<VV> Corvair Fan

[JVHRoberts at aol.com]

140, turbo, and air conditioned Corvairs have inadequate fans on  them.
Chevy designed the cooling fan to work, and do so as cheaply as possible.  
The 64 and later mag fan is die cast, and its shape is determined by its  
compatibility with that manufacturing process, NOT cooling and HP requirements.  
Magnesium was chosen because Chevy recognized there was an inertia problem, and  
swapping magnesium for aluminum meant less mass, more stiffness, and a fan 
that  wouldn't 'ring'. But it is NOT the best way to blow air through an air 
cooled  engine. 
 
 
In a message dated 7/10/2005 2:38:03 PM Eastern Standard Time,  
crawfordrose at msn.com writes:

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
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