BMFC, Tiiming, and Coatings

[Robert Harris]

Dave Vizard reports that simply coating the combustion face of the intake
valve lowers the intake air charge temperature by 60 degree F or more and is
worth typically two octane numbers increase in the effective octane of the
fuel.

Remember that the intake valve face is exposed to combustion temperatures for
at least 50% of the cycle and reaches the same temperatures as the exhaust
face.  Further the back side temperature reaches 600+F in a normal engine.
The majority of the intake valve cooling comes from HEATING the intake air
charge. 

Insulating the valve from most of the combustion temperature significantly
reduces the intake valve temperature and reduces the amount of heat the valve
can reject to the incoming charge.

The intake valve coating is so important that Vizard recommends that if you
only coat one thing, it should be the intake valve.