<VV> Corvair Fan

[Crawford Rose]

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