I think I finally killed the 2.5L at Nelson Ledges. Conditions were ripe for the typical SVT oil starvation-induced rod bearing failure, with several right-hand redline turns per lap. Time to start looking for a 3.0L...
Unless the oil level got too low, the root cause of the spun bearing is stretching of the connecting rod and/or the rod bolts. The stretching of the rod results in loss of the clamping force that anchors the bearing sleeve inside the bore. Once you lose that, the bearing will spin because the tabs are not strong enough to hold it in place. The tabs' purpose is only to align the bearing properly in the rod bore. Regardless, it definitely sounds like 3L time.
@thenoblegeek The oil may have gotten lower than I usually keep it from being wrung out on track and burning a bit. I always kept it slightly above the full mark, but a check after the knock showed the level right at min. At this point I'm still only assuming it's a rod bearing; I'll be draining it and cutting open the filter one of these days and then probably dropping the pan to have a look around.
how did you get it home man? Drive it with the death clatter?
oggy7033 3 months ago
@oggy7033 Shanfeld trailered his turbo Miata there, so I drove that home while he trailered mine. The hardships...
bllinf 3 months ago
Unless the oil level got too low, the root cause of the spun bearing is stretching of the connecting rod and/or the rod bolts. The stretching of the rod results in loss of the clamping force that anchors the bearing sleeve inside the bore. Once you lose that, the bearing will spin because the tabs are not strong enough to hold it in place. The tabs' purpose is only to align the bearing properly in the rod bore. Regardless, it definitely sounds like 3L time.
thenoblegeek 3 months ago
@thenoblegeek The oil may have gotten lower than I usually keep it from being wrung out on track and burning a bit. I always kept it slightly above the full mark, but a check after the knock showed the level right at min. At this point I'm still only assuming it's a rod bearing; I'll be draining it and cutting open the filter one of these days and then probably dropping the pan to have a look around.
bllinf 3 months ago