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Sun Sep 12, 2010 8:52 am

Is any one ever try Reducing Alternator Pulley size to have more air cooling?

I had found a good articles that I would like to share.
http://www.offroadvw.net/tech/

Sun Sep 12, 2010 12:10 pm

I don't recall anyone manufacturing a smaller alternator or generator pulley.

But I have seen a larger crankshaft pulley on Aircooled.net.

Similar theory.

Sun Sep 12, 2010 12:47 pm

There have been instances where the fan blew apart from centrifugal force. I'd really think twice before spinning that sucker faster than it was designed to go!!

Dave

Sun Sep 12, 2010 12:49 pm

stoneloco808 wrote: I don't recall anyone manufacturing a smaller alternator or generator pulley.

But I have seen a larger crankshaft pulley on Aircooled.net.

Similar theory.

Unfortunately I can't use it because of the Full flow

Sun Sep 12, 2010 2:17 pm

First make sure you are getting enough air to the engine compartment.

Second make sure you are using a welded fan if you intend to spin it faster.

Your options are either a larger crankshaft pulley or smaller alternator pulley. Most aftermarket pulleys are 6 3/4" while the stock ones are 7" then they have some large aftermaket ones that are even larger in diameter. If those extra large ones do not fit then make sure you at least get a stock 7" pulley and even some aftermarket companies like Empi and CB have stock size 7" pullies.

For the alternator pulley you have to get a Porsche 356 pulley. It is three pieces with a hub, and outter and inner half. You can usually find them on ebay or Pelican Parts...

http://www.pelicanparts.com/cgi-bin/ksearch/pel_se...ER_TOOL=ON

Sun Sep 12, 2010 2:25 pm

356 upper pulley will work to get the fan speed back to normal if you have to use a power pulley, or you can just use the 356 upper pulley with the stock lower pulley but you better have a welded fan and keep the rpms low or it will frag

Sun Sep 12, 2010 2:25 pm

A smaller Porsche gen/alt pulley speeds up the air flow. My bus is a highway cruiser and rarely rev to 5K. I use a welded/balanced fan and have had no problems for eight years now. The increase in air flow is noticeable.
Do a search here on the samba for Porsche pulley. Also in your pic you have an aluminum crank pulley which is 6 3/4" in diameter. A stock later T-1 'D' pulley is 7" in diameter and will speed up the fan also.

Mon Sep 13, 2010 3:29 am

Das Dragon wrote: A smaller Porsche gen/alt pulley speeds up the air flow. My bus is a highway cruiser and rarely rev to 5K. I use a welded/balanced fan and have had no problems for eight years now. The increase in air flow is noticeable.
Do a search here on the samba for Porsche pulley. Also in your pic you have an aluminum crank pulley which is 6 3/4" in diameter. A stock later T-1 'D' pulley is 7" in diameter and will speed up the fan also.

Thank you for sharing your own experience, I think that I'll buy smaller Porsche gen/alt pulley and welded/balanced fan.

Do you know the size difference between the T1 alternator pulley and smaller Porsche gen/alt pulley?

What kind of belt you use to fit with Porsche gen/alt pulley and STD T1 D Pulley
How much is the smaller Porsche gen/alt pulley and from where I can get one?

Mon Sep 13, 2010 8:38 pm

I run a Porsche generator pulley on my alternator, but I also run a Saco power pulley. I estimate the fan spins pretty close to stock speed with this combo. If I want to spin the fan slower in the winter or for more horsepower, I can just switch to a stock VW generator pulley. Very simple.

Tue Sep 14, 2010 2:45 am

thefladge wrote: I run a Porsche generator pulley on my alternator, but I also run a Saco power pulley. I estimate the fan spins pretty close to stock speed with this combo. If I want to spin the fan slower in the winter or for more horsepower, I can just switch to a stock VW generator pulley. Very simple.

Thanks for posting your Porsche Pulley photo. What it's size to do some math?, also what is the belt size with using T1-D Pulley.

Tue Sep 14, 2010 7:42 am

pharos, the stock pulley is app. 4 1/4" and the Porsche is 3 3/4". The belt I use is a Conti 10X888. A bought my pulley from Bernie Bergmann about 9 yrs ago. I don't know if he still sells them.
Hope that helps.
FYI, the ratio between my alt & crank pulley is 2.2 to 1.

Thu Sep 16, 2010 8:56 am

Hmmm this sounds like it would be a great option for those with freeway flier transmissions to get the fan speed back up closer to stock.
Does anyone know what the fan speed is in a car with a freeway flier at say 65mph?

Thu Sep 16, 2010 9:23 am

For the people who want to run a Serpantine belt system; BMD Pulleys sells two sizes of top pullley and several sizes of bottom pulley for various oil pumps. These rations can be used to get fan Over-Speed if that is what is needed. I bought the Tiny Dry sump bottom pulley and smaller top pulley but have not installed yet.

Wed Sep 29, 2010 10:35 am

Pulley And Belt Calculator
http://www.csgnetwork.com/pulleybeltcalc.html