Estimating Diesel Engine Performance by indirect Methods

The feasibility of using exhaust temperatures and injector nozzle needle lift duration to predict power output and fuel consumption of a diesel engine was investigated using an instrumented John Deere 4440 tractor. Using data obtained during a series of PTO dynamometer experiments, regression models were determined correlating the needle lift duration, exhaust temperatures, and engine speed with the parameters of interest. The models were subsequently tested under normal tractor operating conditions on a commercial farm.

Fuel flow and engine power output were accurately predicted from engine speed and needle lift duration and both these variables could be measured using one needle lift sensor. Engine power estimation from exhaust temperature measurements proved unsatisfactory due to the slow speed of response to changes in engine load.