Steven,

The aluminum liner will expand at the same rate as the piston, with less chance of the piston gaulding or excessive wear when the engine is first started. The plating process on the aluminum liner is the same as on Mercury Race Outboards called Nikasil. This is a material like chrome that makes the liner very hard and will last a very long time if taken care of .. The brass liner is a little heaver and does not expand the same as the piston, Once the Engine is up to operating temp everthing is fine, the reasion you need to let the motor warm up !!

Dave..