Tuesday, May 6, 2014

How is firing order for main engine decided? Why firing order is 1-7-2-4-6-3-5 instead of 1-2-3-4-5-6-7?

There are some factors called the Primary and secondary Force balancing and Primary and Secondary Moment Balancing for an Engine. A firing Order which gives minimum or Zero forces and moments on the Crankshaft of the Engine will be selected. This is a trial and error method. There are formulas in which you put in values and determine the forces and moments. The order is then selected accordingly.

To support a load along the length it is advisable to simply support at extremities  Since a momentary force ...like a see saw . when one side up other side down... 1 7 2 4 6 is on the same side but at a moment 4 and 6 is divided by 5 . so the crankshaft is balanced..

There is no hard and fast rule applied in deciding firing order in a multicylinder engine. in one word the answer is "balancing". 

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