Reading this discussion I went to the Calico website.
Quote:
How long will the coatings last?
Calico's CT-2 ceramic thermal barrier and CT-5 oil shedding, corrosion resistant coatings are virtually permanent.
Calico's CT-1 and CT-3 dry film lubricants are "sacrificial" in nature and eventually wear out. But rather than wearing out the engine part, wearing the coating will save you time and money on expensive engine parts. It is also possible to re-coat and further extend the life of the coated parts at a fraction of the replacement cost (i.e. pistons, etc.
For my build the desire was to try to reduce temperature and have less chance of early detonation as well as reduce measures needed to reduce the chances of early detonation using pump gas. Same reason I went two steps colder on the plugs.
For pistons I chose 2618 alloy for the ductility verses brittleness of 4032 as quoted below:
There are two common alloys used in forged pistons, 4032 and 2618. Silicon-aluminum alloys, such as 4032, have great wear characteristics because the silicon particulate hardens the alloy and reduces the thermal coefficient of expansion. However, silicon-aluminum alloys can turn brittle and become prone to fracturing when subjected to extreme stress. With a piston made of a silicon alloy once a crack starts, it doesn't stop until the piston suffers a catastrophic failure. Low- or no-silicon alloys, such as 2618, may wear a bit faster but provide better strength and durability. In the rare case of a crack in a 2618 piston, the crack will migrate to an area of lower stress and stop. 2618-alloy pistons keep their shape under extreme pressures and high RPM's.
The 2618 alloy grows more with heat and does require added clearance. On my build each cylinder is .0041 larger than the matching piston. I do not expect any softness due to the ceramic coating application. Time will tell.
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