As many of you may know, I have been posting videos about two all new cooling systems I am developing. I'm calling them Evolution One and Evolution Two, and I chose the name based on the fact that they are an evolution of the OEM VW cooling system. They don't introduce anything radically new, but work with all the existing cooling tin as is, for the most part, and instead just focus on how to increase airflow, as well as maintain balanced airflow between both cylinder banks, as the OEM VW Doghouse cooling system does (by the way, the pre-'71 cooling systems did not have completely balanced airflow between the cylinder banks).
I have come far enough along in the development and testing to talk about them more specifically, and reveal my early test results.
n designing these new cooling systems, my main focus was on simplicity of design, utilizing all the existing cooling tin without modification, having near perfect airflow balance between the two cylinder banks, and substantial increases in the overall cooling capacity. With these as the goals, I set out to create the fan shroud first, and the trickiest part is making sure the airflow is uniform between both cylinder banks.
Airflow in a closed system, like a fan shroud, is quite interesting, and I discovered with my earliest ideas that the air loves to swirl in the direction of the rotation of the fan. This leads to challenges in making the same amount of air flow to one side of the engine as the other. The other factor is that the fan is offset to the 1/2 cylinder side, making it want to go that direction even more.
If you just have air vanes that try to split the air 50/50 by having something at the top center of the fan, you get at least 24% more air to the 1/2 cylinder side versus the 3/4 cylinder side. So, with that as a starting point, I iterated over a number of different air vane designs with different spacing and placement. It took me around a dozen iterations to get it right, and my second to last iteration I actually had more airflow going to the 3/4 cylinder side! In the end, with what I learned from the previous two iterations, one where I was still imbalanced to the 1/2 cylinder side, and one where I was imbalanced to the 3/4 cylinder side, gave me the data I needed to split the difference and get the balance spot on. Once I had the airflow balanced, I moved on to the fan.
Starting with my "Next Generation" lightweight cooling fan, I already had about a 42% increase in airflow vs. the best that a Doghouse fan shroud can do. This is because I was able to increase the inlet size of the fan shroud reducing airflow restriction. I have since taken my lightweight cooling fan NG for Doghouse, and optimized it for the Evolution fan shroud, and I'm above 46% increase over the OEM Doghouse fan shroud. I was actually expecting a much smaller increase, because I figured the static pressure of the cooling fins and small passages would not allow that kind of increase, but I was happily proven wrong. I've mentioned both an "Evolution One", and an "Evolution Two" cooling system, and the Evolution Two cooling system uses the same fan shroud but a unique fan design, along with a second inlet.
A second inlet? Yes, you read that correctly. What I have done is take inspiration from the Porsche Type 547 engine. This was an engine that was developed by Porsche for Formula 1 racing, but was also designed to fit in the Porsche 356. It was a flat four with dual overhead cams, and was also used in the Porsche Spyder. Very few of the engines were made, and very few are in existence today, but it used a center mount fan shroud, with air inlets on both side and a fan that was two fans placed back to back to each other. For cost purposes, and to reduce manufacturing complexity, I chose to create a design for a second inlet, replacing the backing plates, and a double sided fan. You can see my most recent prototypes in the images below:
Preliminary testing results are really good with this idea. Again, through replacing the backing plate with an air inlet and velocity stack, I have reduced air intake restriction in such a way that the two smaller back to back fans outperform the one larger fan for the Evolution One!
This is really exciting, as it further increases cooling capacity, but still uses the same fan shroud, keeping complexity and manufacturing costs down, which means I can charge less for this, and the cooling capacity is incredible, and will probably get better, as I still have some enhancements to the fan that I can make and test. I'll post updated test results when I have them, but the following are what I have right now.
The test results require a bit of explanation, but the airflow results are simple to understand. Here are my standard graphs for airflow, air speed and pressure in inches of water. The air speed and pressure will seem odd, but I'll explain.
In looking at the above graphs, the first bar is the baseline best of the OEM VW Doghouse cooling system. The next is the same with a velocity ring, and then you have the Lightweight Cooling Fan NG without and with a velocity ring. The light green bar is the Evolution One cooling system, and the dark green is the Evolution Two.
As you can see, the Evolution One increases airflow by 46.9% and the Evolution Two increases it by 66.43%! These are huge increases in airflow, but you might be wondering why the air speed and air pressure are lower than the best air speed and pressure from the Doghouse cooling system with my Lightweight Cooling Fan NG.
The answer is actually quite simple. When you increase the area of the inlet, as the Evolution One and Two fan shrouds do, it takes a lot less air speed and pressure to produce the same airflow (CFM), or in this case more airflow, and a lot more. The air speed and pressure is also measured a large distance (some 1000 mm) from the inlet, so the air speed and pressure inside the fan shroud is actually still a lot higher. To keep things simple, more airflow equals more cooling capacity, and that's what we are after.
So, in conclusion, I'm very excited by the testing results, and I will be finalizing testing on my 2324 cc test engine fairly soon, and hope to get started manufacturing these in the new year. It may be awhile, but I'm hopeful I can hit the first quarter for these to start shipping. We will see. Every time I think I'm going to be able to finish a product in a certain amount of time, something prevents that from happening, so I'll post updates as I get close!