Navistar Adding The Cummins ISB To Trucks and Buses
Great news!....the Cummins ISB engine will be available starting on September 3rd for Navistar IC CE series school buses. The medium duty engine is a perfect fit. I know this from experience because of the performance we have received from these engines.
The 6.7 liter engines interface very well with the 2000 series Allison transmissions we're using and don't skip a beat 99% of the time. The few failures we've had (water pump, turbo, leaking exhaust manifold) are minor glitches and all of these problems occurred during warranty. Since then they have been the best performers in the entire fleet
The IC engines previous to this change all ran on EGR technology without SCR (selective catalytic reduction). Now SCR will be a mainstay with the overall bus design. The production date for CE series school buses will be later in January 2014. The Navistar medium duty truck market will also be using the ISB which will be going into production in December.
The Cummins ISB was introduced in 2007 with a larger 6.7 Liter displacement than the previous 5.9 L engines. The design came out originally with a 350 HP rating and 650 lb ft torque. This model came out because of the emission standards required to reduce particulate matter out of the exhaust. The ISB is equipped with an exhaust recirculation system (EGR), diesel particulate filter (DPF) and a variable geometry turbocharger (VGT).
Exhaust emissions have been reduced by as much as 90% and the high ouput version which runs at 385HP 850 lb ft torque has the selective catalytic reduction (SCR) system using the DEF diesel exhaust fluid. Along with all of this is a Bosch high pressure fuel injection pump that was designed to lower noise and vibration. I give these engines two thumbs up with less noise, more reliability and in our case a great dealership in town who help us out anytime we need it.