How often do you see front irons crack?
 

Last weekend a friend of mine cracked his front iron at the dowel area next to the oil feed for the turbo on his s4 TII block. Needless to say, I was very surprised to see that his front iron cracked and not the rear one, which is the one without any reinforcement. Although he was boosting at 17 psi and only had 1300 miles on it, I expected the rear iron to break at the dowel area.
So, I guess that's pretty much my question: how often do you guys see a front iron crack?

Brian

Possible the front rotor detonated?

AFR? timing advance, split, knock count? do you have any idea about any of that? The s4 irons aren't the strongest, but I've been running 19psi on my s4 T2 motor for a little while now (few hundred miles) and haven't had any problems, but this is on race gas.

His afr's were about 11 - 11.5, advance was around 13 degrees, split was 11- 12, and he does not have a knock sensor. Also on 93 octane. Yeah, I definitely agree that the s4 irons are the weakest of the bunch. He's running on a megasquirt ecu btw.