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Decided to do a test on this. The centermount shrouds have been out of the scene for awhile. Which is understandable due to bad or uneven cooling. I'm also familiar with Jake Raby's tests etc.

Anyhow, I like the symmetry the centermount makes to the enginebay so here it goes.

Done some research and studies mostly in how the internals look on 356 4-cam shrouds. And then just had a brainstorm in how to convert the same inside the centermount shroud.

So, I purchased a locally made shroud that basically is identical to the ones seen on the aftermarket today too. Did some simple tests with it as it was and came to the conclusion that the airflow indeed was very uneven... On the right side it did blow some downwards but on the left side it mostly tried to blow it all tangential to the bottom of the fan. In other words straight to the right...



So, after the 4-cam shroud studies I did this first schematic drawing.



IMO it looked good...

So, I took som milkpackages that I cut and shaped them accordingly and fitted inside the shroud.





Mounted the alternator and fan. Then pulled the fan to rotate and to my surprise the shroud blowed even stronger on the right side. And also the left side now blowed downwards as strongly as the right side.

Next was then to make the same vanes in aluminium.



I've now prefitted them and also cut out the venturi out of a stock shroud that I will be riveting to the inside. This should help the fan to suck the air better.

that is very nice work, what are you using to meaasure the airflow?

Thanks. No, measuring equipment. Relaying on my gutfeeling, designers eye and batchelirs degree un enguneering.. (Well. Almost graduated.. Never done the master thesis.. )

The airflow in just the separate shroud is difficult to measure as it only is a part of a larger system. All I can check in this form is that the direction is correct and volymes same on each side. As you can see, I have devided the fan circle in two halves. The lower half is directed to the left and the upper to the right. If you look at the DTM Jake have developed you can see many similarities to his. Mine is flat as stock type-1 though where as his is slightly offset for each side.

Also the 356 carrera 4-cam shroud is very similar to what I have done.

cheap and easy way to measure the airflow direction and strength is an old method.
long pieces of yarn attached at regular intervals around an in the output openings.
Mount it upside down, with the output facing up.
Make sure all of the yarn strands are cut to the same length, and check the length of yarn that is straightened by the airflow.
spin the generator/fan shaft at a constant speed (cordless/air powered drill motor etc etc)

Not scientific, and not exactly measurable, but it will tell you a bunch about airflow amount and direction on one side relative to the other

Hi Hebster,

We're also developing a centermount housing here. Keep in mind the original 547 twin-fan housing also brought in air from the front, so the factory ducting is not exactly right for our single-fans. Here's the studies we've done on air flow.

FJC

I MAY have a few manometers I won't need for awhile... (0-5" WC scale, ideal for fan shroud work)
I picked them up surplus, need to figure out where I packed them away.

They may be differential units, which are literally made to measure pressure balance in ductwork, which is really what you are doing.

A diffuser over the jugs (or perhaps some T3 cool tins--- on top) might help--- the heads need the lions share of cooling.

FJCamper: Nice to see others having same ideas!

If you look at both the 4 cam and the 30hp housing you posted, you can see that the corners of the vanes on both devide the fan in two same size halves. The stock shrouds are also closed under the fan so air flows better past the case and oilcooler. A shroud with thermostate flaps is as much closed below the fan as in my version. No need to create unessesary turbulence above the case. I also have the upper corner a bit higher so I get appr. same size tunnels to both sides.

Mine is also designed for oilcooler delete. In other words. Mine needs external cooler.

Edit: I realized why you dont have a paper vane in the bottom. Your shroud probably have a bottom under the fan allready? I cut out mine as it was "wrong" for my design...

Edit 2:
Added a vidclip:
http://youtu.be/nLv29y3_ntI

Hi Hebster,

Actually, I'm experimenting with the centermount for mod to both Type 1 and Type 4 engines. We road race long enduros (7 to 14 hours) and this a very serious project. Before modifying the centermount shroud, I tried everything I could think of with the 36HP shroud system.

But neither my Type 1 or 4 applications will be dual fan. I think I can achieve dual fan air distribution with vanes and guides.

You have done an outstanding job, and your intake volute is excellent. You've made a good design even better.

FJC

This kind of work could probably be able to salvage one of the SACO T4 glass center mounts.
(rather, make it actually effective cooling)

Someone here has one...

Thanks for your support!

Here's a few photos of a cut up Doghouse shroud where you see how the oilcooler foot(adapter) blocks some of the channels and also is a continuance of the bottom of the vane. All air is forced through the two flap mechanisms only. (This is shroud is an other project I'm working on.. )

I'm planning to put a centermount shroud on my trike this winter, for cosmetic reasons. The frame layout pretty much precludes installing dual carbs so I plan to mount a single 2-bbl on the "wrong" side of the fan housing. I'm well aware of the unbalanced airflow in the aftermarket centermount shrouds but figured that a mild engine in a 1200-lb vehicle probably would survive....now that you've gone and shown how to do it "right", I'll be feeling that much more guilty about it....

Who put that breather baffle on that way?
Of the eight ways one might try to orient it, only one is correct - and that ain't it.

Go for the centermount on the trike!

The engine in the last post is a 1300 dualport head engine I've disassembled just for parts... I'm not guilty this time..

Did a simple "yarn test" with my shroud.

https://www.youtube.com/watch?v=nLv29y3_ntI

Also a friend of mine who do airflow tests virtually asked me to make a CAD drawing of the shroud and he'll test it virtually.. Here it is now in 3D...

Looks ace! i like those fans for the space it gives you.

Would you be the same guy who has the removable rear with the sliding box sections to locate it? i borrowed that idea recently... thanks if so!