Quote:
Originally Posted by chris_seven
Does this mean that the web is only 5mm thick for the 70.4mm cranks with the 24mm rod?
Do you know what type of vibration occusrs is it a torsional or a lateral? Shedding flywheels sounds like torsionals .
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1mm per side so 6mm.
I am no Engineer but I believe it is lateral. I imagine that the throws are bending along an axis from the center of one rod journal to it's opposite journal.
Porsche played with many journal diameters on the 911 engine since 1965. The The 3.2 production car had a bump in journal size along with the 3.6 to 35mm. But it did not help to control the harmonics that plagued the 3.6. They simply ran out of room.
Engineers settled upon 53mm diameter. And ran that dia. exclusively from the inception of the 9 bolt crank on the competition cars and the GT-3's.