WHAT CAN CAUSE PISTON SKIRT SCUFFING UNDER THE RINGS ON RACE ENGINES

Piston scuffing under the oil ring in a race car engine is primarily caused by a lack of proper lubrication or overheating, both of which reduce the critical clearance between the piston and the cylinder wall, leading to metal-to-metal contact. Other contributing factors include abrasive contamination, such as dirt or debris, incorrect piston-to-cylinder clearance due to machining errors, and worn or damaged piston rings that fail to seal properly.

Inadequate Lubrication

Low Oil Pressure/Level:
A worn oil pump, blocked oil galleries, or a low oil level from leaks or poor maintenance can reduce the oil film, resulting in direct contact.
Oil Contamination:
Fuel or coolant dilution of the oil can reduce its lubricating properties and contribute to scuffing.
Poor Oil Quality:
Using low-quality or incorrect viscosity oil can lead to oil breakdown and insufficient lubrication at high temperatures.

Overheating

High Engine Temperatures:
Excessive heat expands the piston, reducing the designed clearance between the piston and the cylinder wall.
Cooling System Issues:
Cooling system failures, faulty thermostats, or clogged radiators can lead to overheating and subsequent piston expansion.
Oil Film Breakdown:
High engine temperatures can also break down the oil itself, increasing friction and reducing lubrication.
Ron length being short vs long causes side pushing during rotation