PPS Lab 3 - Variable timing

Certification Assistance for Marine Engineers

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Propulsion Plant Simulator, Level Two
British Columbia Institute of Technology
Pacific Marine Training Campus
By: Martin Leduc Jan 22, 1999

Persons wanting to obtain the Canadian marine engineering license, or chief endorsement, need to complete the PPS L1 and L2 courses, in which they will have to carry out five labs. These are my results for one lab for your comparison. Findings are based on observation carried out and graphs not presented here.


Sulzer RLB
Variable Injection Timing
Lab 3



This lab was performed to study the injection timing in relation to the loading of the engine. The Sulzer RLB utilises a fuel pump which adjust both the start and end of the injection cycle in order to maximize engine performance.


Method of investigation

Procedure . The procedures set forth in the PPS Level 2 Course booklet were followed. The main ideas are as follows: With the engine operating on heavy fuel and within normal parameters. Using the action editor feature, the fuel link was increased, loading the engine, over a period of fifteen minutes.

The experiment was performed a second time with the Diesel Fuel Oil instead of Heavy Fuel Oil .



Equipment Used. The simulator used for this particular experiment was the NOR Control TEC 2000, simulating a Sulzer RLB. The RLB is a slow speed, six cylinder, two stroke diesel / heavy fuel engine. The engine drives a fixed pitch propeller directly couple to the engine. A shaft generator is also couple to the main drive shaft, but was not engaged at the time of experiments.

Data. The parameters of combustion and timing were recorded by the simulator’s "cylinder indication". The position of the fuel rack and other data was recorder using the "pen recorder" function. Results for experiment one can be found in Appendix A - C, D - F graph results from experiment two.



The experiments serve to illustrate the operation of the Variable Injection Timing feature for the RLB. The start of the injection stroke remains constant up to about 65% loading on the fuel link, at which point, the timing began to retard. This retarding of the injection prevented early ignition of the fuel, which would cause undue stress on the engine’s various parts.

The timing continues to be retarded until the pump began advancing it. At this point, more time is needed to completely burn the larger amount of fuel. But at the same time, the maximum pressure (Pmax) is falling further behind it’s target 5 degrees after top dead center, where the Engine is most efficient. Thus the advancing of the timing.

In the second experiment the findings were relatively similar to those of the Heavy Fuel Oil experiment. Some exceptions as illustrated in Appendix C and Appendix F, were the start of injection, start of ignition were not as retarded as the HFO experiment. The P max was greater with HFO, as were the T max.

Overall the engine seemed to be under more stress with the burning of the Heavy Oil as opposed to the Diesel oil.


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