As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAKEOFF ROLL PILOT REPORTED A LOUD POP FROM THE LEFT ENGINE AND THE AIRCRAFT YAWED TO THE LEFT. THE TAKEOFF WAS ABORTED. VISUAL INSPECTION REVEALED THE NUMBER SIX CYLINDER HEAD HAD SEPARATED FROM THE BARREL. THE ENGINE HAD 554 HOURS SINCE OVERHAUL. THIS ENGINE WAS INSTALLED ON A CESSNA 421C.