<VV> RE: Cooling fan improvement

[Craig Nicol]

I've converted about 20 cars (one Corvair) to EFI. I have a second Corvair
140 converted to EFI by Milt Binion.  Generally there has been about a 50%
gain in fuel economy (my '66, for example, gets almost 30 mpg on the
highway).  Several of my conversions, mostly Tri-five Chevys, went from
overheating pigs to cool runners with the change to EFI.  On the cars that
had aluminum radiators, overcooling has been an issue and on two, I've had
to cover a portion of the radiator with lexan to block airflow.  My '65 and
'66 EFI 140s run about 275 to 325 max in hot weather highway conditions.
I'm open to other conclusions, but comparing apples to apples, I've
concluded that reducing wasted fuel results in reduced heat in the cooling
system.  I understand that this subject is controversial; prior to my '66
Corvair 140 EFI conversion, I had several people tell me that "running it
lean" would cause it to overheat, but the opposite seems to be the case.
Thoughts, comments?

Craig Nicol

 

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From: JVHRoberts at aol.com [mailto:JVHRoberts at aol.com] 
Sent: Saturday, August 04, 2007 5:04 AM
To: NicolCS at aol.com; virtualvairs at corvair.org
Subject: Re: Cooling fan improvement

 

Being a turbo guy, I think the cooling system on a Corvair has a HUGE
deficit. 

Extra fuel actually loses heat, since there isn't enough extra air to really
burn it. That's how 2 stroke air cooled motorcycle engines keep from
overheating. 

When the 50% increase in fuel economy comes from lower aerodynamic drag,
less weight, and all the other things that reduce HP load, then you're
right. 

However, Porsches, the closest other example I can think of, actually had to
INCREASE cooling over the years, since the HP was constantly going UP, and
the burden from catalytic converters, standard air conditioning, heavier
cars, etc., took its toll.

 

In a message dated 8/3/2007 11:01:50 PM Eastern Daylight Time, NicolCS
writes:

Huge deficit?  I wasn't aware that stock engines had a huge deficit ;-)  Now
the recently tested electric fan, that's another story.  

 

A fair amount of engine heat is caused by engine friction.  When we ran
engines on the Honda dyno, we only had to motor the (non-running) engine on
the dyno for about 20 minutes to reach full operating temperature; that heat
is almost entirely caused by engine friction. (Compressing air accounts for
some of the heat, but much of that goes out the exhaust pipe.) The #1 source
of engine friction in a broken-in engine is the cam/lifter/valve train so
switching those components to rollers makes a big dent in engine heat.
Taller gears help too 'cause engine friction is proportional to rpm.  EFI
has a huge effect on engine heat too.  When you have a 50% increase in fuel
economy, all the heat from that extra fuel is no longer being rejected into
the cooling system and exhaust and heat loads on the cooling system go down.
All these things add up to much smaller radiators (or in our case, fans)

Craig

 


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Agreed, but it seems that all of these are marginal improvements (certainly
worth doing!) but won't close the huge deficit in cooling capacity. 

 

BTW, there's one heck of a lot more difference between the '70 PU truck and
the new one besides the 350 SBC and the LS series engines! 

 





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