Can LPG damage head cylinder?

Liquified Petroleum Gas or any fuel can damage the engine if it runs too lean. Lean fuel conditions burn hotter and tend to detonate more frequently. typically this condition has to continue for a while be ignored for the damage to be done..especially with LPG, caused by its lower BTU content.

Usually, LPG is better than gasoline..leaves no deposits, and oil lasts a long time. BUT..if you change a gasoline engine to LPG, you have to change the exhaust valve seat and valve to let for the lack of lubrication it'll experience. typically, a stellite alloy for both. you may be able to verify this by contacting Jasper Engines Inc. They have custom experimental engines they build for customers for alternative fuels...even hydrogen.

certified master mechanic.

Well if it goes in as a liquid it can damage the engine not the head but more of the crank, connecting rod and or piston, but gas may be compressed so no. You can not compress a liquid