I would be really curious to see what kind of ignition advance @
cf6mech was having when his forged engine was struggling. If the engine was tuned past MBT the cylinder pressure could be significantly higher... However I don't want this to turn into a debate about who is a good tuner, and why. But he is one of the only to speak up and share his experience at this point. I don't think his crank was ever inspected he just replaced it but i cant verify that.
Would having a softer bearing be more resistant to damage via aggressive cylinder pressures by having more "flex" ability in them? If so that could explain the issues being seen. I have thrown a rod on E85, but have never taken the time to inspect it. I am curious to see what my bearings & crank look like. In the next few weeks ill inspect them. I also have logs of 'similar' scenarios showing my ignition timing and other variables that may be of use.
I really wish I had a setup locally that I could test on a dyno to see exactly where MBT was compared to my vehicles tune. I really want to find out what the limits on the OEM bearings really are as Don @ accelerated's solution seems to be the
only available after market option at this time. And we have a number of people in the 400-600HP club on OEM blocks running just fine at this time. Although I am sure it is on borrowed time and for all we know it could be due to production inconsistencies. Does anyone know anyone that had an engine fail running on pump gas where you would actually see detonation? Everyone that I personally know that has thrown a rod or had a drastic failure was on E85. In which you may not see knock... you may just see a bent rod due to cylinder pressure.
Again the reason for this debate is a number of shops are saying the OEM bearings are just fine (such as crawford with over 15k miles on OEM bearings with forged internals). As well as a number of other builders who say they prefer OEM bearings when possible. Just so few people with built engines have popped their head up and shared their experiences.
Personally i'm starting to lean towards doing my build with OEM bearings at this point and tuning extremely conservative on ignition timing during any load beyond highway engine loads.