jimmys wrote:I investigated an accident medium speed 275 mm bore. The running gear came out the crankcase via a large hole. No deaths.
In order to improve peak pressure and power for sales reasons the engine timing was advanced to 20 degrees. Normally 12 to 15 degrees.
The fracture started in the gudgeon pin oil holes and stress was showing similar to Big Petes pics in the rod. I did a manual calculation and was not satisfied with the stresses in the engine. We were monitoring a sister vessel with Dive Time equipment to get accurate pressures. I said it was overstressed. The engine builder was not happy with the calculation.
Gov UK sanctioned a finite element analysis on the engine. A computer stress analysis using a suite called PAFEC, I carried it out. It takes a long time to run this.
The engine was over stressed. I would always advise further investigation when you see any faults in rods.keeps,pins etc.
You must watch with variable timing it is easy to overstress. Big pumps every cylinder, push rods, big springs, right up my street. A KGF is far too modern.
PS not happy bunnies at the builder. DOT not flavour of the month.
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