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Technical => Engine Tech Forum => Topic started by: spindle3 on May 13, 2014, 06:39:08 PM

Title: Serpentine belt
Post by: spindle3 on May 13, 2014, 06:39:08 PM
 Hello all; I'm thinking about getting a serpentine belt system for my 1641 beetle.  Anyone recommend either Scat, Bugpack or Empi ?
Title: Re: Serpentine belt
Post by: mitchy965 on May 13, 2014, 09:03:32 PM
don't recommend any manufacture and still don't see the need for this product (unless its a bling contest) sorry.
Title: Re: Serpentine belt
Post by: Hansk on May 14, 2014, 02:12:09 AM
don't recommend any manufacture and still don't see the need for this product (unless its a bling contest) sorry.


Agreed  , save your money(and your fan) , stay away from these things.
Title: Re: Serpentine belt
Post by: spindle3 on May 15, 2014, 08:39:31 AM
 Ok, thx.
Title: Re: Serpentine belt
Post by: owdlvr on May 15, 2014, 01:20:31 PM
don't recommend any manufacture and still don't see the need for this product (unless its a bling contest) sorry.


Agreed  , save your money(and your fan) , stay away from these things.

Assuming one installs a quality welded fan at the same time, they aren't a problem. With a quality welded fan they offer less belt wear and easier tension adjustments. Had my serpentine setup on an engine that regularly went to 7500rpm with no problems. Well, okay no problems related to the belt setup. I ran one on the high-revving engine because I didn't want the fan drive slipping. I'd be running now on my dry-sumped engine, to correct the fan ratio, if I could get one.
Title: Re: Serpentine belt
Post by: josh on May 15, 2014, 07:46:05 PM
But how many times will even a welded fan take it? Belt slip is a good thing! a stock sized crank/alt pulley ratio is what? 2.5:1?? Just a wild guess.... so at 7500rpm the fan is turning almost 19,000 RPM if a serp belt indeed doesnt slip :c029: :c029: :c029: I doubt the fan is efficient at ludacris speed? I bet it is cavitating like a mofo!

I just read a post the other day where a guy some how sets his up to slip like a stocker....not sure how?
Title: Re: Serpentine belt
Post by: BUSDADDY on May 15, 2014, 08:12:33 PM
Indeed, why reinvent a system when an office tower full of white lab coated pocket protector wearing meticulous German engineers already figured it out 50 years ago? Not only is it super simple, it incorporates built in safety reliefs that you likely didn't even notice. How much time do you really spend at those revs that it won't cool off 2-3 seconds later when you let off and the fan catches up when the OG belt grips again? Seems to me the only thing a serpentine system is good for (aside from bling) is if you are driving a supercharger and A/C pump plus bonus alternators over and above the regular accessories. Why make things complicated?, not everything you read in a flashy magazine is really what you need ;)
Title: Re: Serpentine belt
Post by: owdlvr on May 15, 2014, 08:35:49 PM
Well if everyone ran under the theory that the German engineers did it best, we'd all still be driving bone stock splits with 36hp. I, on the other hand, am quite happy with the suspension, engine, interior, safety and other improvements I've made over the engineers in '71.

But to each his own.

I do agree, however, that at high RPM's the stock fan has to be cavitating like made, fortunately I was only spiking the RPMS to those levels (most of the time). But regular driving on the old high-revving motor meant cruising at 5500-6500 rpm, which means a stock fan belt setup is slipping so much you cook belts in short order. Who knows what kind of airflow the heads were getting?!

-Dave
Title: Re: Serpentine belt
Post by: mitchy965 on May 15, 2014, 08:58:27 PM
well i have spun my engines up there as well and usually replace my belt cause it old and rotten not cause its been cooked,i like the fact that it slips(a little) for the same reason josh stated. it really comes down to what you want to spend your $s on. i never thought it was hard to tension a type 1 fan belt and have no belt flinging issues so i spent my cash elsewhere. 2 each their own  :victory:  and Dave.... your car is outstanding.
Title: Re: Serpentine belt
Post by: Hansk on May 18, 2014, 01:47:18 AM
http://www.offroadvw.net/tech/wes/fan.html

A very interesting article about our cooling fans disproving myths such as cavitation.
Also showing that increasing fan speed does not equally increase cooling and that the power
required to turn a fan faster multiplies incredibly .   The last sentence at the bottom says it all.
Title: Re: Serpentine belt
Post by: mitchy965 on May 18, 2014, 12:35:21 PM
what an excellent link Hansk!!! sorta what i thought, its a simple, self regulating system that once properly installed rarely gives trouble or costs much even when taken (way) beyond its original design intents. there are weaker links to attend to....
Title: Re: Serpentine belt
Post by: Hansk on May 20, 2014, 07:54:29 AM
Ya , when I first read this a few years ago I realized that I would be wasting my time trying to make more power at higher RPM's in my type 3.  With the fan bolted directly to the crank , there is no belt slip and no temporarily disconnecting it , just multiplying power loss as the rpm's increase .