36hp Doghouse shroud vs late model Doghouse shroud

[Lateral]

Hi guys

Ok, firstly, do I have this accurate...there are basically 2 types of doghouse shrouds. A version based on the 36hp shroud that is quite round and the later version of the doghouse shroud that is wider at the top than the 36hp doghouse version.

Which is better and why????

Best Regards
Greg

[Marc]

What's inside the "36HP"? The stock shroud contains vanes which direct the air over the heads (the airflow coming off the left side of the fan needs to turned and redirected - otherwise pressure is the determinant, and too much of the output is wasted at the base of the cylinders).
The better "36HP" shrouds do have vanes, but they've got a reputation for coming loose. Jake Raby has done instrumented dyno testing with various fan housing configurations; I don't know that he's ever publicly revealed which was best but I'd expect it to be the stock item with the vaned "36HP" a close second. The latter certainly does give a lot more room for dual carbs if you don't need freshair outlets.

I use quotes because a true 36HP shroud won't fit on a 40HP-up case without chopping a sizeable notch out of it at the center - what this style of shroud is actually based on is the early NFA 40HP.

[Lateral]

Hi Marc,

I'm building a 2054cc motor with a set of dual throat intake manifolds and throttle bodies and I have what I thinks is either an aftermarket 36hp Doghouse shroud with internal vanes and was curious as to the difference between the 2. I found this link with come good information. http://offroadvw.net/tech/brad/fanshroudtech.htm

Thanks
Regards
Greg

[Marc]

Yes, that's a nice cutaway view of the doghouse vanes - they also take a wider fan and have a dedicated slot to feed air to the cooler. Non-doghouse (AKA "singleport") shrouds have some vaneage too, but there's an open cavity where the cooler lives - with the cooler removed, there may as well not be any vanes.
Here're some other pictures of stock shrouds...

36HP (note the contour at the center where it meets the case): http://images.thesamba.com/vw/classifie ... 647518.jpg

Early NFA40HP, commonly misidentified as 36HP. Came on "bastard" `60 bus engines and early `61 Beetles: http://images.thesamba.com/vw/classifie ... 771775.jpg

Late NFA40HP (with "hips") used from `61 through early `63: http://images.thesamba.com/vw/classifie ... 602950.jpg

Gas-heater Thing (doghouse without freshair outlets): http://images.thesamba.com/vw/gallery/pix/125024.jpg

Brazilian Puma (similar to low-profile industrial engines): http://web.archive.org/web/201001040311 ... uctID=1523

[Lateral]

Hi Marc

I'm a bit confused...the link to Dog House Shroud - Brazil Non Fresh Air Low Profile - OEM on the CB Performance website....is that an "old" version of the CB website????

I can't find the item on http://www.cbperformance.com

Regards
Greg

[Marc]

Yes, it's a cached page from Jan 4 2010 (see the "web-archive.org" in the URL?) acquired using the Wayback Machine.

[shepherd]

The "Scat" brand 36HP style with doghouse oil cooler have the vanes, fit well, and work fine, in my experience. The oil cooler tins themselves needed a bit of trimming and tweaking to fit perfectly. The shroud gives you a bit more room in the engine bay when fitting and working on dual carbs.

[Lateral]

Thanks guys

Regards
Greg