
ISB6.7 G 240 240 (179) 560 (759) @ 1600  2400 rpm
ISB6.7 G 220 220 (164) 520 (705) @ 1600  2400 rpm
ISB6.7 G 200 200 (149) 520 (705) @ 1600 2400 rpm

Preliminary Ratings - subject to change

  • Advanced Combustion Technology – The ISB6.7 G uses the same Stoichiometric cooled Exhaust Gas Recirculation (SEGR) combustion technology, spark ignition, and simple TWC aftertreatment as the ISL G and ISX12 G natural gas engines. The cooled-EGR system takes a measured quantity of exhaust gas and passes it through a cooler to reduce temperatures before mixing it with fuel and the incoming air charge to the cylinder. SEGR results in improved power density and fuel economy and enables the use of a TWC for emissions control.
  • Three-Way Catalyst Aftertreatment – Three-Way Catalysts (TWCs) are effective, simple devices, packaged as part of the muffler, that provide consistent emissions control performance and are maintenance-free.  No Diesel Particulate Filter (DPF) or Selective Catalytic Reduction (SCR) systems are required.
  • Proven Design – The ISB6.7 G shares many base engine components with the ISB6.7 diesel engine and shares the emissions architecture of the ISL G and ISX12 G, including wastegate turbocharger, a high-energy ignition system controlled by the CM2180A Engine Control Module, and similar fuel module design.
  • Fuel Capability – Natural gas can be stored on the vehicle in either compressed (CNG) or liquefied (LNG) form. The ISB6.7G can also operate on renewable natural gas or biomethane that meets fuel-quality specifications.

Overall, maintenance for the ISB6.7 G is similar to that of diesel engines, but there are a few key differences:

  • Motor oil specifically formulated for natural gas engines is required. Do not use diesel engine oil in a natural gas engine.  If diesel engine oil is used, valve torching, piston scuffing and reduction in spark-plug life will occur.  Cummins has recently reviewed natural gas engine oil requirements and issued a new natural gas engine oil specification - CES 20085.  For more information, see the links below or visit Cummins QuickServe Online:
Maintenance Item Distance Hours Months
Check CAC cooler, piping, and Air cleaner 7,500 mi (12,000 km) 250 3
Oil and Filter* 22,500 mi (36,000 km) 750 12
Spin-On Fuel Filter 30,000 mi (48,000 km) 1,000 12
Spark Plugs 22,500 mi (36,000 km) 750 12
Overhead Adjustment 45,000 mi (72,000 km) 1,500 18
Standard Coolant 60,000 mi (96,000 km) 2,000 24
Crankcase Ventilation Filter 60,000 mi (96,000 km) 2,000 24
Air Cleaner / Element Follow manufacturer's published recommendations

* Requires Natural Gas Engine Oil - For more information click here.
  Preliminary intervals - subject to change.

  • Default interval is the hours stated. Interval is whichever comes first – hours, miles or time.
  • Based on a normal duty cycle of 30 mph average speed.  Distance intervals will increase or decrease based on average speed.
  • Refer to QuickServe® Online or Owners Manual for complete details on maintenance intervals.

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