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Having a sharp edge on the oiling hole creates a stress riser. Stress risers greatly increase the likelihood of a cracking forming. Once a crack forms, even at a microscopic level, it will continue to grow until it reaches the other side. In this case the other side would be the other side of the journal.
Having a sharp edge on the oiling hole creates a stress riser. Stress risers greatly increase the likelihood of a cracking forming. Once a crack forms, even at a microscopic level, it will continue to grow until it reaches the other side. In this case the other side would be the other side of the journal.
Good post & good info
Yeah, im sure most are not familiar w/the term "stress riser". I work in the mechanical industry, so we reference those techniques as general practice
Hard to tell from pic, but it doesn't look like this one started at the oil port pictured on the rod journal. May have been on the other side.
Nothing is indestructible.
Two sides to every story. Maybe that engine had been rattled for a long time. Occasionally pump gas, timing and high boost get out of hand . Or its an auto x car that shakes the tires 100's of times with a QM. RS motors broke a few STOCK cranks with that setup. Eventually the weakest link will break. Big tires, built diff's, a strong clutch and a loose surface is a hard environment.
FWIW, TS comp has used 100's of the old style 100mm billet cranks for years with a high success rate. If he was running into issues, He would most likely chose another route.
Manley made the change recently and it should add even more strength . However, tuning and environment are still relevant IMO.
Actually it does look like it came from the oil hole. If it would have cracked on the oil hole facing the camera it would have broken on the other side of the journal.
For those of you who don't know Robert Garcia of So Cal, there is no Evo that can hold up to his abuse. Lol
Anyway, this is his Manley billet 88mm crankshaft oil journal after 10,000 miles.
Last edited by 2006EvoIXer; Nov 26, 2018 at 03:14 PM.
Meanwhile, English Racing uses an Eagle forged 88mm to make 1400whp. Why do they use it? Because it's the only one that doesn't crack out of testing all the cranks at 1100-1200whp+...
