Fan Shroud Modification Question

[dmilla]

I have a late model FI Fan Shorud with a Venturi Ring that I'm modifying by removing the heat snorkles. I would have gone with a 73 Thing Shroud, but I didn't like the prospect of paying over $200 for one. I've done my homework by reading the following "Sticky": http://www.thesamba.com/vw/forum/viewtopic.php?t=153387

Questions:

1. Could I cut the 1.5" compensation holes through the vanes leading back to the interior of the shroud - cylinders?

2. If I need to cut the 1.5" compensation holes exiting the fan shroud, any problem with cutting the holes in the back or side of the shroud so they're hidden?

Jake Raby, you out there?

Thanks in advance for your advice!

_________________
Experience is recognizing a mistake when you make it again...

[hoghead]

Great timing as I am trying to figure out the same thing

BTW, where to buy the venturi ring and does it provide a noticeable drop in temp?

[pupjoint]

[pupjoint]

[Glenn]

[LittleThunder]

http://www.thesamba.com/vw/classifieds/detail.php?id=545355

[AlteWagen]

This is my take on the whole fan shroud mod thing.

The so called facts:

- heater ducts from the factory need air flow to continuously flow thru to help cool the heater boxes when not in use

- if the ducts are welded shut the air flow inside the shroud is interrupted and does not flow as it should due to the "funnels" to direct air to the heater, thus the hole is needed to mimic the factory bleed off

- thing shrouds have different directional veins inside that are more "blunt" than regular DH shrouds

- thing shrouds have the 71 bus "scoop" for the oil cooler to get more air thru the cooler compared to regular DH or Puma shrouds. (raby stated the scoop type causes increased temps on the #1 cylinder compared to regular DH negative duct)

- Puma and thing shrouds that do not have heater ducts. there are no internal directional veins to direct air to these ducts since they do not exsist.

I think if you want to modify a regular DH shroud and remove the external ducts you MUST also remove the internal directional veins for the heater ducts so you do not disturb the air flow within the shroud. If the internal veins are removed you will not have to drill the hole as well.

Raby was not able to test the Puma shroud back in the day so there is no lab data to tell how effective they are compared to other OEM shrouds. He did say the difference between the thing and regular DH shroud were so minimal that it was not worth the expense.


I think this guy has the right idea.

http://www.thesamba.com/vw/forum/viewtopic.php?t=2...p;start=78

the only thing I would do different would to remove the right and left side heater ducting completely rather than redirect it to the cooler. If I made the type IV cooler conversion it might be worth it.

[hoghead]

My climate in CNX is similar to yours in KUL
Did you notice any drop in temp with t e venturi ring

[Unkl Ian]

[pupjoint]

[dmilla]

I picked up this shroud cheap, so the fact that is was an FI model with an intact Venturi Ring was a plus. I'm confident the VW engineers had a very good reason for adding the "Venturi Ring" to the late model fuel injected engines to improve cooling. Here's the guy who supplies Venturi Rings that you can weld onto your fan shroud:

http://www.thesamba.com/vw/classifieds/detail.php?id=545355

Awsome Powdercoat also sell cylinder tin air deflectors that you can weld into your to cylinder tins - just like the FI cylinder tins:

_________________
Experience is recognizing a mistake when you make it again...

[Glenn]

[dmilla]

Glenn:

Thanks for the correction regarding the cylinder tin deflectors. Any comment on my original question regarding positioning of the 1.5" compensation holes?
_________________
Experience is recognizing a mistake when you make it again...

[tncsparky]

what about if you cut your holes on the inside where they are blocked off under the heater snorkels? This would allow the heater air to continue on to the cylinders. I plugged mine and drilled a 3/4" hole in the plug.
_________________
"My Daddy told me, son if your stupid today you will be stupid tomorrow"



scotth17
I think you are just waiting around for a high-five from a unicorn so you can feel better about yourself

[dmilla]

That's my 1st question:

1. Could I cut the 1.5" compensation holes through the vanes leading back to the interior of the shroud - cylinders?

Jake Raby, you out there? Please help with your advice...
_________________
Experience is recognizing a mistake when you make it again...

[tncsparky]

i think the 1.5" hole measurement from the sticky is a typo. Others have said it should be 11/16".
_________________
"My Daddy told me, son if your stupid today you will be stupid tomorrow"



scotth17
I think you are just waiting around for a high-five from a unicorn so you can feel better about yourself

[jbreddawg]

I bought this http://cbperformance.com/catalog.asp?ProductID=1523 and added the venturi ring I cut off my FI fanshroud (the shroud was pretty beat up) then had it powder coated. I figured it would probably be better then trying to modify what the factory designed.

_________________
The wheel may be turning but the hamster's dead !

[AlteWagen]

I have the same puma shroud and if you look closely at ti it has the bosses for the heater ducts on the outside. The factory just did not add the inner diverter and did not punch out the exit hole and weld on the outer duct. This shroud is what caused me to think of removing the inner diverter.

I also have a brazilia shroud that is the same as the puma shroud but with the heater ducts installed. The only difference is the inner and outer pieces for the fresh air ducting.

If your FI shroud was cheap and you want to keep the overall cost low just drill out the spot welds holding in the inner diverters.

On a side note, it looks like your FI shroud also has the "peanut" slot for the cooling air that goes to the oil cooler. I will be doing back to back experiments with a standard FI shroud and the puma shroud. I want to measure CHT and oil temps. Then I will add the venturi ring to the puma shroud to see the difference that the ring itself makes.

[dmilla]

derluftwagen:

Thanks for the advice. Are the spot welds for the heater duct vanes obvious? I like the idea of simply removing the inner heater duct vanes vs. drilling 1.5" compensation holes in the shroud.

Please keep us posted on your test results regarding the addition of the venturi ring to your Puma Shroud on Oil & CH temps.
_________________
Experience is recognizing a mistake when you make it again...

[hoghead]

Still confused on how to approach removing the heater outlet

I think if you want to modify a regular DH shroud and remove the external ducts you MUST also remove the internal directional veins for the heater ducts so you do not disturb the air flow within the shroud. If the internal veins are removed you will not have to drill the hole as well.

Any pics of the internal directional veins that need to be removed?

If this vein is not removed can the hole be drilled in the rear of the shroud and what size of hole