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Old 08-06-2006, 04:38 AM   #5
Scooby Specialist
Member#: 64494
Join Date: Jun 2004
Location: Australia
2001 V7 sti


If it was a balancing issue (and I'm not saying its not), why do the engine builder which balance their engines still modify the cranks?

I recently started a thread based on balancing of subaru crankshafts. The fact is the subaru crank cannot accomodate counterweights large enough to cancel out the weight of the rod/piston. Therefore the crankshaft is considered to be a "coupled" type crank which relies on the two adjacent journal loads to cancel each other out. What I am saying is the 2 front cylinders cancel each other out due to them being 180 degrees apart on the crank. This puts extra load on the main journal between them.

What I am getting to here is if you fit heavy rods and heavy pistons you are increasing the load through the crank which would increase any amount of twisting and hence increase the chance of oil failure (if this theory is correct??).

Does anyone know the statistics of what typically fails, is it mains or rod journals and is it any journal in particular?
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