Introducing the Cummins Westport ISX12 G natural gas engine - a new, larger-displacement natural gas engine. The ISX12 G suits a variety of heavy-duty vehicles, including regional-haul truck/tractor, vocational, and refuse applications. With a displacement of 11.9 liters and up to 400 hp and 1450 lb-ft of torque, the ISX12 G is the natural choice when considering alternative fuel for demanding applications. The ISX12 G operates on 100% natural gas which can be carried on the vehicle in either compressed (CNG) or liquefied (LNG) form. The ISL G can also run on renewable natural gas (RNG).
Featuring the same proven Stoichiometric cooled Exhaust Gas Recirculation (SEGR) combustion technology, spark ignition and simple Three-Way Catalyst (TWC) aftertreatment as the Cummins Westport ISL G engine, the ISX12 G delivers strong pulling power and heavy-duty durability and performance that customers can depend on.
For best reliability and durability, the recommended maximum GVW for line-haul applications is 80,000 lb (36,287 kg). Recommended gearing is 1400 rpm to 1450 rppm at cruise speed, to optimize fuel economy.
The ISX12 G meets 2013 U.S. Environmental Protection Agency (EPA) and California Air Resource Board (ARB) emission standards as well as the 2014 EPA and U.S. Department of Transportation fuel economy and greenhouse gases regulations.
|Advertised Horsepower||400 hp||298 kW|
|Peak Torque||1450 lb-ft||1966 N•m|
|Governed Speed||2,100 rpm|
|Clutch Engagement Torque||700 lb-ft||949 N•m|
|Type||4-cycle, spark-ignited, inline 6-cylinder, turbocharged, CAC|
|Displacement||726.2 cu. in.||11.9 L|
|Bore and Stroke||5.11 in x 5.91 in||130 mm x 150 mm|
|Oil System Capacity||12 U.S. gal||45.4 L|
|Coolant Capacity||26.5 U.S. qts||25.1 L|
|Net Weight w/ Std. Accessories, Dry||2,650 lbs||1.202 kg|
|Aftertreatment||Three-Way Catalyst (TWC)|
|Fuel Types||CNG / LNG / Biomethane
Methane number 75 or greater
Cummins Westport engines can accept a wide range of natural gas fuel compositions.
Use our Fuel Performance Specification Calculator to ensure compatibility.
|Engine Model||Advertised Horsepower
lb-ft (N•m) @ rpm
|ISX12 G 400||400 (298)||1450 (1966) @ 1200||2100 rpm|
|ISX12 G 385||385 (287)||1350 (1830) @ 1200||2100 rpm|
|ISX12 G 350*||350 (261)||1450 (1966) @ 1200||2100 rpm|
|ISX12 G 350*||350 (261)||1350 (1830) @1200||2100 rpm|
|ISX12 G 330*||330 (246)||1250 (1695) @ 1200||2100 rpm|
|ISX12 G 320*||320 (239)||1150 (1559) @ 1200||2100 rpm|
*Refuse/Vocational Truck Application Ratings
|Spin-on Fuel Filter||Daily Check|
|Oil And Filter*^||18,000 mi (30,000 km)||400||6|
|Coolant Filter **||67,500 mi (108,500 km)||1,500||12|
|Spin-on Fuel Filter*||45,000 mi (72,300 km)||1,000||12|
|Spark Plugs*||67,500 mi (108,500 km)||1,500||12|
|Overhead Adjustment*||67,500 mi (108,500 km)||1,500||12|
|Engine Brake Adjustment||270,000 mi (435,000 km)||6,000||24|
|Standard Coolant||270,000 mi (435,000 km)||6,000||24|
|Air cleaner / element||Follow vehicle manufacturers published recommendations|
* Assuming normal duty cycle/based on 45 mph (72.4 kph) average speed. Spark plug interval and overhead adjustment must be reduced for slower speed applications.
**Do not change if SCA above 3.
^Requires natural gas engine oil (CES20074)
Intervals for normal duty - must be reduced for lower average speeds/duty cycles.
Default interval is the hours stated. Interval is whichever comes first – hours, miles or months.
Refer to Owners Manual for complete details on Maintenance Intervals.