Originally Posted by
Jon Wehrenberg
Mark is right about Prevost having a fix for the seal leak. In our classes last week we learned a little about the Volvo engine and the information came from guys with a service background so I tend to think it is true. Volvo approaches the EPA standards a little differently from the others (such as Detroit) and they claimed mileage is back up where it was prior to being strangled with EGR. Volvo introduces less exhaust gas into the intake and as a result mileage has climbed. The engine also has a different torque curve from the Detroit, producing maximum torque early in the rev range and holding it longer at the maximum before it drops off. The Detroit develops maximum torque later, it peaks and drops off instead of being a nearly flat curve like the Volvo.
The significance is the Volvo is run at a lower RPM allowing it to run in high gear sooner which translates into better fuel economy. We worked near the Volvo engine when it was running and it is definitely a very quiet engine. I hope it proves to be as reliable as the Detroits have been.