[Cammer]

The subject of engine coatings must be divided into types of coatings and preparation/application techniques.

I have researched various coatings with some unexpected results.

Using an example of ceramic coated piston tops found problems with: areas of thick and thin coating, porosity, crackling and cracking, peeling and delamination, and changes to parent piston material. All of these pistons were coated by well known companies. The preceding characteristics may have some roots in the preparation/application process.

Coating supplier curing temperatures and durations affected cylinder head materials, valve seats, valve guides, and various dimensional and geometrical aspects of specific cylinder heads. A possible cause for these problems may be related to exceeding design limitations of parent materials and attendant assemblies.

Some materials touted as thermal barriers actually tested as thermal conductors! Scary!

Let us look at tubular exhaust headers. A slight loss in horsepower was found on uncoated headers allowed to form rust in the tubes and collectors. On the flipside, fully coated headers showed little horsepower gain though a slight reduction in underhood temperature was noted in some tests. Some internally coated headers were not coated on the entirety of internal surfaces.

Overall, thermal barrier coatings applied by well known companies appear to be expensive given the relatively small gains noted.

I want to leave you with something positive! Friction reducing/wear reducing coatings used on piston skirts and bearings tested very well when proper preparations and processes were used in application. When using these particular coated parts follow manufacturers' guidelines for clearancing as coatings may be damaged by improper handling.

As racers we often perceive gains in performance not actually backed up by independent testing and research. Research is important to making informed decisions! It is hard to admit things do not work when you have spent alot of money to buy them!

I am looking forward to David's article on coatings!