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its a bit that sucks BEFORE the engine blows!

Some go to great lengths to ensure the VW engine is sealed air tight.  Here's a photo of using thin foam to seal the dog house's tin covering to the shroud.  Many installations are missing the lower tin piece directing the oil air exhaust and its rubber gasket.  This allows the fan to such the oil cooler's exhaust air back into the cooling airs intake fan.

Related imageImage result for sealing the vw bug engine doghouse cooling tin

Many favor aftermarket shrouds too - many are just metal shells.  Those that have disected stock shrouds (Jake Raby had a study out years ago when he was designing his DTM shroud) found that many aftermarket ones did not have the air directing vanes of the stock ones.

Image result for sealing the vw bug engine doghouse cooling tinRelated image

Another area of discussion is the fan itself- the width, number of blades as well as balancing and welding of the blades (for higher than stock RPMs). Then there "do you add" the air velocity ring like was used in the 356 engine?

Image result for vw bug cooling fan comparisonFan Shroud Velocity Ring


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The later (1970-on) fan shrouds for the wider/larger capacity fans and larger oil cooling towers had a non-moving velocity ring riveted to the back of the housing.  Earlier shrouds had a moving velocity ring that provided less air flow when cold and more flow when warm.  Pretty ingenious, actually.  The later shrouds are not domed, like the coveted 36hp shrouds, but are flat across the top, like this:


(This is the first GIF file I've gotten to load on this site in over a year....)


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Last edited by Gordon Nichols
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