Cummins Logo International Logo
Contact UsRSSTwitterYouTube

Cummins_2013_ISX15Spec’ing for Leading Fuel Economy

When you have customers whose priority is reducing fuel use, the first step is to make sure that they start with a Cummins ISX15 engine with ratings between 400 hp and 475 hp. These ratings have been specifically programmed with an optimized torque curve that delivers extra power in the low end of the rpm range. This makes the engine very efficient when running at 1250 to 1350 rpm. The engine being capable of delivering the necessary power while operating at lower, more efficient, cruise rpms is commonly referred to in the industry as “downspeeding.” Customers are able to maintain efficient road speeds while their engine is running slower, ultimately saving fuel.

The combination that delivers the best fuel economy possible is the SmartAdvantage™ Powertrain from Cummins and Eaton.® This integrated powertrain has been designed to deliver the performance to efficiently sustain cruise speeds of 62 to 65 mph in the 1160 to 1240 rpm range. It has been proven to deliver fuel economy savings of 3% to 6% in line-haul operations when compared with the best-spec’d ISX15 engine and the traditional wide-step automated transmission combination from Cummins and Eaton.

The formula for determining the proper gearing is based on a number of factors, including engine rating, average load and tire size. A gearing calculator available in PowerSpec by going to Feature Description and selecting Gear Down Protection. To download PowerSpec, visit

Back to the home page


Terms and Conditions  ©2022 Cummins Inc., Direct Marketing, Mail Code 60610, 500 Jackson Street, Columbus, IN 47201 U.S.A.

We use cookies on this site to enhance your experience. By clicking any link on this page, you give consent for us to set cookies. For more information, see our Privacy and Legal page

Got it!