TheSamba.com :: View topic

Fri May 26, 2006 1:55 pm

I've read several people's postings that have said that they have used a Porsche 356 generator pulley to help cool their bus. Will the Porsche pulley fit an alternator or just a generator? Will I need a new size belt or will the stock VW belt work?

Fri May 26, 2006 2:20 pm

it will fit an alt or gen... both accept the same pulleys.
You will need a smaller belt. I don't know the size. I once used a small pulley from a small generator (it's smaller) to get more cooling, and had to use a smaller belt... forget the size. I might have had to do some shimming. I took that off cause my engine ran too cool and put it somewhere safe from me finding it.. :wink:

Fri May 26, 2006 2:24 pm

hey guys belt size is 15345 I have been running one for a while now and it dropped the oil temps 20 degrees later Mark dearing

Fri May 26, 2006 2:31 pm

The whole point of using the smaller pully is so that you CAN use a smaller belt.

On a V-Belt system, with non-movable pulleys (like the vw engine) the length of the belt is what determines the effective diameter of the pulley. Which is what determines your Fan Speed to Crank Pulley Speed Ratio. You can get a slightly faster fan speed on your stock pulley just by shimming it up and using a smaller belt. Every pulley will have a range of effective diameters that it will be able to adjust to. It's all about increasing the ratio. My engine came with a stock gen pulley, and a 912mm belt. gave me about a 1.73:1 fan ratio. I put on a 36hp pulley, with about 12 shims, and that allowed me to use a 890mm belt. Now my fan speed ratio is almost 2:1. You can go even smaller with the porsche pulley.

Start out by marking your pulleys and counting the rotations to see what your ratio is at right now - then decide where you want to go from there. You'll have to just do trial and error by swapping out belts and pulleys, because computing effective diameters in V-Belt systems requires math beyond the scope of the project.... I just bought a range of belt sizes, and tried to see what would fit.

Fri May 26, 2006 3:12 pm

Your final ratio will also depend on what crank pulley you are using. I use a Porsche top and a stock 7" crank pulley which gives me a 2.2 to 1 ratio. Most all aluminum crank pulleys are 6 3/4".

The belt that i use is a: ContiTech AVX 10x888.

Fri May 26, 2006 5:46 pm

I agree with VWBrain, 15345. Really that means the belt is 34.5"

I like the Dayco brand belts that are available at Advance auto parts. (the ones at Autozone suck!)

The 356 parts are all available new which is great as well. I never realized that a pulley hub could fit a Gen/Alt so well! The VW pulleys just seem sloppy by comparison.

A good upgrade, but a little pricey at the same time.

Fri May 26, 2006 6:48 pm

If you run the 356 pulley, for mechanical overkill you might want to buy a welded and balanced fan set-up with the increased speed it will be running.

Reduces the risk of the stock fan falling apart at speed.....

Sat May 27, 2006 5:01 pm

i thought the 356 had the same fan as a type 1 motor, non-doghouse style. shouldnt matter as long as your not running some aftermarket crap. the porsche motor, im guessing, would have a higher redline anyway

Sat May 27, 2006 7:26 pm

i dont think anyone really runs on the street a motor with the horspower that it would take to make a fan come apart.
use a 40hp fan on the 36 hp due to fan has more blades on it,wich will cool alot better.

Mon May 29, 2006 6:06 pm

On a normal engine I think the fan will frag at about 6000-6500 RPM. I am swag/calcing for a 356 setup about 5500 RPM max.

Mon May 29, 2006 6:37 pm

I believe your guess-timate on the fan fragging at 6000-6500 is not correct.

My pulley ratio is 2.1 to 1 so at 3300 RPM cruising hour after hour on the highway the fan is at 6930 RPM. Stock dog house fan non-rebalanced or welded.

With a stock ratio of 1.75 to 1 at 3300 RPM the fan is at 5775 RPM.

These are my real numbers from my two buses.

HTH

Mon May 29, 2006 7:06 pm

Ok I've got some questions to add to this post, not trying to hijack it just need related info. Which of the following model pulleys or are all correct for adaptation to VW use 356A, 356B, 356C, and 912? Also other than swaps, samba, and eBay. What is the best place to source the parts needed for a reasonable price? Thanks for any info,

Mon May 29, 2006 7:18 pm

i just bought one from stoddard in ohio i think it was around 45.00 but i bought other things but that price is real close.they are listing it for all models.

Mon May 29, 2006 9:57 pm

Das Dragon wrote: I believe your guess-timate on the fan fragging at 6000-6500 is not correct.
HTH

I thought he meant it would frag at 6500 engine RPM's, that would have the fan spinning north of 13000!
I just put a 13345 belt on my 1600 dp and, with the stock alternator pulley and aluminum crank pulley I get a 2.1:1 ratio.
I had to add a bunch of shims to get it to work (I think I have 14 in there), but I got it worked out.
I never rev my engine over 4K RPM anyhow, so the fan should be safe.
I have never heard of a stock VW fan grenading, only aftermarket crap.

Tue May 30, 2006 2:24 pm

Oops, yes I meant to specify engine RPM.

http://www.aircooled.net/new-bin/viewproductdetail.php?keyword2=ESM0001&cartid=

According to John it is 6000RPM with a stock belt.

Since my engine at most hits 5K with a 356 pulley I am not that concerned either ;)

For the conversion at MINIMUM you need:
1. Inner pulley half
2. Outer pulley half
3. Hub

What I suggest:
1. see above 1-3
2. 10 new shims (yes the Porsche ones are better)
3. New key to hold hub

Nice to have:
1. New 36mm pulley nut :) Just looks old school, but the VW nut works fine as well.

I got mine through Klasse356.com and was pleased by the good service.

https://secure.klasse356.com/catalog/ShowItems.asp?Category=EEL

Tue May 30, 2006 2:28 pm

As you can see ,i drive with an original Porsche belt size 9,5 *888.

I ordered mine at a Porsche dealer ship and the belt was in combo with the pulley.

Tue May 30, 2006 2:51 pm

Quote: Oops, yes I meant to specify engine RPM.

Sorry Pillow...I was thinking fan RPM when i read your post, my mistake! :oops: #-o

Tue Jul 01, 2008 6:58 pm

does anyone know the part #'s for these?

Wed Jul 09, 2008 3:37 am

Aside from 356Klasse also try stoddard.com - they seem to have numbers and parts and similar prices. I think Berg used to make them but has dropped them. Try the e auction site but make sure you get the smaller diameter. Also there is some differences in the 36mm nuts to watch for - 25hp VW look similar. I've only mocked mine up but I either had to use a solid 1mm fan spacer washer or turn the inside down on the 36mm nut slightly to fit. I turned my nut in the end.

The belt is a little curious too - stoddard lists it as a 13x850, 356 lists it as 13x825 but volkswouter says 9.5x888. Given VW stock belts are listed 10x900 (6V), or 9.5x1110 (gen/alt) or 11.3x912 (late alt) I'd say the 13mm is a little wide for our lower pulleys. So which belt?

Wed Jul 09, 2008 6:17 am

I have been using the same 9.5x888 belt for 7 years now.