[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [New Search]
On 25 Dec 97, John M. Kowalski wrote:
> While painting my new cylinders with flat, heat-resistant black paint today
> (yes, I know that it is Christmas, but with no family here, it seemed the
> logical thing to do), I started to wonder why no one has stated that it is
> essential to pain the silver-colored aluminum head fins with flat black
> paint. In fact, I have not even seen anyone allude to painting the head
> fins flat back to better transfer heat. Why is this? Why paint the
> cylinder fins black to radiate heat while leaving the much hotter cylinder
> heads their natural, shiny silver-colored aluminum?
The heat transfer problem is explained by the fact that the best
absorber is also the best radiator, so black is a good color for
both. Many sources recommend using a very thin coating of thin black
paint on the cylinders, black for good emissivity, thin to minimize
the insulating value of the paint.
Many of the better quality electronic heat sinks are made from black
anodized aluminum. This would be an excellent treatment for heads,
but I don't think I recall ever seeing anyone that had done it. The
best approach would be to blacken the whole exterior of the head,
leaving the rocker box bare to avoid problems that might arise from
peeling paint. The combustion chamber is best polished silver. You
really want it to absorb the least amount of heat possible.
Jim
---------------------------------------------------------------------
Melissa Kepner Jim Adney
Laura Kepner-Adney
jadney@vwtype3.org
Madison, Wisconsin
---------------------------------------------------------------------