ISL G for Urban Bus & Shuttle (2013)


ISL G for Urban Bus & Shuttle (2013)

Naturally Better. Cummins Westport ISL G Natural Gas Engine.

There are over 40,000 Cummins Westport natural gas engine-equipped vehicles performing cleanly and reliably today. Interest in natural gas engines is steadily growing throughout North America, with Cummins Westport natural gas engines widely recognized for their technological leadership in urban transit fleets. The ISL G combines all the advantages of clean burning natural gas with no compromise in power or torque. 

The ISL G uses Stoichiometric cooled Exhaust Gas Recirculation (SEGR) combustion to create the optimal combination of power, torque and low emissions levels. Stoichiometric combustion is the ideal ratio at which fuel and oxygen are both completely consumed.

The oxygen free exhaust stream enables the use of our proprietary Three-Way Catalyst (TWC). This completely passive device never needs additional fluids, regeneration or cleaning, and takes the place of a conventional muffler. Fuel for the Cummins Westport ISL G can be stored on the vehicle as compressed natural gas (CNG) or liquefied natural gas (LNG). The ISL G can also run on renewable natural gas (RNG) made from biogas or landfill gas that has been upgraded for vehicle fuel quality.

The ISL G shares 80 percent of its heavy duty components with its diesel counterpart, the Cummins ISL9. This increases durability and reliability while reducing the overall ownership cost. The troubleshooting capabilities (using Cummins standard software and diagnostic tools) are also shared.

Considering a Cummins engine purchase? 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.


Cummins PowerSpec is an electronic tool that makes it possible to tailor the operation of Cummins engines in every on-highway application.

Available for: On-Highway, Urban Bus & Shuttle, Natural Gas

See ISL PowerSpec Engine Features


Advertised Horsepower 280-320 hp 209-239 kW
Peak Torque 900-1000 lb-ft 1221-1356 N•m
Governed Speed 2200 rpm  
Clutch Engagement Torque 550 lb-ft  746 N•m
Number of Cylinders 6  
Net Weight (Dry)  1,625 lb 737 kg
Aftertreatment System Three-Way Catalyst (TWC)  

Product Finder Specifications

Natural Gas
Certification Level EPA 2013
Power 280 - 320 hp / 209 - 239 kW
Torque 900 - 1000 lb-ft / 1220 - 1356 N•m


ISL G 320 320 (239) 1000 (1356) @ 1300 2200 rpm
ISL G 280 280 (209) 900 (1220) @ 1300 2200 rpm


Proven Wastegate Turbo From Cummins Turbo Technologies
A simple, reliable design from the world leader in turbocharging technology.

Three-Way Catalyst (TWC) From Cummins Emission Solutions
TWCs are passive devices packaged as part of the muffler, and are maintenance-free. The ISL G des not require active aftertreatment such as a particulate filter or Selective Catalytic Reduction (SCR).

Fully Skirted ISL Diesel Engine Block
The high-strength, rebuildable design adds durability. Shares 80 percent of major engine components with the ISL9 diesel.

Stochiometric Cooled EGR
The ideal air/fuel ratio for complete combustion means zero oxygen in the exhaust, which allows use of the passive Three-Way Catalyst.

High-Capacity Electronic Control Module (ECM)
Provides full monitoring and control of engine sensors, the fuel system and the ignition system. Compatible with Cummins software and other diagnostic service tools.

High Energy Ignition System
Provides better performance, longer service intervals and improved spark plug and coil durability, plus self-diagnostics. A coil-on-plug ignition system eliminates the need for spark plug wires.

QuickServe® Online.
QuickServe Online sorts through 11 million Cummins engines and a million documents in seconds to find accurate, up-to-the-minute parts and service information about a customer’s engine. Every fact is instantly available, from part numbers, diagrams and supercessions to service bulletins and troubleshooting manuals, operation and maintenance manuals, literature, tools, catalogs and more. See for access information.

Genuine Cummins New And ReCon® Parts.
We stock parts for 100,000 individual part numbers at our Memphis Distribution Center, including both new (Genuine Cummins) and remanufactured (ReCon) parts. Our centralized distribution network assures next-day delivery almost everywhere in North America on parts orders received by midnight EST. Genuine Cummins Parts are of the highest quality and backed by the best parts warranty in the industry. And we are so confident in the reliability of Genuine Cummins ReCon parts that every one comes with a full Cummins warranty.

Training Every Technician.
Make sure your technicians have the training on all the latest technology. Cummins distributors offer local training using the same diagnostic procedures and repair techniques that are taught by our factory personnel.

Every Confidence.
All Cummins and Cummins Westport transit engines come with a standard 2-year/unlimited-mileage warranty with full parts and labor on warrantable failures.* This includes travel or towing when a bus is disabled or when further operation would cause additional damage. Major components are covered up to 3 years or 300,000 miles (482,804 km), whichever occurs first, on Cummins ISL9 and ISL G urban transit bus engines.

* Warrantable failures are those due to defects in materials or Cummins workmanship.

Better Extended Coverage.
For additional peace of mind, Cummins and Cummins Westport offer a variety of extended coverage plans to meet every transit operation’s needs. Check with your local Cummins distributor for details.

Better Service. Everywhere.
Cummins-powered urban transit buses are backed by the largest and most capable parts, service and support network in North America, with nearly 3,500 locations. Our authorized technicians are fully trained on all our engines, and have the necessary equipment and Genuine Cummins Parts to handle any type of service issue. Call 1-800-DIESELS™ (1-800-343-7357) for information and service locations.

Better Answers.
To learn more, visit or Assistance is also available by phone at 1-800-DIESELS™ (1-800-343-7357), or contact your local Cummins distributor or dealer. Product literature and additional information are always accessible online at You can also register all of your Cummins engines quickly and easily, and sign up for our Bus News electronic newsletter for important updates.


Overall, maintenance for the ISL 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.

Maintenance Item Miles/Kilometers Hours Months
Oil and Filter* 7,500 mi
12,000 km
500 6
Fuel Filter 15,000 mi
24,000 km
1,000 12
Coolant Filter 7,500 mi
12,000 km
500 6
Spark Plugs 22,500 mi
36,000 km
1,500 18
Coolant Change 30,000 mi
48,000 km
2,000 24
Valve Adjustment** 30,000 mi
48,000 km
2,000 24
Air Cleaner/Element Follow vehicle manufacturer’s published recommendations    

*Requires natural gas engine oil. For more information see the Product Information Bulletin available on
**Initial value adjustment at 1,000 hours.

For complete maintenance information, please consult your Owner's Manual or Operations and Maintenance Manual, available on QuickServe Online.

Brochures Available

Title Bulletin Number Request View  
2017 Transit And Shuttle Bus Brochure 5410747 Request View  Download
Cummins Natural Gas Parts Brochure 2878880 View  Download
Cummins Westport ISL G Brochure 4971499 Request View  Download
Cummins Westport ISL G Brochure – French 4971503 Request View  Download
Driver Tips Card For Natural Gas Engines 4971392 Request View  Download
Driver Tips Card For Natural Gas Engines - French 4971422 Request View  Download
School Bus Engines Brochure (2013) 4971393 Request View  Download
Urban Transit Brochure (2013) 4971427 Request View  Download