3.6 ers out there-anyone done the single pulley conversion?

[JonT]

Was it worth it? would you recommend it? what were the effects of the conversion positive/negative? Thanks

[pbs911]

Are you refering to the alt/fan, or the crank?
I used the impeller hub to go with a single pulley at the fan/alt. This does not change the fan speed but slows down the alt. Since my SC has very little in the way electrical run gadjets I have no problems. Really cleans up the engine compartment, eliminates the need for the fan belt sensor and makes changing the belt much easier. The same impeller hub can be used for the 964 and 994 3.6. I wnt with the genuin Porsche part.

I did not change the crank pully. On the 964 the three pulley at the crank is also used as a harmonic balancer, which was eliminated on the 993 with mods to the crank, rods and pistons. Some say there is no problem moving to a single pulley. Bill V posted a nice pic of a 964 crank that broke in half using the single pulley conversion. I would think that Porsche would have used the single pully if possible. But then again the RS did come with a single pulley. For me it is not worth the risk as little improvement is likely at a much greater possible expense.

[rattlsnak]

I changed the crank pulley and used a single pulley device for the top. Things have changed over the last couple of years, but when I did it, the factory part was for a serpentine belt, and you had to use some kind of tensioner pulley to tighten it (like air conditioning). I wanted to use a regular V belt so I went with a stock SC lower pulley, and made an aluminum pulley for the top. Basically it was a 3" inch piece of stock aluminum I picked up at a machine shop and turned down on a lathe. Worked perfectly. You can see it in this photo, although its not a close up.

[Bill Verburg]

After speaking w/ a # of RS and Cupcars owners and looking at their engines over the years I had never seen a stock 964RS or Cupcar w/ other than the 3 sheave harmonic balacer version of the crank pulley(nor is there another part # listed anywhere that I can find). Then this past weekend I was talking to John Colesante at the Club races at LRP. John has a beautful all original 964RS Cup and lo and behold,

I believe the car is stock right down to Matter roll cage and jack mounts (Did I mention that it is a really, really nice example!!) Very tough run group as well, they provided the most entertaining race of the day.

On a 993 you can do the crank and alternator setup as on mine


The 993 does not incorporate a harmonic balancer in the crank pulley so there are no issues w/ swapping the pulleys as on the 964.

Bottom line, I would only do the alternator/fan mod and discard the alternator tender while in there.