[DeTomaso] Coating Pistons

[JDeRyke at aol.com]

Coating do work, but thats not the end of it. First, many of the coatings 
cannot reliably be applied to used pistons- the coatings don't bond well even if 
sand-blasted, and since some are ceramic, that stuff does not belong in an oil 
pan! So you may need brand new pistons to start with and the manufacture then 
applies the magic stuff in a computerized oven- for a price. They use 
ceramics on piston crowns, teflon or similar stuff on piston skirts, anti-wear 
coatings on gear teeth, bearings & cranks -there's a different coating for every 
component. Some race teams swear by coatings, but I suspect street guys never get 
that close to the edge to need coatings or benefit from the 5 extra horses 
they might free up. 
I also remember one engine builder trying several different piston crown 
coatings for a magazine test some years ago, and had a total engine failure on the 
dyno- the coating resisted high temperature just fine but the enormous heat 
of combustion (with nitrous and apparently a slightly lean mixture) melted the 
aluminum pistons underneath, until the coatings simply caved in for lack of 
support! They found drops of melted aluminum dingle-berries in the pan; why the 
oil supply didn't catch fire, they couldn't say.  
Smokey Yunick used to drop his oil pan & carefully examine the undersides of 
the pistons after a tuning session- when the oil began to look charred 
underneath the crowns, it was time to richen up, back off ignition timing or get 
another engine ready to go in....

If you do go with engine or transmission gear coatings, write up your 
experieces for the newsletter- I'd be curious what advances have been made! Good 
luck- J DeRyke<BR><BR><BR>**************************************<BR> See what's 
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