<VV> How about the cooling fans from these engines?

[jvhroberts at aol.com]

 Well, not quite. Unless there's a major change in flow regime, which usually requires a Reynolds number of 4000 or more (and we're nowhere near that), the square law applies. 
Double the pressure, and you'll get a 41% increase in air flow. If it's more turbulent, great! You want turbulent flow in heat transfer applications. 
By the way, the thermostatic doors just speed up warm up. They are almost always wide open after that. 
And the fan, well, it was designed for an 80-95 HP engine, and that's about it. A turbo Corvair can't sustain full throttle for very long at all before it's overheated. Hence the buzzer on the Spyder/Corsa models. 

Sorry, to say high performance Corvairs are adequately cooled is just not true. They need more. To say the stock fan is adequate for high perf apps is also just not true. At 20% efficiency when we REALLY need it, there's obviously a LOT of room for improvement. 

That being said, deflashing, leaving off the lower shrouds, and all the other stuff one can to to improve air flow through the engine can only be a good thing. 

 

John Roberts
 

 

-----Original Message-----
From: Mark Durham <62vair at gmail.com>
To: jvhroberts <jvhroberts at aol.com>; BobHelt <BobHelt at aol.com>; jaysplace <jaysplace at laserpubs.com>; virtualvairs <virtualvairs at corvair.org>
Sent: Wed, Jul 31, 2013 11:45 am
Subject: RE: <VV> How about the cooling fans from these engines?


Bob is correct. The design of the Corvair head and cylinder fins are
made to flow a certain cfm air at a certain pressure differential
across the fins. I used to design engine and intercooler air inlet's
for aircraft engines. Just providing more pressure may not work because
of fin design and spacing. too much pressure can stall the air, create
turbulence above the cylinders and create hot spots. What may be more
beneficial, for the racing environment, is to find that sweet spot for
pressure differential and supply a consistent supply of cooling air at
the right pressure. The Corvair fan provide this and the
thermostatically controlled air exits keep the engine at a uniform
consistent operating temperature. The system works phenomenally well
considering the inconsistent RPM's and power settings the engines
experience!
Mark Durham 62 Coupe 4 speed Red/Red.
Hauser Idaho

Sent from my Windows Phone
From: jvhroberts at aol.com
Sent: 7/30/2013 19:04
To: BobHelt at aol.com; jaysplace at laserpubs.com; virtualvairs at corvair.org
Subject: Re: <VV> How about the cooling fans from these engines?

 There is a square thing going on, meaning it takes 4x the pressure to
double the air flow. But it will double the air flow, so...



John Roberts




-----Original Message-----
From: BobHelt <BobHelt at aol.com>
To: jaysplace <jaysplace at laserpubs.com>; virtualvairs <virtualvairs at corvair.org>
Sent: Tue, Jul 30, 2013 10:52 am
Subject: Re: <VV> How about the cooling fans from these engines?


Jay,
I meant that increasing the air pressure just isn't effective  in trying to
force more air past the current openings in the engine since the  blockage
to the flow results in a diminishing return for a pressure  increase.
Regards,
Bob Helt


In a message dated 7/30/2013 12:17:00 A.M. US Mountain Standard Time,
jaysplace at laserpubs.com writes:

On  7/29/2013 8:44 PM, BobHelt at aol.com wrote:
> Oh come on now!!  That  isn't a fan problem. That's a  problem with the
> heads and cooling  surfaces. A fan capable of developing greater  cfm
and/or
> greater  pressure just isn't going to force that much more air thru  the
heads
> and/or rest of the engine.
> Regards,
> Bob  Helt
>

you mean that a greater pressure differential  won't flow more air?
Or that more airflow wouldn't increase heat  transfer?


-- 
Jay  Maechtlen


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