[Shop-talk] Fan Shroud

[nogera2 at att.net]

Guys, I've got a Morgan Plus 4. Several years ago I solved a low speed over
heating problem by making and installing a fan shroud ( the fan sits a good
4 inches behind the radiator).
Well I'm ready to do a version 2.0 of my shroud. The 1.0 version makes
changing a fan belt a major undertaking. On the version 1.0 I carried the
shroud to the rear so that it ended on a plan with the trailing edge of the
fan blades. What I would like to do is shorten up the shroud so it ends at
the leading edge of the fan in order to make fan belt changes easier.
The question: I know on a blowing fan the air flow is greater if the shroud
covers the fan blade tips. Is that also true for a sucking fan?  It seems to
me that air spilling off the fan tips is not going to be a problem since the
objective is to pull outside air thru the radiator and since the shorter
shroud will block air from looping back through the fan the performance
should stay the same.

What say the best bunch of guys on the internet?

Bob Nogueira ( I'm no engineer but I play one in my garage)