For quite some
time now our VW friends in Europe have been tapping in on the extra power
and durability of the type IV VW motor. This is the engine found in the
72 and later Bus, 411/412 car, and 914 Porsche. With the popularity of
the Euro-look cars is coming the interest in the type IV conversion in
this country. We just went to Rabys Aircooled Technology to shoot
a video with Jake Raby who is leading the way on this new trend. What
we found out is that while the type IV motor in stock form appears to
be enormous when converted to upright cooling is no larger than the type
I and slides right in. Instant double the horsepower and torque and can
easily be tripled and on and on. Here
is what it takes to make the conversion:
1. The custom upright fan shroud.
The one Jake uses and recommends (and now manufactures) is what is called the DTM (down the middle) shroud. It is designed to direct the air evenly over all four cylinders solving the notorious overheating and resultant dropped valve seat problem. Air is directed to the larger type IV oil cooler that is situated behind the shroud but uses the air much more efficiently.
The larger late model type I fan and alternator is used on a special made mounting stand that is easily attached to the top of the case.
Jake makes a special billet alum adapter to allow the use of the stock alum lower pulley.
A stock 72 to 75 bus flywheel is drilled to accept the stock pilot bearing to support the nose of mainshaft in the normal manner. (Later bus and 914 flywheel will not work.)
A custom exhaust is needed due to the different design of the T-4 heads. Jake showed us his two favorites. The Ahnendorf and the all out Tangerine racing (tangerineracing.com) headers.
These were a little pricey but Jake says the extra horsepower they make makes them well worth it.
Special tinwork is needed to snug everything up in the engine compartment. Jake has the templates if you want to cut your own or has it ready made in aircraft aluminum.
Now bolt on a set of Webber IDFs and you are done. (Actually you should install the motor then put on the carbs which is even easier on this conversion.)
Absolutely no cutting or bending had to be done to the car and the motor when converted only weighs about 26 lbs. more than the original. Nonetheless with the additional torque it is a good idea to add some extra support either to the nose of the trans or the rear of the motor or both, because you are not going to be able to resist putting your foot in it once in a while.
The extra torque also makes this set up great for the higher geared freeway flyer trans. We got a chance to drive the car we shot in the video and the engine at any speed was so responsive and smooth that it felt like we always had power to spare. It was very impressive to say the least. If you would like to know more go to one of Jakes sites at www.massivetype4.com or www.aircooledtechnology.com. We will have the whole procedure out on video by Nov. 03, 2003.
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.
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.
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
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........
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 from www.westach.com
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.
What we 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.
Moral of 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!