<VV> Corvair Fan

[Ron]

Very good and very logical, in my perception.
RonH

----- Original Message ----- 
From: "Crawford Rose" <crawfordrose at msn.com>
To: <virtualvairs at corvair.org>
Sent: Sunday, July 10, 2005 11:37 AM
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
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