Cummins has introduced its 2017 X15 heavy-duty engines and the coming X12. The new X15 replaces the ISX15, meeting all 2017 EPA emissions and fuel-efficiency standards, of course, while adding lower fuel consumption, extended service intervals, and enhanced performance across a 400-to-605-hp ratings range. There are two configurations, aligned with duty cycles, the X15 Performance Series and the X15 Efficiency Series.

Next year’s X15 engines will offer as much as 3% better fuel economy than 2016 models, and up to 20% more than 2012 versions, Cummins said.

The new platform benefits from an optimized compression ratio, air handling system, and cam profile to increase both fuel efficiency and performance capability.

Look for full production to start in January 2017, with as many as 1400 engines built in Q4 2016.

Cummins says its new X12 presents the highest power-to-weight ratio of any engine in the 10-to-16-liter class, aimed at regional-haul, intracity delivery, and vocational trucks. The 11.8-liter engine is rated up to 475 hp and as much as 1700 lb ft of torque, the peak coming at a low 1000 rpm and staying there to over 1400 rpm, reducing the need for gear shifting.

The new engine is based on the confusingly named ISG, jointly developed with Chinese partner Foton, with U.S. engineers taking the lead role, and used in China for the last two years.

While it will be built in the Cummins plant in Jamestown, NY for its 2018 North American launch as the X12, the G Series has been manufactured at the Beijing Foton Cummins Engine Co., a 50-50 joint venture between Cummins and Foton.

The X12 has been North Americanized, addressing only the emissions/aftertreatment system and packaging factors. It has a dry weight of 2050 lb (930 kg), which is said to be 150-600 lb lighter than all medium-duty competitors. It sports a single-cam-in-head design with roller valve train and high-efficiency intake ports to minimize complexity.

Today’s ISX12 and ISX12 G natural gas engines continue to benefit from ongoing fuel-efficiency improvements, says Cummins, and will be compliant with Phase 1 greenhouse gas and fuel- efficiency standards to be fully implemented in 2017.

The ISX12 G engine will continue as the heavy-duty platform for natural gas, but the diesel-fired ISX12 will be replaced by the X12. No word yet on whether the latter will appear in a natural-gas version.

The X15 Performance Series, rated at 485 to 605 hp, aims for heavy-haul, vocational, and emergency-vehicle applications. An upgraded high-flow air-handling system gives a faster pedal response for enhanced driveability at full payload and steep-gradient climbing. Peak torque of up to 2050 lb ft is delivered across a very wide engine rpm range, something drivers love. Equally strong — and quiet — is the engine braking, with over 450 hp available at just 1500 rpm and up to 600 hp at 2100 rpm.

We had the chance to see for ourselves. In a direct comparison to an identically spec’d ISX15, the new engine was distinctly superior on both counts. Even dramatically superior.

For linehaul and regional applications, the X15 Efficiency Series offers ratings from 400 to 500 hp and up to 1850 lb ft of  torque available at 1000 rpm. When integrated with the Cummins and Eaton SmartAdvantage powertrain, it delivers what the engine maker calls “class-leading fuel economy”.

Its cost of maintenance will be reduced by almost half over the first 500,000 miles, compared to the 2010 engine. Oil-drain intervals for typical line-haul applications are extended up to 50,000 miles, and will stretch to as much as 80,000 miles for trucks running at 6.5 mpg or higher with OilGuard – an oil analysis program to be introduced by Cummins. Fuel-filter change intervals are also extended up to as much as 50,000 miles, and the crankcase breather filter is now maintenance-free.

Diesel particulate filter cleaning intervals have been pushed out to 800,000 miles.

Every X15 is factory-ready to enable Over-the-Air (OTA) engine programming and customization when connected to an approved telematics system. Advanced tools using Cummins Connected Calibrations and Connected Tuning applications mean the X15 can be adjusted and optimized over the air — without visiting a service bay. Meaning that a truck that’s been set up for over-the-road long hauls, for example, can be re-calibrated or re-tuned for stop-and-go local work literally over the air, on the spot.

The fleet manager sends the update to the truck from his computer at home base and the driver is then prompted to finalize the calibration update when he next shuts down. A backup of the original configuration is created just in case.

The X12 will get the same connected capabilities.