DDEC V ENGINE DRIVING TIPS In general, when using a 7- or 9-speed transmission, you should always downshift between 1250 and 1300 rpm. This is true even on steep grades with heavy loads. When using an 18-, 15- or 13-speed transmission, you will need to downshift at an rpm that allows “less than rated” rpm before throttle application in the next gear down. You may want to limit engine speed to 1900 rpm in all gears. The Series 60 provides horsepower through 2100 rpm, but fuel economy is not as efficient above 1800 rpm. changes of the air flow within the air intake plumbing. Electronic engines can actually deliver more fuel at lower engine speeds than at rated speed.
One difference you may notice with the EGR equipped engine is underhood noise. The gear train has been redesigned for quieter operation, and the EGR gas flow may be noticeable to the tuned attentive ear. The turbocharger operates at higher boost pressure forcing EGR gas flow through the EGR plumbing which is a noticeable change from non-EGR equipped engines. In some situations the driver may believe he/she has experienced a charge air cooler system leak. Even connecting trailer light and air hoses, the driver may hear a different tone (exhaust and underhood with the engine idling.) If equipped with a turbo boost gage, the driver may occasionally note intake manifold pressure exceeds 35 psi.
Low rpm operation should feel greatly enhanced due to the characteristics of the variable nozzle turbocharger. Engine response should be almost instantaneous below peak torque engine speeds. This should encourage progressive shifting especially during slow vehicle speed operation. If you decide to drive at lower rpm's for improved fuel economy, don't let different engine noises throw you off guard. The Series 60 sounds quiet at 1400 rpm, almost as if it had quit pulling. Don't believe it! If you had a boost gage to look at while driving, you would notice the turbocharger maintaining steady intake manifold pressure, even as rpm's fall.
Depending on the air intake arrangement, you may also experience a “chuffing” sound as the engine starts to pull hard at lower rpm's. This is caused by the velocity 38 All information subject to change without notice. DDC-SVC-MAN-0039 Copyright © 2009 DETROIT DIESEL CORPORATION