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volksaddict
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Joined: August 19, 2003
Posts: 1724
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 Posted: Fri Jan 15, 2010 7:22 am Post subject: Those big air boxes, 74? |
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| I guess the big air intake boxes are a "factory improvement" from 73 to 74. What's under them? Can you take them off and fill the holes and have it look like a 73? Anyone found a diference in cooling with them or a problem with the sleeker 73 vents? |
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sam_w
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Location: Petaluma, CA
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| Posted: Fri Jan 15, 2010 8:03 am Post subject: |
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Someone did a controlled test, and found that the 'air boxes' on a 74 drop the oil temps by about 5 degrees F.
Don't remember the site but think it was something to do with the Rockies.
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J Flare
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Joined: September 27, 2004
Posts: 309
Location: San Diego
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| Posted: Fri Jan 15, 2010 8:41 am Post subject: |
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| I have heard that they help with the circulation of the air for the heater boxes as well. |
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Ian Epperson
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| Posted: Fri Jan 15, 2010 1:21 pm Post subject: |
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I have heard that they help prevent the exhaust fumes from entering the fresh-air heat system (on a 74, but not a 73).
I have heard that they help with airflow at freeway speeds.
I have heard that they help prevent the car from overheating while idling in traffic.
I have seen pictures of conversions from the 74 style "muffs" to the 73 style.
I have seen pictures of conversions from the 73 style to the 74 style "muffs."
I have seen people mod the front of the "muffs" to try and scoop air into the engine compartment.
Maybe we can start a few more ideas as to their purpose. I think they were to prevent people from being stuck on the side of the car due to the extreme suction! 
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SilverThing 
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Joined: July 19, 2004
Posts: 810
Location: Everett
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| Posted: Fri Jan 15, 2010 6:33 pm Post subject: |
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German speakers sometimes (maybe even often) refer to them as Hamsterbacken "hamster cheeks"
not to be confused with hamster baking...
perhaps they're supposed to be used to carry food like hamsters do?
A few German forum posters on another forum seem to think that they reduce the amount of dust sucked into the engine compartment from dirt being flung by the rear tires (at least that is how I understood what was said).
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yellow73kubel
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Joined: August 17, 2008
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Location: Columbia, SC
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| Posted: Fri Jan 15, 2010 7:22 pm Post subject: |
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I'm going with the hamster cheeks thing, that sounds good..
At freeway speeds, I can see an extra amount of air forced in with the '74 muffs. At idle, the larger vent area of the '73 design seems like it would be much better. Possibly a little better for keeping water from being splashed in ('74)? |
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volksaddict
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| Posted: Fri Jan 15, 2010 8:04 pm Post subject: |
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| So, what's underneath them? Big holes, or 73 style vents? |
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esauber
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Joined: November 16, 2008
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Location: NW Ohio
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| Posted: Fri Jan 15, 2010 8:20 pm Post subject: |
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Big holes the same size as where the vents are.
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esauber
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| Posted: Fri Jan 15, 2010 9:12 pm Post subject: |
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Big holes the same size as where the vents are.
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mgirdner
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Joined: January 21, 2003
Posts: 199
Location: Covina, CA
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| Posted: Sat Jan 16, 2010 12:02 pm Post subject: Re: Those big air boxes, 74? |
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| volksaddict wrote: |
| ... the big air intake boxes are a "factory improvement" from 73 to 74..... Anyone found a diference in cooling with them or a problem with the sleeker 73 vents? |
Tim Caves, local Thing expert and owner of TC's Old Volks Home in Tujunga, CA, told me the "ear muffs" on the '74 Thing were designed to eliminate the "Bernoulli Principle" afflicting '73 and earlier Type 181s.
Recall from your high school physics that the Bernoulli Principle is what causes lift on wings and is what keeps most airplanes aloft.
The Type 181 wasn't designed to be driven on the Autobahn. The problem wasn't discovered until they were sold in the US and we took them on our freeways.
Because of the taper of the back end of Things, at higher speeds, it would create negative air pressure at the air intakes and cause the engine to have to work harder to overcome the vacuum and suck in air.
Thusly:
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Captain Spalding
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Joined: February 19, 2005
Posts: 2519
Location: . . . in denial.
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| Posted: Sat Jan 16, 2010 12:35 pm Post subject: Re: Those big air boxes, 74? |
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| mgirdner wrote: |
. . . the "ear muffs" on the '74 Thing were designed to eliminate the "Bernoulli Principle" afflicting '73 and earlier Type 181s.
Recall from your high school physics that the Bernoulli Principle is what causes lift on wings and is what keeps most airplanes aloft.
The Type 181 wasn't designed to be driven on the Autobahn. The problem wasn't discovered until they were sold in the US and we took them on our freeways.
Because of the taper of the back end of Things, at higher speeds, it would create negative air pressure at the air intakes and cause the engine to have to work harder to overcome the vacuum and suck in air. |
I'm not disagreeing with the analysis in the drawing, but it fails to illustrate how the earmuffs solve the suction problem. Having the air intake openings on top of the earmuffs is hardly a solution to a low pressure problem. Air passing at speed over those openings would also tend to suck air out of the engine compartment via the venturi effect, no?
"The problem wasn't discovered until they were sold in the US and we took them on our freeways." You're killin' me.
BTW SilverThing, love the hamster cheek reference! |
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Doc*181
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Posts: 479
Location: Belgium
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| Posted: Sat Jan 16, 2010 12:50 pm Post subject: Re: Those big air boxes, 74? |
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| Captain Spalding wrote: |
"The problem wasn't discovered until they were sold in the US and we took them on our freeways." You're killin' me.
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Maybe the German Autobahn was closed for a decade at that time?
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SilverThing
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Joined: July 19, 2004
Posts: 810
Location: Everett
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| Posted: Sat Jan 16, 2010 2:28 pm Post subject: Re: Those big air boxes, 74? |
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| Captain Spalding wrote: |
| BTW SilverThing, love the hamster cheek reference! |
Thanks!
I remember when I was first looking at buying a Thing that some people were calling them wader boxes. I never really understood the term as there are plenty of other places for water to get into the engine compartment.
Some folks have put forth that the boxes were a general improvement to the model having nothing to do with the heating system, but I am a little skeptical because why were they only applied to vehicles with fresh air heating? If it were a general improvement wouldn't it have been applied to all vehicles? There are plenty of examples of post 74 181 that do not have them.
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Doc*181
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| Posted: Sat Jan 16, 2010 3:04 pm Post subject: Re: Those big air boxes, 74? |
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| SilverThing wrote: |
Some folks have put forth that the boxes were a general improvement to the model having nothing to do with the heating system, but I am a little skeptical because why were they only applied to vehicles with fresh air heating? If it were a general improvement wouldn't it have been applied to all vehicles? There are plenty of examples of post 74 181 that do not have them. |
Indeed!
It is a fact that there was not one German Bundeswehr 181 with those air intake boxes. Those cars came standard with a BN4 heater.
My civilian car doesn't have a BN4 heater, but does have those air intake boxes. It must be something with different airflows between those two types of heating?
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SilverThing
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| Posted: Sat Jan 16, 2010 5:23 pm Post subject: Re: Those big air boxes, 74? |
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| Doc*181 wrote: |
It is a fact that there was not one German Bundeswehr 181 with those air intake boxes. Those cars came standard with a BN4 heater.
My civilian car doesn't have a BN4 heater, but does have those air intake boxes. It must be something with different airflows between those two types of heating? |
I've noticed a few Euro vendors divide exhaust systems into two categories: Military (Bundeswehr) and Civil. A bit much of a differentiation if you ask me since there are examples of both exhaust systems being used on either side of the divide (73 Thing and Danish Military come to mind). But I digress...
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volksaddict
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| Posted: Sat Jan 16, 2010 8:01 pm Post subject: |
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| Oh! So post 73's came both with and without the big dorky boxes? So it's not just a year change. You'd think if it was a cooling improvement they would have put them on all of 'em from then on. Interesting that they would make them both ways. |
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kubelmann
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| Posted: Sat Jan 16, 2010 8:30 pm Post subject: |
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Super NO!!!! For all U S Imports:
73: Louvers
BN-4 Gas Heater
No standard air cooled VW heat exchanger heating system
74: Muffs
No gas heater
Unique one-of-a-kind interior heat distribution systems
Standard VW air cooled heat exchanger heating system.
Type 181 production worldwide 1968 - 1980
1968 - 1972 swing axle
1973 -1974 US Import ball joint front IRS rear gas heat 73 exchange heat 74
1875 - 1980 Incredible variation as to configuration.
1974 Acapulco (with Muffs) produced in Blue/White and Orange/White
If you have a showroom Orange and White "Las Brisas Special" with the accessories, head to BK and Auction HO |
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Captain Spalding
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Location: . . . in denial.
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| Posted: Sat Jan 16, 2010 10:16 pm Post subject: |
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| volksaddict wrote: |
| Oh! So post 73's came both with and without the big dorky boxes? So it's not just a year change. You'd think if it was a cooling improvement they would have put them on all of 'em from then on. Interesting that they would make them both ways. |
I think the observation made was that from 1974 onwards cars with Eberspächer heaters didn't have the hamster cheeks and cars with the heat exchangers did. What seems to be the prevailing notion is as follows: cars with heat exchangers draw air through the engine compartment. The air comes through the vents on the side of the compartment, past the fan, through the fan shroud, through the flexible hoses to the heat exchangers, and then into the passenger compartment. The thinking is that because of the proximity of the side vents to the exhaust, too much exhaust was being drawn in to the engine compartment and subsequently pumped through the heat exchangers into the passenger compartment. Ostensibly the muffs are meant to mitigate the exhaust fumes.
I don't know how effective the muffs actually are at controlling exhaust fumes, but that is the only explanation for the muffs that doesn't seem blatantly in error on its face. That said, I've yet to hear of any piece of documentation or literature that explains what the earmuffs are for. I can imagine that if I were Joe VW engineer and I were adding earmuffs to a car because drivers were complaining about the headaches they were getting from carbon monoxide in the passenger compartment, I might be a little shy about mentioning it in the literature. But in the absence of that literature, all we are left to is speculation. |
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volksaddict
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| Posted: Sun Jan 17, 2010 7:22 am Post subject: |
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| An answer that makes sense! |
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mondshine
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| Posted: Sun Jan 24, 2010 9:18 pm Post subject: |
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They are installed on '74's to prevent dust which is sucked into the engine compartment from being blown through the heat exchangers and into the car's interior.
After fighting high cylinder head temps at constant speeds above 65 MPH, I modified one of these boxes to duct cold air right into the fan inlet.
I realize this modification is not for everybody, but I can now drive 75 MPH for hours and never exceed 350* CHT.
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