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Kiwi1966 Samba Member
Joined: August 18, 2009 Posts: 168 Location: Ohoka New Zealand
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Posted: Fri Nov 16, 2018 4:40 pm Post subject: Scat fan shroud with heat |
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Hi
Purchased a scat shroud with heat for a new 1776 build for my bay .Looking at the heat tubes in the shroud they are done totally different to a oem doghouse with heat and almost seem to be an afterthought. Any comments on this please- re loss of head cooling and actual effectiveness of actual output of air to the heat exchangers almost tempted to ditch this and track down a used german doghouse shroud
Last edited by Kiwi1966 on Sat Nov 17, 2018 2:36 am; edited 1 time in total |
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jeffrey8164 Samba Member
Joined: January 06, 2018 Posts: 3804 Location: Georgia
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Posted: Fri Nov 16, 2018 6:17 pm Post subject: Re: Scat fan shroud with heat |
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I can’t speak to particular inefficiencies, but will say that it’s been common knowledge for what seems like decades that aftermarket shrouds don’t perform as well as original.
For some reason the aftermarket thinks we won’t pay for a proper part and thus create things as cheaply as possible. It’s probably their business model.
Then, there is the other side of the spectrum, that claims to have a superior product at an astronomical price.
Think Raby and Concept 1.
Both have shrouds with their own claims, and as I recall sell for around $400.00.
At any rate, you’re either shopping mass market or boutique. Boutique will always cost more because they’re hand made to order in most cases and hopefully not made on Monday.😉 _________________ Volkswagen!
Turning owners into mechanics since 1938.
“Let he that is without oil throw the first rod”
(Compression 8.7:1) |
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wcfvw69 Samba Purist
Joined: June 10, 2004 Posts: 13382 Location: Arizona
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Posted: Fri Nov 16, 2018 8:00 pm Post subject: Re: Scat fan shroud with heat |
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You can find excellent, used OEM German made dog house fan shrouds for $40 dollars. There's tons out there.
Sadly, most "new" parts are nowhere close to the original parts quality. _________________ Contact me at [email protected]
Follow me on instagram @sparxwerksllc
Decades of VW and VW parts restoration experience.
The Samba member since 2004.
**Now rebuilding throttle bodies for VW's and Porsche's**
**Restored German Bosch distributors for sale or I can restore yours**
**Restored German Pierburg fuel pumps for sale or I can restore yours**
**Restored Porsche fuel pumps or I can restore yours**
**Restored Porsche distributors or I can restore yours** |
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mark tucker Samba Member
Joined: April 08, 2009 Posts: 23937 Location: SHALIMAR ,FLORIDA
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Posted: Sun Nov 18, 2018 12:17 am Post subject: Re: Scat fan shroud with heat |
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I think I removed mine or squezed them a lot closer togeather so the heads get better flow....or not. |
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Kiwi1966 Samba Member
Joined: August 18, 2009 Posts: 168 Location: Ohoka New Zealand
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Posted: Thu Nov 22, 2018 2:19 am Post subject: Re: Scat fan shroud with heat |
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Thanks for the replys- a couple more questions re the scat and oem shrouds I have.In the photos below the scat has a diffent style arrangement to the oem in regards to the finning that directs air to the oil cooler.From what I have found when searching the scat has a positive pressure style and the oem has a negetive pressure style.Not sure what this means - can anybody explain and in the last photo a small outlet comes off the oem shroud, what was this used for
Thanks Ross
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FeelthySanchez Samba Member
Joined: February 03, 2011 Posts: 1349 Location: Now is that a real poncho, or a Sears poncho?
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Posted: Thu Nov 22, 2018 9:02 am Post subject: Re: Scat fan shroud with heat |
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Ross,
The small outlet is part of the evaporation control system. It leads to the charcoal canister, which needs pressure to function:
_________________
modok wrote: |
I would like if you had enough clue to communicate what you are doing. |
Ryan Tucker wrote: |
Enough clue..Whats that mean? |
OldIronSpine wrote: |
I'm not sure how compression works.
Turbos don't produce torque, they produce HP. Instead of torque.
The real problem with NA engines is you don't hear the nice whine of the turbo as it spools up.
Before I commit, I'm going to do more research because I don't really know what piston rings are. |
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Kiwi1966 Samba Member
Joined: August 18, 2009 Posts: 168 Location: Ohoka New Zealand
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Posted: Sat Nov 24, 2018 3:24 am Post subject: Re: Scat fan shroud with heat |
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Thanks for that , anybody have any idea re the positive and negetive pressure differences in the two shrouds |
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AlteWagen Troll
Joined: February 23, 2007 Posts: 8497 Location: PNW
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Posted: Sat Nov 24, 2018 9:05 am Post subject: Re: Scat fan shroud with heat |
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Kiwi1966 wrote: |
Thanks for that , anybody have any idea re the positive and negetive pressure differences in the two shrouds |
In 1971 the type II was still running the type I engine and needed additional cooling air directed to the oil cooler thus the 'positive' scoop was created (same as most aftermarket shrouds including scat). The type 181 also used this scoop on some applications as well.
The famous Jake Raby did some testing and found there was a slight increase in head temps on the #1 cylinder as the positive scoop directed cooling air away to the cooler. I believe VW also realized this causing the next evolution which was the peanut port starting in 1975 with FI. In combination with a fan venturi they were able to control the higher operating temps that emission tune would cause.
Not sure of any pressure differences when using positive vs negative, I think pressures are affected more by fan size, and how much factory tin is used. The fan venturi ring smooths out incoming air but not sure its affect on pressure. _________________ Grapes of Wrath $200 Engine Rebuild
Official Dual Carb Thread
Cylinder Head Quick Reference Sheet |
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Kiwi1966 Samba Member
Joined: August 18, 2009 Posts: 168 Location: Ohoka New Zealand
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Posted: Sat Nov 24, 2018 1:14 pm Post subject: Re: Scat fan shroud with heat |
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Thanks Altewagen for your informative reply |
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