<VV> Electric cooling fan results
BobHelt at aol.com
BobHelt at aol.com
Sun Jul 29 09:36:25 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.
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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