PSI 8.8-liter engine. Click to enlarge.

The PSI 8.8-liter engine is engineered to deliver the highest torque at the lowest speed. With a rating of 565 lb-ft (766 N·m) at 1500 rpm, the high torque-low speed design greatly benefits stop-and-start applications to allow immediate acceleration after stops and greater hill climbing capability.

This not only improves startability and gradability, but also eliminates excessive noise, heat and vibration associated with constant engine revving. Minimal revving reduces engine wear, oil usage and maintenance, while increasing durability and efficiency.

Until now, the propane vehicle market had been supported by underpowered engines that run at high-speeds to get the required power. The PSI 8.8-liter engine is an economic, low-speed solution that boasts diesel-like performance, high durability, reduced noise and overall wear with all the benefits of alternative fuels.

—Gary Winemaster, chairman and CEO, PSI

The CE Series school bus powered by propane also integrates the Allison 2500 transmission with FuelSense to maximize fuel economy.

IC Bus will manufacture CE Series school buses with propane out of its school

bus assembly plant in Tulsa, Okla. Deliveries will begin in summer 2015 and buses will go into service for the start of the 2015/2016 school year. The CE Series will also be on display at this year’s National Association for Pupil Transportation (NAPT) Annual Summit in Kansas City, Mo., 8-11 November.