[TR] T3/4, fan,extension

[Randall]

> If you keep the engine revs below the 5000 RPM redline there 
> is no reason th install a harmonic dampener.

Just to second what TeriAnn said, I have run for many years and likely over
200,000 miles (although not all on the same engine) with no mechanical fan
and no extension, and never broken a crank.  

But these were nearly stock street motors, and rarely saw 5000 rpm even
during the occasional autocross.  I do believe the problem is real though,
so when I build a motor that will still pull strong out past 5000, it will
have a dampener.  Since it will still be mostly a street motor, I view the
dampener more as cheap insurance than an absolute requirement.

One thing I will warn about, though, make sure that whatever you use instead
of the extension pulls up only against the pulley hub and not against the
end of the crankshaft.  My first conversion worked fine with just a big flat
washer, but on the second one, the washer hit the end of the crank and only
applied a little force to the hub.  Over time, the hub worked back and forth
against the key, wearing the hub and crank and eventually tearing up the
key.

-- Randall