<VV> Corvair Fan

[BBRT]

I heartily agree.  If we are concerned about high performance above the 
original design of the Corvair cooling system, then the discussion should be 
on Fastvair as that is the place for high performance issues.

Chuck S
BBRT
----- Original Message ----- 
From: "Crawford Rose" <crawfordrose at msn.com>
To: <virtualvairs at corvair.org>
Sent: Sunday, July 10, 2005 2:37 PM
Subject: Re: <VV> Corvair Fan


I am somewhat concerned about the uninformed comments about the Corvair 
cooling fan. Perhaps because I went through some of these same earlier 
misconceptions myself, its hard to be too critical... however, certain facts 
are evident. The design was not subcontracted. The fan was not cheapened for 
"profit". Nor was the fan a balancing act of goodness versus cost.  The fan 
was the subject of much Chevrolet R&D in designing the fan for the first 
production six cylinder auto engine. If one reads the Corvair SAE papers, he 
or she can see the photos of the prototype fans and shrouds tested as 
published there and in the Ludvigsen photo fact book.

The fan is perfectly capable for the 80 hp engine for which it was designed 
and is stated to be overdesigned for that task by 20 per cent; that engine 
is not known to overheat at wide open throttle.  The fact that the 140 hp 
heads and turbo heads are making 150 percent of designed horsepower and 
cannot be cooled adequately does not cast a poor reflection of the original 
design.  In fact, in most foreseeable use conditions, even those high 
performance heads will typically not overheat or valveseats fail because of 
the fan performance but rather because of long term aluminum erosion and 
fatigue from detonation.  The 140 seats are just too big - that two large 
seats are proximate to one another with insufficient aluminum between them 
to anchor the seats is what is improperly designed - not the fan. The only 
beef I have is the difficulty of changing the fan bearing but, once again, 
that is a maintenance issue.

I think that we should all face the fact that we are agitated at having to 
fear belt loss and the agony of having to change fan belts at an 
inconvenient time.  We resent it because we perceive that Volkswagen and 
Porsche do not have these fan performance  problems. However, as a former 
911T owner I can tell you that those engines do overheat in high performance 
use and the axial fan was not adequate for the 2.4 liter Porsche's cast iron 
cylinders.  I never flipped a fan belt in the Porsche but those (two belts) 
did slip and required periodic tightening. Further, the late model magnesium 
fan system seldom flips its belt and  Lon's new tensioner may have 
permanently changed the way that we resolve that issue even for the heavy, 
early fans.

Finally, what car doesn't have fan belt issues? I had to change my 1.8 liter 
Golf and Cabriolet AC/alt/waterpump belts frequently (every 25k) and that is 
much more involved than the Corvair. I find that most of this discussion is 
creating a problem that doesn't really affect most of us with properly 
maintained cars.

Crawford