<VV> Electric cooling fan results

BobHelt at aol.com BobHelt at aol.com
Sat Jul 28 22:34:22 EDT 2007


 
COOLING THE CORVAIR ENGINE
WITH AN ELECTRIC FAN


With the knowledge that the stock Corvair cooling fan consumes some 14  
horsepower at 4800 RPM, and even greater power at potential racing speeds,  
enthusiasts have long sought a remedy for this considerable reduction in engine  
output. If somehow, the stock engine-driven cooling fan could be replaced by an  
electric-driven fan similar to those now being used on current production cars, 
 then the horsepower required for cooling could be reduced. There have 
previously  been many attempts to accomplish this feat, but none has ever been 
entirely  successful, although rumors abound with success stories. Despite this, 
the  concept remains alive with the hope, that maybe there might be some way to  
accomplish this cooling feat; something previously overlooked or some new 
piece  of equipment that might do the job. If this cooling method worked, not 
only  would considerable engine power be saved, but also any potential fan belt  
problems might be side-stepped too. One of the initial problems when trying to 
 compare the stock cooling setup to an electric fan is the confusion of CFM  
ratings. The stock fan is rated somewhere around 1400 CFM at an engine speed 
of  4000 RPM, while many electric fans are rated at a much higher CFM. This 
leads  one into thinking that the electric fan might flow more air. It isn’t so, 
but  it’s easy to get confused. The problem is that the electric fans just don’
t  develop the kind of air pressures required to force the air over the 
engine  restrictions.
            At the 2005 International Corvair Convention in Portland, Oregon, 
a  company, Vairhouse, of Reno,  Nevada was displaying an electric  
cooling-fan setup they were manufacturing and selling. They not only had the  unit on 
display, but they also had a Corvair equipped with their cooling unit  that was 
being driven around the convention area. Complete engine cooling was  being 
claimed and the rumor was that the Corvair car had been driven from  Reno with 
this  unit doing the total cooling. If true, it would represent a major 
milestone  accomplishment.
            With this new electric cooling-fan system now for sale and 
available, we  decided to purchase one and run some of our own, relatively 
impartial, tests to  see how good this unit might work. As far as we know, this would 
be the very  first actual independent testing of any similar cooling setup. All 
previously  tests were, of course, run by the system designer/builder and 
actual facts or  reports were seldom released. 
            So it was, that we obtained this new cooling system, designed to  
completely replace the stock engine- driven cooling fan on a Corvair. Ken 
Hand  generously offered to install the system on one of his Corvairs and run the 
 tests. Frank Parker, a Chevrolet engineer (of Corvair/Northstar fame)  
instrumented the test Corvair for data collection and assisted Ken in running  the 
tests and evaluating the data. 
 
Bob Helt
    
 
                                                        The  Tests
  First off I  must apologize to the group for taking so long to finish this 
electric fan test.  I have had some personal problems in my life along with 
trying to run a  convention. BUT, the electric fan test has finally been 
accomplished! Among  other things, I lost the use of the car that we started the test 
with and the  owner wanted nothing to do with any of the testing. We did get 
base line testing  done on the first car so we have 2 cars with base line 
tests. I think the  comparison of the results will surprise you when you look at 
the  stats.
                                                                              
                                                      
      I also  have to thank Bob Helt for supplying the fan kit. Without his 
offering this test  would never have happened.
                                                                              
                                                      
      Now,  what I am going to talk a little about are the basic tests, but 
mostly about the  kit in general and what it takes to install the kit. The base 
line tests were  very interesting. On the first car we were able to get a 
couple of different  outside temperatures and again the numbers will be 
surprising to look at, but as  I recall the engine temps change with the outside temp, 
not directly but on a  bit of a curve. With the second car base test we had a 
fairly warm couple of  days but the electric fan test day was decidedly cooler 
than the base line test.  We measured outside air temp, oil temp, head temp 
and the lower heater plenum  air temp, MAP and RPM. The oil temp was taken at 
the oil pressure switch sender  hole; the MAP was taken from the balance tube; 
the head temp was taken from a  probe that was bolted against the head boss 
where the overheat switch would  mount, and held there with a washer and a bolt; 
and the air plenum temp was  taken in the heater shroud and shielded from the 
exhaust manifold radiant heat  by the shield that is there for the thermostat.
 
      I need  to describe the cars that we did the tests with. The first base 
line tests were  done on a 1965 Monza with a 110 PG. The second car was a 
1965  Monza with a 95  PG. Both cars were what anyone would drive most anywhere. 
Specifically, the  second car - the 95 PG - was a borrowed car and as I drove 
it I was mildly  surprised at how well it ran. I hadn’t ever worked on this 
car either!  

To start  the electric fan install, of course, I had to take apart the top of 
the engine,  all the way to removing the top cover. I then trial fitted 
everything. I have to  say by the initial look of things I thought I would have 
this on in a couple of  hours. Well, after really getting into it I found out 
that the kit is not really  a complete ready to install kit! I had to fabricate a 
crank case breather; all  the tolerances were very close but did not allow 
for the differences in the  tolerances of manufacturing. I had to ream, enlarge 
or elongate almost every  hole to make things fit the way they should. The 
exception was the top cover; it  fit with no problems at all. In what looked like 
a really good piece - the  alternator mount - I really had to bend a little 
to get the alternator to fit in  the slot and then I had to elongate the 
alternator mount holes considerably. The  special bolts needed were supplied with 
the kit. The one thing that was never  really talked about was what to do with 
the dipstick. The electric fan is larger  than the stock fan and I had to 
seriously bend the tube in two directions to  gain the width needed to clear the 
electric fan. Then I had to drill a hole in  the fan housing to match where the 
dipstick tube was. I also had to match drill  where the vent tube would come 
through the fan and also figure out how to hook  it into the PCV system. Since 
this was a very stock engine to begin with, I had  to contend with a fuel pump 
when installing the idler pulley. There was no  mention of how long a belt to 
even start with so I had to use the old belt and  mark it, and then measure 
it to come up with something close. I got three  different belts just to be 
sure. The first belt was way too short and I couldn’t  even get it on because the 
idler hit the fuel pump. The other belt was way too  long and it hit the 
distributor before the belt got tight. Thank goodness I got  the third belt in the 
middle as it was just the right size. I did have to pull  the idler off the 
mounting bolt to get the belt on, but when adjusted properly  it cleared 
everything, the fuel pump and the distributor. That is a very narrow  margin to deal 
with. There was also a 12 plate cooler on the engine and I had to  trim a 
notch in the top flange of that to clear the belt. I have to say this is  not for 
the average person to try and tackle. It took me 2 long days to get the  
testing and the fabrication done on the second car. Again, the instructions that  
were sent with the “kit” were very basic and generic. Frank and I decided to  
hook the fan up with just a snap switch in the engine compartment instead of 
any  fancy relays or temp switches. We did make sure that the fan went in the 
correct  direction! As we began the test, what we did was start the engine and 
then  immediately start the electric fan.
                                                                              
                                                      
      Now for  some observations; there was a lot of air reversion through 
the electric fan  when it was running statically. In comparison the stock fan 
had NO air reversion  through the fan.  Even with the electric fan and the air 
doors  open, there was still air reversion back through the fan. Not as much 
mind you,  but there was still air reversion. 
                                                                              
                                                      
      On the  initial tests we did about 45 MPH on the secondary roads for 
about 3 miles and  then we did freeway for about 20 miles starting out at 65 
MPH; then we hit some  traffic and had to slow down a little but then were able 
to speed back up to 65  MPH and at the end just before we got off the freeway 
we sped up to 70 for about  2-3 miles. The numbers we got were very close to 
the 110 PG with about the same  curve on temps. You will find the two engines 
very similar even though they were  a 110 and a 95. I won’t cite numbers because 
that will be in the graph from  Frank. One of the common misconceptions is 
that the 110 is the worst of the two  engines for heat because of the 
compression ratio. Well, I think we can put that  theory to bed.
                                                                              
                                                      
       With the electric fan finally installed we went out for our initial 
test  and did the same thing as the previous test. It was about 45 on the 
secondary  roads and once we got to the freeway we accelerated to the 65 MPH speed 
we did  before. Let me back up a little and talk about the head temp only as a  
reference. If I recall correctly, with the stock fan the temp came up on a 
very  linear scale and then stabilized and stayed at a decent number. When we 
got the  electric fan installed and did the same tests the head temp came up 
very quickly  and not linear at all. It was almost a vertical scale until the air 
doors opened  and then the temp started to go a little more linear but the 
head temp never  stopped climbing. We had to stop on the side of the road when 
the over heat  light came on. We stopped and kept the engine at an idle and the 
temp came down  very quickly. We started out again and then got into traffic 
in a construction  zone and the temp was a bit high but stayed low enough to 
drive the car. When  the traffic cleared a little we accelerated to a moderate 
speed and the engine  temp kept going higher. We did not complete the same 
mileage with the electric  fan because the engine would not stay cool at freeway 
speeds. We got off the  freeway early and took all secondary roads back to 
Frank’s house. We found that  we could maintain 40 MPH and the temps would 
stabilize so we didn’t have to stop  and let the engine cool down. Once when we had 
clear road ahead we accelerated  to 60 MPH and the engine soon overheated 
again so we stopped for a few minutes  to let it cool then started back at our 
slow pace. We could hold 45 MPH for  quite some time but the head temp would 
still start to climb. When I backed it  down to 40 MPH the temp would very slowly 
go back down to the 40 MPH temps which  were right at the high end of the 
spectrum. So we slowly made it back to Frank’s  house and proceeded to remove the 
electric fan kit and put all of the stock  parts back on.
                                                                              
                                                      
         I think when you see the numbers you will know that this electric 
fan  does not work on a stock engine. As I said earlier, I didn’t do anything 
special  to the engine, it was an off the street engine that the average person 
would try  to do this with. I have to also add that “IF” you started out to 
build an engine  and totally deflashed everything and made sure all the 
passages were open to the  max in the head and everything was spotless with the lower 
shrouds off, maybe,  just maybe, the electric fan would cool sufficiently to 
drive on the freeway at  a decent speed. That test may happen but not in the 
very near future as I would  have to build an engine just to test the theory 
out.
                                                                              
                                                      
      To  theorize I would think that the engine would have to be very clean, 
all the air  passages opened up in the heads, no lower shrouds at all, and 
maybe even ceramic  coat the exhaust stacks and the exhaust manifold as a 
minimum. Then the fan that  was supplied may barely keep up. 
 
      Frank  Parker will have graphs available and I think I will post them 
on my web site so  Frank will not have to resend the same info time and again.
 
                                                                              
                                                      
Ken  Hand,                                                                    
                                               
Frank  Parker                                                                 
                                                    
 &                                                                            
                                                    
Bob  Helt




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