PSI ultra-low NOx propane engine receives EPA certification

November 3, 2020 By    

The U.S. Environmental Protection Agency (EPA) and the California Air Resources Board (CARB) have certified Power Solutions International’s (PSI) new 8.8-liter ultra-low nitrogen oxide (NOx) emission propane engine for the transportation market, the company announced.

Produced in collaboration with Navistar’s IC Bus brand, the 8.8-liter engine is certified to a NOx emission standard of 0.02 grams per brake horsepower-hour, making it one of the cleanest propane engines available on the market, according to PSI. The engine is certified beyond the EPA’s strictest emission standards and also exceeds CARB’s optional low NOx standard for heavy-duty engines.

“PSI is proud to support the growth of our customer IC Bus, which first introduced the 8.8-liter propane engine in 2015,” PSI CEO John Miller says. “We continue to make advancements to our 8.8-liter engine, which is clean burning and unmatched in power and performance in the transportation industry.”

The new engine offers 270 horsepower with 565 pound-feet of torque, comparable to PSI’s existing propane engines. The company will continue to offer its conventional 8.8-liter propane engine as well as the new ultra-low NOx version. The ultra-low NOx engine will power IC school buses. Production is anticipated early next year.

For the past few years, PSI and IC Bus have worked together on propane and gasoline-powered alternatives to diesel school buses in an effort to reduce NOx emissions, which are known to be harmful to humans and the environment, and contribute to ozone, smog and other air quality issues.

“IC Bus is proud to once again collaborate with PSI to bring a clean, powerful, high-quality alternative fuel engine to the school bus industry,” says Trish Reed, vice president and general manager of IC Bus.

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Brian Richesson is the editor in chief of LP Gas Magazine. Contact him at or 216-706-3748.

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