Bought an 88 na s4, smoked up on startup then stopped. Oil pressure was all over the place but mostly at 0. Sludgy oil all over my engine bay. I unstacked my short block this weekend and immediately saw pieces of the oil control ring. Now I had trouble removing two of the 18 tension bolts and slid the iron up trying to remove them and then tried to close the iron again and heard some popping but didn’t sound like shattering. What other damage can a shattered oil control ring cause to the rear rotor

 

I've generally only seen oil control rings broken like that due to sustained overrev on 'meh' balanced race engines. I'd confirm the weights of the rotor on a gram scale if you're not planning on actually getting the rotors balanced.