Quote:
Originally Posted by tommurphy73
There has been a lot of talk about ceramic coating the crowns of pistons to improve the insulating properties of the piston and keep the heat where it can do the most use inside the cylinder. The most commonly used ceramic as far as I am aware is aluminium oxide which is deposited on the suface and using heat is bonded to the surface. Recently I have seen some debate as to wheater these coatings are any good.
Other coatings are also available for the piston skirt which are widely accepted as being benificial by reducing friction but it is very difficult to get hard facts and numbers to substanciate the claims.
What are you guys thoughts on this?
Regards
Tom
|
The coating I use on piston crowns, combustion chambers and valves is Powerkote CBC1 or 2 depending on application and the same brand dry film lube for skirts, the aluminum oxide is the blasting media used to etch the part so that it absorbs the coating.
Then you bake it in for an hour at 300 degrees.
I have run a 350 small block Chevy on the dyno for 21 pulls with 12.5 compression.
More than half the pulls was on nitrous and the engine on the bottle made between 715 and 820 horse, the biggest shot we fed it was 300 horse plate.
The plugs were ghost white and speckled indicating lean, as a matter of fact we pushed the engine so lean that at tear down we found the top ring on #3 cylinder was broke, the ring gaps were set tight at only .024, but the pistons were perfect, as a matter of fact the underside of the piston had no color, this indicated the crown stayed cool, usually they will have a brown color to black if to hot or a big hole if way to hot.
(I put David Vizards name and the word coatings and found this at the top of 155 results.
The May 2003 issue of SPEEDWAY ILLUSTRATED has an article on "Port Volume" written by David Vizard. On pages 79 and 84 a photo of a combustion chamber appears. On page 84 it notes that it is a Coated unit. Coatings are becoming common enough that no special mention is made of them. This is a further indication as to the trend towards more and internal engine coating taking place. Keep your eye open for details such as this as it helps convince the few unbelievers remaining, of the error of their ways.)
My understanding is that coatings work so well they are becoming the standard practice to be competitive.