ISL G for School Bus (EPA 2010)


ISL G for School Bus (EPA 2010)

Every Alternative:  Cummins Westport ISL G
The 8.9-liter ISL G has met EPA 2010 emissions standards since 2007 using Stoichiometric cooled-Exhaust Gas Recirculation (SEGR) spark-ignited combustion to create a high-performance natural gas engine.  Torque at idle and fuel economy are improved versus lean-burn engines by 30% and 5%, respectively.

Cooled EGR, in combination with stoichiometric combustion (the theoretical or ideal combustion process in which fuel and oxygen are completely consumed), creates an oxygen-free exhaust, which allows for the use of Three-Way Catalyst (TWC) aftertreatment.  TWCs are effective, simple, passive devices that are packaged as a muffler and are maintenance-free.  The ISL G does not require active aftertreatment such as DPFs or SCR.

The Natural Alternative.
The ISL G is rugged and reliable because it shares many components and parts with Cummins L Series diesels and is built on the same assembly line as Cummins diesels.  A wastegated turbocharger with electronic control for precise air handling and full drive-by-wire throttle control provide impressive diesel-like performance.

A new ECM provides full monitoring and control of engine sensors, fuel system and ignition system.  The ECM provides full interface capability to Cummins INSITE™ and diagnostic service tools.  It also provides Original Equipment Manufacturers (OEMs) and end users with the ability to tailor performance of the engine to fit the vehicle mission.

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, School Bus, Natural Gas

See ISL PowerSpec Engine Features

Engine Finder Specifications

Natural Gas
Certification Level EPA 2010
Power 250 - 320 hp / 186 - 239 kW
Torque 730 - 1000 lb-ft / 990 - 1356 N•m


Engine Model Advertised hp (kW) Peak Torque lb-ft (N•m) @ rpm Governed Speed
ISL G 320 320 (239) 1000 (1356) @ 1300 2200 rpm
ISL G 300 300 (224) 860 (1166) @ 1300 2200 rpm
ISL G 280 280 (209) 900 (1220) @ 1300 2200 rpm
ISL G 250 250 (186)  730 (990)  @ 1300 2200 rpm


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

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 School Bus Market Brochure 5410584 Request View  Download
Cummins Westport ISL G Brochure 4971499 Request View  Download
Cummins Westport ISL G Brochure – French 4971503 Request View  Download
School And Shuttle Bus Engines For EPA 2010 Spec Sheet 4971232 View  Download
School Bus Engine for EPA 2007 Brochure 4103787 View  Download