By Jake Raby
The Vintage VW
engine is of course "Air Cooled" and in this article I will
share with you some aspects on cooling that are imperative to comprehend
before one can ever begin to understand the ins and out of the cooling
system. I will also share with you my findings in recent tests and how
they may affect your engine.
I will begin with a lesson on the VW Type I engine. Most people do
not realize that the VW engine was always designed to be ran with
heater boxes. You see a lot of cars running in the summer with the
heater boxes in place, but with the heater outlets on the shroud blocked
off. When I see this at a show or function I ask the owner "Why
did you do that?" More times than not the answer is "To
make it run cooler since I don't need heat". I then attempt to
share with them, what I will now share with you. If you look closely
at the heater boxes you will notice that just above the area where
the hot air escapes there is a small vent. This vent is designed to
allow air to escape the heater box when the heat inside the car is
not being used. The heater box is a huge thermal radiator that takes
exhaust heat and harnesses it into its shrouding. It is not uncommon
for a heater box to be 500 degrees!
|When VW designed this
system, they knew that in the summer the heat would be turned off,
but that the heater box must still remain cool or else the heat would
soak into the head, making the engine run hotter. The system works
the entire time that the engine is running, as the fan is producing
air and constantly keeping a flow of cooling air through the heater
boxes via the outlets on the shroud. The small vent on top of the
heater box allows this air to be bled outside (away from the cabin
of the car, and away from the engine) when the heater was not being
used. So, common sense tells us that when the heater boxes are retained,
but the heater outlets are blocked off, the airflow cooling the heater
boxes is non existent. The end result is that the heater boxes are
as hot as a nuclear reactor. These super hot boxes are located directly
below the number one and number three cylinder heads and do a great
job of MAKING THE ENGINE RUN HOTTER, NOT COOLER, as many people think.
In short, by blocking off the cooling air, the heater boxes overheat.
Moral of this story. If you want to block off your fan housing
outlets for the summer, also remove the heater boxes!
Most of the folks reading this article have seen "Super cool
tin" glorified in publications, advertisements and the like.
This "Super cool tin" was originally used by VW on the PANCAKE
(non upright) Type III engine. Its primary goal was to enhance the
air that was being made by the Type III cooling fan, and to better
route it around the cylinders. Since the air was made by the Type
III system horizontally, instead of vertically like a Type I engine
this was a great idea. If the tin was not there, all the air would
simply blow over the cylinders and out the back of the shroud doing
little if any cooling at all. The back pressure from the more "shrouded"
lower tin made the air look for escape routes and in doing so it helped
to dissipate heat. VW ONLY USED THIS TIN ON THE Type III ENGINE, it
was NEVER used by the factory for a Type I engine with an upright
cooling system, or on the 1971 and earlier Type II engine, which was
the hottest running engines in the entire VW line up! Why??? Here's
at VW knew that it was not needed for the upright engines, and could
hamper the cooling. The upright engine did not need the back pressure
and resistance of the "Super cool tin" as its air was
being forced DOWN directly over the cylinders, not horizontally
like the Type III engine. If VW would have thought this tin would
help keep upright engines alive they would have installed it on
their hottest running heaviest load engine, wouldn't you think??
That engine was the Type II engine and it never incorporated the"Super
cool tin". I have done tests to prove that VW was correct and
that the best tin for the upright engine is the stock cylinder deflectors.
I once heard a story (from a very competent source) that in the
mid seventies right after the Type II had been removed from the
VW line up that a prominent player in the VW aftermarket world bought
all the remaining Type III tin that was left over from the factory.
This tin was sold for basically pennies because VW had no use for
it. The source got the tin, made up a marketing ploy and called
it "Super cool tin" and the name stuck. They made good
money off of it for sure, and unless people really think hard and
test the idea actually seems correct, but I have found otherwise.
Basically the air cannot escape the engine fast enough and the shrouding
creates more resistance to the air than directional positioning.
Moral of this story. There is more to cooling than what meets the
eye. Sit down and use your own mind when you are designing your
engine, and just because something is advertised doesn't mean its
written in stone. If you have the tin on your current engine, don't
be alarmed, it won't absolutely kill the engine, but it will create
where it gets interesting. My main area of interest, and where 90%
of my research has been is with the VW Type Four engine. I have
helped to educate the masses in the US with the facts concerning
this engine and its conversion into vehicles that originally housed
a Type I engine. We convert Type IV engines for all Type I vehicles,
Early Type II vehicles (late Type IIs already had a Type IV) We
even set them up for Type III applications as well as 356 and 912
Porsches. One of the biggest challenges with the Type IV conversion
is with a conversion cooling system. Recently I did a very extensive
scientific cooling system test on my Dyno to see just what systems
worked and what didn't. I did this as a test for my very own handcrafted
cooling system that is the spotlight of my newest endeavor www.massivetype4.com.
This system, as well as a Type I version, was originally designed
by the late Joe Locicero and took him 12 years to create the pair
of cooling master pieces.
In my system
tests I began with building a 153BHP 2270cc Test engine. This engine
is by far my biggest seller and is the most widely built Type IV
performance engine, we have perfected it! The engine had to be strong
enough to live for 30 hours at 5,000RPM and keep its adjustments,
as once the tests started the engine could not be altered, else
all data would be lost, and inaccurate. I was sure the 2270 would
be more than strong enough for our foundation. The next step was
to create an outline and a way to accurately log data, so I chose
to buy all new instrumentation and also to search out a few engineers
to help me design spreadsheets and an outline. This had to be scientific,
or it was a waste.
I was testing 7 different cooling systems on this same engine. The
goal was to see which systems cooled all 4 cylinders more evenly,
and which systems pulled the most horsepower. For many, many years
the 911 system was revered by many and I was ready to see just what
it had, so 5 of the 7 systems we tested were Porsche 911 versions
(axial style fan). The only radial fan system we tested was that
of my DTM cooling system. Many people think that the key to better
cooling is a tremendous amount of air with enough pressure to get
to all the cooling surfaces and help dissipate heat. What we found
was that theses huge amounts of air are only good for one thing
KILLING HORSEPOWER! The 911 fan creates enough air to cool a huge,
6 cylinder 911 Porsche engine. The 911 has 25% more surface area
than that of a Type IV, (a Type IV has 23% more than a Type I, FYI)
When the huge amount of cooling air is made, it MUST go somewhere.
If it cannot escape the engine quickly, is stagnates, does a poor
job of cooling, and creates a huge drag on the cooling fan. The
drag of the fan results in more work for the fan, thus more work
for the engine, and that equals a loss of Horsepower. I have seen
up to 29HP lost on a 239BHP engine with a 911 shroud!
found out about the 911 cooling systems was we could actually make
the engine cool better with the 911 shroud by drilling some holes
in the shroud to help move the air over the cylinders better. We
dropped the temp of the #4 cylinder 40 degrees by modifying the
shroud with a 1" drill bit in four areas! This proves that
all the air is being wasted, and is not needed. When we got to the
testing of our DTM shroud, I was amazed. The DTM only pulled 6-8HP
off the engine, instead of the 13-17 that was average with the 911
systems. Another thing that we noticed was that all the decent cooling
systems shared a distinctive whine as they produced their cooling
air. It is very strange that on a 911 engine, this whine is present
with the 911 fan, but not to the same degree when it is placed on
a Type IV. Was it that the stagnation of the air dampened the whine
since the air could not be moved fast enough over the smaller engine??????
Probably so, but no one knows. The DTM fan is retained from a Standard
Type I 1971 and later cooling system. The DTM also uses the Alternator
and pulley from a Type I. What Joe had in mind when making the system
(I talked to Joe on a daily basis when he was alive) was to create
a shroud that would correctly position the airflow over the cylinders
and heads, and to create that air with less power loss. Since the
Type IV engine is 23% larger than a Type I engine (surface area
wise) it would more effectively use the air that was created and
directed to the most critical areas. Since just enough air was being
made to do the job power losses would be less, as the stagnation
would not occur, and if it did it would not be as critical to power
losses. What he thought was correct! The testing proved that the
DTM was THE system to beat, as our head temps dropped drastically
and HP loss on the same engine was only 7 HP! All 4 cylinders remained
very close in proximity to each other and the engine revved faster!
Joe's homework paid off! it really amazed me, as I thought the 911
systems would really do well at our 4,800RPM test with a 80HP load.
But the DTM proved that it could sustain a higher load at the same
RPM and still run cooler than the 911 system.
this story. Buying a huge 911 system that produces
a tremendous amount of air may not be the wise choice that many
people make it out to be. The testing proved that more air and pressure
is not the key, but the correct air with the correct positioning
is the key- Just like Joe thought. I will be doing comprehensive
testing with the Type I cooling systems in December of 2003 and
will be seeing just how Joe's Type I DTM will fair against all the
stock systems, 3 911 systems, a Four Cam Carrera style shroud, as
well as all the aftermarket chrome shrouds. It will be the test
of all tests. The base engine is a 190BHP 2165 Type I that I'm assembling
as we speak. I hope this cooling system article has helped you to
enhance your thinking about what to believe when you open the cover
of your favorite magazine and see all the claims of cool running.Remember
that "Looks kill" and engines are primarily designed to
propel the vehicle...Keep an open mind and don't let the physical
beauty hinder your engines performance and longevity!
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