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1procrastinator
Samba Member
Joined: September 12, 2007
Posts: 178
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 Posted: Sat Jan 03, 2009 8:42 am Post subject: Venturi ring /fan shroud |
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| Anyone ever use the venturi ring that fits the VW fan shroud on the type 1 engines? The ring is supposed to increase air flow and help the cooling of the engine Who is the supplier? |
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MConstable
Samba Member
Joined: May 04, 2004
Posts: 1822
Location: Saint Charles IL
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neil68
Samba Member
Joined: March 17, 2007
Posts: 3448
Location: Calgary, Canada
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| Posted: Sat Jan 03, 2009 12:40 pm Post subject: Re: Venturi ring /fan shroud |
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| 1procrastinator wrote: |
| Anyone ever use the venturi ring that fits the VW fan shroud on the type 1 engines? The ring is supposed to increase air flow and help the cooling of the engine Who is the supplier? |
I have one on my 2332 cc. It's OEM VW from a '75+ FI Beetle:
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Glenn 
Mr. 010
Joined: December 25, 2001
Posts: 79243
Location: Sneaking up behind you
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| Posted: Sat Jan 03, 2009 12:46 pm Post subject: Re: Venturi ring /fan shroud |
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| neil68 wrote: |
| 1procrastinator wrote: |
| Anyone ever use the venturi ring that fits the VW fan shroud on the type 1 engines? The ring is supposed to increase air flow and help the cooling of the engine Who is the supplier? |
I have one on my 2332 cc. It's OEM VW from a '75+ FI Beetle:
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It helps, but notice the tape and sealing the tin around the cooler... that helps more.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
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Hella-Buggin'
Samba Member
Joined: May 20, 2005
Posts: 538
Location: SF Bay Area, CA
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| Posted: Sat Jan 03, 2009 2:23 pm Post subject: Re: Venturi ring /fan shroud |
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| Glenn wrote: |
| neil68 wrote: |
| 1procrastinator wrote: |
| Anyone ever use the venturi ring that fits the VW fan shroud on the type 1 engines? The ring is supposed to increase air flow and help the cooling of the engine Who is the supplier? |
I have one on my 2332 cc. It's OEM VW from a '75+ FI Beetle:
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It helps, but notice the tape and sealing the tin around the cooler... that helps more. |
What would one use to seal that gap? |
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 79243
Location: Sneaking up behind you
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| Posted: Sat Jan 03, 2009 2:27 pm Post subject: |
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Duct tape or any sealing tape works.
I used foam weather stripping on mine.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
Member #1009
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עַם יִשְׂרָאֵל חַי |
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71sbeetle
Samba Member
Joined: August 15, 2002
Posts: 1334
Location: Las Vegas, NV
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| Posted: Sat Jan 03, 2009 3:06 pm Post subject: |
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| I also used foam weather stripping, it's gray foam that comes in a spool with one side that has adhesive. You can buy various width. I first put it on the shroud itself, put the first piece, then add the foam where the third piece will go, and install the third piece. Works like a charm ! |
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1procrastinator
Samba Member
Joined: September 12, 2007
Posts: 178
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| Posted: Sat Jan 03, 2009 8:29 pm Post subject: Venturi ring/fan shroud |
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| After looking at the above listed supplier for the venturi rings they also have the cylinder tin with the air vane in them (they make the vanes up and add them to the cylinder covers)I looked at some old original cylinder tin and YES the original stuff had the air direction vanes built right in The reproduction pieces DO NOT HAVE THEM Live and learn..I will be getting a set of cylinder tin.. |
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 79243
Location: Sneaking up behind you
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| Posted: Sat Jan 03, 2009 8:35 pm Post subject: |
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No all factory tins have the V deflector.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
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#BlueSquare
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Eric_S
Samba Member
Joined: August 12, 2007
Posts: 862
Location: Sparks (think Reno) NV
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| Posted: Sat Jan 03, 2009 9:09 pm Post subject: |
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VW originally had a piece of foam glued to the full width of the oil cooler and a piece of rubbery (vinyl?) c-channel stuff around the edges of the second and third pieces and around the inside up-n-over piece too where the third piece pokes through. Descriptive enough?
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Eric_S
What are all these extra parts? |
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Eric_S
Samba Member
Joined: August 12, 2007
Posts: 862
Location: Sparks (think Reno) NV
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| Posted: Mon Jan 05, 2009 1:02 am Post subject: |
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It would seem the venturi ring idea is not too new:
http://www.thesamba.com/vw/classifieds/detail.php?id=718793
Looks like an old 356 shroud...and look at the throttle linkage and thermostat!
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Eric_S
What are all these extra parts? |
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rtroy
Samba Member
Joined: June 03, 2009
Posts: 260
Location: California
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| Posted: Sun Aug 22, 2010 2:03 pm Post subject: It's a volute, not Venturi |
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| 1procrastinator wrote: |
| Anyone ever use the venturi ring that fits the VW fan shroud on the type 1 engines? The ring is supposed to increase air flow and help the cooling of the engine Who is the supplier? |
The terminology used regarding this product is incorrect; the item depicted is a volute, not a venturi. Its function is firstly to smooth and secondly accelerate the airflow into the engine's cooling fan. It serves the same basic role as the volute on top of an air cleaner, smoothing the input to the carb.
The first use of a volute for engine cooling fan intake like this, of which I am aware, is on the Porsche 550's four cam "Furhmann engine". Later, Porsche put it on the fan shroud of all their production engines starting sometime in the late '50s when they adopted the "over the top" carburetor linkage - 1957, I think.
Someone has apparently decided to offer them for the VW market.
Note, however, that the unit depicted here is much shorter than the Porsche unit. If you are using a "dog-house" shroud as pictured, that's probably a good thing because the wider fan of the dog-house shroud puts the air inlet opening closer to the firewall, so a shorter ring would be required for that application.
Note that the ring depicted here is deficient in design because the engineer who designed it - or the person in that role - incorrectly (in stock application) assumed that the air is coming straight in from the front. The ring depicted in the pictures stops curving when it becomes parallel with the firewall, however the air is not coming straight in, it is coming radially from the fan center, parallel to the firewall. Thus, the Porsche intake volute, which was designed by an experienced engineer, curls all the way around to accommodate the air coming in radially. The firewall itself is the opposite side of the volute.
Also note that the "stale air thermostat" (primarily on 25 / 36, and early 40 hp engines) served this function as well as that of being a thermostat. Its functionality as a volute is probably better than the volute shown here, and probably not quite as good as the Porsche solution starting circa 1957. The reason that it likely performs better than the volute in the pictures is that a lot of air into the fan is inducted radially between the "throttle ring" and the fan shroud as opposed to the throttle ring and
the firewall.
This means that if you are not running the dog-house cooler, you may want to run the stale air thermostat system - it is quite superior to running without any volute...
Regards,
Richard
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Richard
Karmann Ghia and Porsche 356 enthusiast
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earthquake
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Joined: January 10, 2008
Posts: 3989
Location: SANDY VALLEY, NEVADA
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| Posted: Sun Aug 22, 2010 2:24 pm Post subject: |
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What if you were to mount one of those "Tornado" things they sell to mount in your air cleaner? I have a idea for one, I will try to mock one up and see what you guys think.
Casey
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Steve Arndt
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Joined: August 01, 2005
Posts: 1797
Location: Boise, Idaho
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| Posted: Sun Aug 22, 2010 3:25 pm Post subject: |
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The ring is to make the cooling system quieter and reduce fan noise.
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Das Dragon
Samba Member
Joined: November 13, 2000
Posts: 2474
Location: AZ.
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| Posted: Sun Aug 22, 2010 3:30 pm Post subject: |
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I installed a 'venturi ring' on the dog house shroud in my bus over a year ago. No change in head or oil temps.
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RockCrusher
Samba Member
Joined: August 03, 2010
Posts: 4596
Location: Parkesburg, PA
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| Posted: Sun Aug 22, 2010 3:30 pm Post subject: Re: It's a volute, not Venturi |
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| rtroy wrote: |
| 1procrastinator wrote: |
| Anyone ever use the venturi ring that fits the VW fan shroud on the type 1 engines? The ring is supposed to increase air flow and help the cooling of the engine Who is the supplier? |
The terminology used regarding this product is incorrect; the item depicted is a volute, not a venturi. Its function is firstly to smooth and secondly accelerate the airflow into the engine's cooling fan. It serves the same basic role as the volute on top of an air cleaner, smoothing the input to the carb.
The first use of a volute for engine cooling fan intake like this, of which I am aware, is on the Porsche 550's four cam "Furhmann engine". Later, Porsche put it on the fan shroud of all their production engines starting sometime in the late '50s when they adopted the "over the top" carburetor linkage - 1957, I think.
Someone has apparently decided to offer them for the VW market.
Note, however, that the unit depicted here is much shorter than the Porsche unit. If you are using a "dog-house" shroud as pictured, that's probably a good thing because the wider fan of the dog-house shroud puts the air inlet opening closer to the firewall, so a shorter ring would be required for that application.
Note that the ring depicted here is deficient in design because the engineer who designed it - or the person in that role - incorrectly (in stock application) assumed that the air is coming straight in from the front. The ring depicted in the pictures stops curving when it becomes parallel with the firewall, however the air is not coming straight in, it is coming radially from the fan center, parallel to the firewall. Thus, the Porsche intake volute, which was designed by an experienced engineer, curls all the way around to accommodate the air coming in radially. The firewall itself is the opposite side of the volute.
Also note that the "stale air thermostat" (primarily on 25 / 36, and early 40 hp engines) served this function as well as that of being a thermostat. Its functionality as a volute is probably better than the volute shown here, and probably not quite as good as the Porsche solution starting circa 1957. The reason that it likely performs better than the volute in the pictures is that a lot of air into the fan is inducted radially between the "throttle ring" and the fan shroud as opposed to the throttle ring and
the firewall.
This means that if you are not running the dog-house cooler, you may want to run the stale air thermostat system - it is quite superior to running without any volute...
Regards,
Richard |
I mostly agree with you Richard and I haven't seen the Posche stuff you mentioned BUT the VW engineers did a pretty good job with that Volute and here's why.
What you may or may not know is that every mixed flow fan (every fan blade actually) has, and requires to operate properly, a certain amount of recirculation which shows up as wasted HP and efficiency. The Volute in question COULD have been attached to and sealed to the edge of the shroud opening but isn't. Why is there an edge gap? It reintroduces the loss at the inlet edge back into the incoming air stream at the truncated edge of the volute and increase the overall efficiency of the design. Put a manometer probe at the gap and you will see air flowing out due to the positive pressure in the whole cooling path forcing a greater amount of recirculation. Think of it as cheating the recirc by short circuiting it. The overall effect is increased fresh air than a sealed ring could provide.
RC
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RockCrusher
Samba Member
Joined: August 03, 2010
Posts: 4596
Location: Parkesburg, PA
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| Posted: Sun Aug 22, 2010 3:35 pm Post subject: |
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| Steve Arndt wrote: |
The ring is to make the cooling system quieter and reduce fan noise.
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I wouldn't say that is WHY but it is the benefit of reduced recirculation and turbulence at the input which means higher efficiency.
RC
_________________
[email protected] Please use email for all general inquiries.
I will be happy to speak to anyone who has a serious inquiry (meaning real potential business for RC enterprises) or a parts order. Due to machining noise causing missed calls all calls will be returned promptly. |
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rtroy
Samba Member
Joined: June 03, 2009
Posts: 260
Location: California
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| Posted: Sun Aug 22, 2010 3:48 pm Post subject: Re: It's a volute, not Venturi |
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| RockCrusher wrote: |
I mostly agree with you Richard and I haven't seen the Posche stuff you mentioned BUT the VW engineers did a pretty good job with that Volute and here's why.
What you may or may not know is that every mixed flow fan (every fan blade actually) has, and requires to operate properly, a certain amount of recirculation which shows up as wasted HP and efficiency. The Volute in question COULD have been attached to and sealed to the edge of the shroud opening but isn't. Why is there an edge gap? It reintroduces the loss at the inlet edge back into the incoming air stream at the truncated edge of the volute and increase the overall efficiency of the design. Put a manometer probe at the gap and you will see air flowing out due to the positive pressure in the whole cooling path forcing a greater amount of recirculation. Think of it as cheating the recirc by short circuiting it. The overall effect is increased fresh air than a sealed ring could provide.
RC |
Fair enough, I've never seen that setup, either in original VW or from the current after-market vendor. Porsche attached their volute directly to the shroud. However, their fan wasn't so wide, and there wasn't all that other stuff in the area, like the dog-house, etc. So, they are not quite apples to apples for comparison sake and thus I suppose I can relax my criticism of the designer's work. It may also be that the proximity of the volute to the firewall affects the design more than might at first meet the eye, what with surface turbulence and drag introduced there.
Either way, I'd rather have a volute than not, of either design.
RT
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Richard
Karmann Ghia and Porsche 356 enthusiast
Founder, The Karmann Ghia Club of N. America |
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rtroy
Samba Member
Joined: June 03, 2009
Posts: 260
Location: California
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| Posted: Sun Aug 22, 2010 3:49 pm Post subject: |
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| RockCrusher wrote: |
| Steve Arndt wrote: |
The ring is to make the cooling system quieter and reduce fan noise.
:) |
I wouldn't say that is WHY but it is the benefit of reduced recirculation and turbulence at the input which means higher efficiency.
RC |
RC, I think you mean to say it's an effect, but not the primary purpose the engineers were seeking. In that, we agree.
RT
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Richard
Karmann Ghia and Porsche 356 enthusiast
Founder, The Karmann Ghia Club of N. America |
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rtroy
Samba Member
Joined: June 03, 2009
Posts: 260
Location: California
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| Posted: Sun Aug 22, 2010 4:26 pm Post subject: Re: It's a volute, not Venturi |
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| RockCrusher wrote: |
I mostly agree with you Richard and I haven't seen the Posche stuff you mentioned BUT the VW engineers did a pretty good job with that Volute and here's why.
...snip...
RC |
For your viewing pleasure, here you can see the Porsche volute rather well:
http://ghiacoachworks.com/share/lsr_cooling_system.html
The "top" of the chain of related web pages is here:
http://ghiacoachworks.com/share/denzel_lsr.html
Enjoy!
RT
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Richard
Karmann Ghia and Porsche 356 enthusiast
Founder, The Karmann Ghia Club of N. America |
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