Engine Overview

The 4B/3.9L Cummins is a popular engine used in step van applications including bread, snack, uniform, and other commercial delivery vehicles from Oshkosh to Freightliners. This engine is also used in various industrial and construction applications.
 

NPD utilizes torque plating methods for boring and honing to ensure block straightness, which reduces break-in time and crankcase pressure. In addition, NPD uses OEM or equivalent pistons, rings, bearings, valves and gaskets, 
making sure that this engine will stand the test of time.

Dynomometer Testing

All of NPD's Complete Drop-In engines are 100% dyno tested 
prior to shipment. Computer controls ensure that each 
engine dyno test is conducted under standard, 
repeatable settings. Every engine is run through a warm 
up cycle; three separate cruise segments simulating light, 
medium and heavy throttle conditions; maximum torque 
and horsepower tests; both high and low idle tests; and a 
black light leak detection test with dyed oil, coolant and fuel.