ISL G for School Bus (2013)


ISL G for School Bus (2013)
Cummins Westport ISL G.
The Natural Choice.
The ISL G combines all the advantages of clean-burning, natural gas engines with "no compromise" performance for school bus fleets. The ISL G meets current U.S. Environmental Protection Agency (EPA) and California Air Resource Board (ARB) emission standards, as well as 2014 EPA and U.S. Department Of Transportation (DOT) fuel efficiency and greenhouse gas (GHG) regulations.

Lower Operating Costs.
The ISL G sets a new benchmark for lower alternative fuel school bus life cycle costs. The combination of lower natural gas fuel costs and low incremental maintenance costs make it possible to save valuable dollars with a natural gas-powered fleet. The ISL G works with natural gas carried on the vehicle as either compressed natural gas (CNG) or liquefied natural gas (LNG). It can also be fueled using biomethane -- renewable natural gas made from biogas or landfill gas that has been upgraded to pipeline and vehicle fuel quality.

Proven Parts. Proven Performance.
Ratings range from 250-320 horsepower (186-239 kw). Standard features include electronic engine control features and a proven wastegate turbo from Cummins Turbo Technologies for impressive low-end torque and transient response. The ISL G shares 80% of its heavy-duty components with its diesel counterpart, the Cummins ISL9, including the fully-skirted block. This increases durability and reliability while reducing the overall cost.

Maintenance-Free Aftertreatment.
The ISL G features spark-ignited Stoichiometric cooled Exhaust Gas Recirculation (SEGR), in which the ideal air/fuel mix results in no unburned fuel or oxygen in the exhaust stream. This enables the use of a proprietary Three-Way Catalyst, which is packaged as part of the muffler and is totally passive. It does not need regeneration, Diesel Exhaust Fluid (DEF) or any maintenance.

Better. For Years Ahead.
The Cummins Westport ISL G comes with one of the most comprehensive base warranties in the industry, for 5 years and 100,000 miles (160,935 km). Plus, our new extended coverage plans offer a big advantage for school districts on a tight budget.

Better Is In The Details.
The Cummins Westport ISL G is designed to deliver better performance from a domestically-sourced fuel. It is easily customized using the many electronic engine features and adjustable parameters.  Maintenance is virtually unchanged from previous models. Plus, every ISL G is backed by the largest and most capable customer support network in the business.

For more information on the ISL G, visit

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, School Bus, Natural Gas

See ISL PowerSpec Engine Features

Product Finder Specifications

Natural Gas
Certification Level EPA 2013
Power 250 - 320 hp / 186 - 239 kW
Torque 730 - 1000 lb-ft / 990 - 1356 N•m


ISL G Urban Transit Bus and Refuse Truck
Maintenance Item^ Distance Hours Months
Oil and Filter* 7,500 mi (12,000 km) 500 6
Fuel Filter 15,000mi (1,000 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
Cooling System Flush 30,000 mi (48,000 km) 2,000 24
Overhead Set Adjustment** 30,000 mi (480,000 km) 2,000 24
Ignition Coil Extension 150,000 mi (240,000 km 10,000 5 yrs
Air Cleaner / Element Follow manufacturer's published recommendations
^Based on duty cycle of 15 mph / 25 kph average speed.  Distance intervals will increase or decrease based on average speed.
*Requires Natural Gas Engine Oil.  For customers using CES 20092 natural gas engine oils only, the recommended interval is 1,000 hours.
**Initial overhead set adjustment at 1,000 hours
  • Default interval is the hours stated.  Interval is whichever comes first - hours, miles or time.

  • Refer to QuickServe Online or Owners Manual for complete details on maintenance intervals.

Brochures Available

Title Bulletin Number Request View  
Cummins Westport ISL G Brochure 4971499 Request View  Download
Cummins Westport ISL G Brochure – French 4971503 Request View  Download
School Bus Engines Brochure (2013) 4971393 Request View  Download