wrote:
On Jan 14, 11:10 am, "Peter Dohm" wrote:
wrote in message

...
On Jan 13, 10:06 pm, "Peter Dohm" wrote:

At the obvious cost of proving myself a heretic regarding VWs....
We could go back into the old debate about whether a nearly stock VW
engine
could be a reliable 50 to 60hp powerplant with the right sort of pressure
cooling system. With all due respect to Bob, a/k/a Veeduber, I am still
convinced that it can
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Mybe it CAN. All I'm saying is that it never happened for me and I
gave it a pretty good go. Failures ALWAYS pointed to excessive
heating/lack of cooling.


Doubling the velocity of the air through a given cooling fin design only
gives a 60% or so improvement, but of course, the cost of accelerating
that air is operating on a curve going the opposite direction, i.e. it
takes 300% of the energy. Low horsepower designs use thick short
widely spaced fins with a turbulent air stream for the most efficient
cooling (i.e. least power) The fact that these are cheaper to build just
happens to work with the model that low horsepower designs are applied
to. The longer a fin is, the less efficient it is. So the VW head needs
more fins, not just longer fins, or even more air. All of this is
exacerbated by the fact that as load goes up, the percentage of heat in
the cylinder head vs the cylinder itself goes up disproportionately.
Same thing happens with RPM. So punching them and revving them to get
more horsepower just highlights the limitation of the original design.
I can of course cite sources for all of this, but real engineering
textbooks are frowned upon, so to go with the flow, I will ascribe it
all to a friend of my cousin named Mackerle and his partner Liston who
has been building these things for years and stuff and knows all about
it.

Charles