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BugMan114 Samba Member
Joined: March 22, 2007 Posts: 3744 Location: Ellenwood, GA
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Posted: Mon Sep 05, 2011 9:14 pm Post subject: |
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well now this thread did kinda go in the wrong direction a few times, but it did reveal that these smogpumps are infact being used as superchargers, on single cylinder motorcycles. so calling it a supercharger isn't exactly incorrect, depending on the usage. but obviously on a VW motor, it wouldn't work as a supercharger. _________________ 1974 Super Beetle: Custom resto in progress
1972 Super Beetle: Daily Driver
1971 Std. Beetle w/ 1929 Mercedes Benz Gazelle kit
1960 Baja Bug
1969 Baja Bug
Sand Rail- Homemade
Sand Rail- FUBAR
Aircooled Airheads
Why the hell do they call it a gland nut. its obviously a big fat bolt!!! |
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John Moxon Samba Moderator
Joined: March 07, 2004 Posts: 13943 Location: Southampton U.K.
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Posted: Tue Sep 06, 2011 12:21 am Post subject: |
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BugMan114 wrote: |
well now this thread did kinda go in the wrong direction a few times, but it did reveal that these smogpumps are infact being used as superchargers, on single cylinder motorcycles. so calling it a supercharger isn't exactly incorrect, depending on the usage. but obviously on a VW motor, it wouldn't work as a supercharger. |
Yes that's true but given that this is a VW website it would have been wrong to depict this item as anything but a VW Smog Pump. It would be an entirely different matter it this were a website for small motorcycles...but it's not.
I think we've just about exhausted the subject. Thanks to all who have contributed...it's been fun.
If anyone feels there is more to add (VW related) PM me and I consider unlocking. _________________ John.
Judson Supercharger Information on The Samba
My 1958 Shorrock Supercharged Karmann Ghia
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John Moxon Samba Moderator
Joined: March 07, 2004 Posts: 13943 Location: Southampton U.K.
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Posted: Thu Feb 27, 2014 4:43 am Post subject: VW/Porsche 912 Smog Pump |
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COMPARISON of VW and PORSCHE 912 SMOG PUMPS
A friend of mine recently sold one of these VW Smog Pumps via eBay-UK - I was amazed how much he got for it despite describing it as "Smog Pump", not "Rare VW Supercharger" - you can take a look at item # 261378538490 if its still available. Whilst doing his research - he discovered that there ARE differences between the VW marked Smog Pumps and those used on the Porsche 912 - but he has an interesting theory about their interchangeability. I am recording his findings here in the hope that it may be some help to anyone trying to keep an old 912 in totally original spec.
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This Topic - and photos found elsewhere - do establish that this type of Midland Ross pump was used on Porsche 912 models destined for emission controlled states in USA - probably just for 1968 & 1969. But research has revealed that there were some VERY minor difference between the VW and the Porsche versions.
The most visually striking difference is that the VW version has 2 nice VW roundels stamped into alloy inserts pressed into the pump body - whilst the Porsche version just has a capital "P" stamped into the alloy inserts.
There are also functional differences.
The inlet and outlet ports of this product have different sizes, and are oriented at different angles. If you look at the pump in a 912 - then the mounting bracket would be on the right, and the smaller port is on the top. If you hold a VW pump with the bracket on the right - the larger port will be on the top.
<<...>> <<...>>
I would have assumed that the Inlet port would be larger & Outlet would be smaller - because compressed air has less volume - BUT - on looking at the 912 set-up the top (smaller) port is connected to the air-filter - so it must be collecting "clean air" as its Input. I suppose what really sets which is Input and Output is which way the pulley turns. So if my assumptions about how this pump works - and which way a 912 engine turns - are correct, then a 912 pump sends air downwards [and so would a VW pump mounted/belted the same way]. As far as comparing a VW pump to a Porsche pump is concerned - all that matters is the size/orientation of the ports - and they ARE different [but can almost certainly be converted to be the same]
I have NOT ever taken one of these pumps apart - but I firmly believe that if you undo the 4 bolts that hold the cover - you could lift it off, and turn it through 180 degrees and put it back on, and you would have converted a VW pump to the Porsche layout. I have included a picture to show that there is probably nothing inside to stop such a conversion.
<<...>>
Finally - it looks to me that the VW version has a slightly larger pulley wheel than the Porsche version. If I am right - and you want to use a VW pump on a 912 - you might swap on your old 912 pulley - or you might just accept it running a shade slower (needing you to adjust the belt tension, or use a marginally longer belt).
So if you own a 912 - and want to keep it 100% stock - or need to get it through some sort of Smog Test/Inspection in states such as California or Delaware - then if you agree with my logic, you may be able to buy and convert a VW pump to 912 layout. If you have tried this - let us know if it works.
In all of the information available on the internet - I have never found reliable information on what VW model the VW marked pumps actually got used on. Maybe VW's plans changed - and they never did get used - which could be why companies like Proops of London (See http://www.proopsbrothers.com/history.html ) were selling them off as possible superchargers for small capacity engines. |
Porsche 912 application.
If you KNOW what VW they were used on - let us know. _________________ John.
Judson Supercharger Information on The Samba
My 1958 Shorrock Supercharged Karmann Ghia
Stop dead photo links! Post your photos to The Samba Gallery! |
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fcampbell356 Samba Member
Joined: December 15, 2007 Posts: 217 Location: Pensacola, Florida
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Posted: Fri Feb 28, 2014 1:30 pm Post subject: Smog Pump |
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Smog pumps were used on the VW Type 2 Bus around 1973-1974 also
on the VW Type IV around the same time. Most were taken off unless
in a regulated state that required them. This as I remember.
Frank |
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vdubbles24 Samba Member
Joined: February 08, 2009 Posts: 335 Location: Grandview, Indiana
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