Rick

I just saw this on Ebay - Auction for Power Pulleys - especially the comment about "Dyno Proven 7HP Gain and 7ft. lbs. of Torque!".

Has anyone done this modification? Results?

Thanks much.

turbo944

This was discussed recently and in fact, Danno or someone went into detail about what and where you could expect gains/losses with them. Turns out that they are not worth anything on these cars. You might do a search for more details.

fast951

Rick, The pulleys look nice (pretty color). You might want to request the before and after dyno charts. Also, is the 7hp/tq gain the same on 924S, 944, 951... I have no experience with the products, but would like to know.

Dave951M

To nit pick here a bit, underdrive pulleys do not "make" more power. They reduce parasitic loss. I'd be very skeptical about a 7hp change, more like 2 at most.

po9rs5che1

I don't have experience with these. However, when I purchased my '88 LX 5.0 Mustang I installed a set of JBA Underdrive pulleys. Crank,water pump and alternator. These pulleys reduced my 0-60mph times .2 sec upon installation. Sameday testing with a VC200 Vericom computer. My car had G60 soft compound tires which yielded 1.8 60ft times (Traction was not a problem). Having said that, I would say outside the HP/TQ claims they might still offer some performance increases. I don't know if I would pay the kind of money they are asking for those pulleys for what my gains would be , but if someone had them for about $150 I would definitely consider the purchase. I guess because they go on a "Porsche" they can get an extra hundred or two. If someone had a set and was willing to do some reverse engineering. I have access to CNC high speed machining centers . Just a thought.. and my two cents worth..

Ken

My friend has an 02 Mustang GT and all the people he knows with the pullies on their Mustangs have seen gains as well. It's pretty proven to work on Mustangs.

Having said that, the design on the 944 pully system is very different. From what I remember of the old post(and what Danno and Iceshark said), basically things like the power steering and alternator are underdriven almost as much as they can go and still function properly. Perhaps there's 10% of overdrive. The Mustang accesories are overdriven more by their initial design, so more power can be gained there. Plus the AC has a clutch that disconnects when not running so it causes very minimal losses(1/2th of a HP?). Finally, I don't think there's much weight to be lost off of the pullies as the factory ones are pretty light already. (Not like the one on my Subaru, where you can save 7-10lbs off my crank pully.)

Unless someone can provide some good dyno runs with significant gains, they seem to not be effective.

po9rs5che1

I should have known that Porsche would have already concidered this aspect of parasitic losses. :-) Thanks

Jeremy Himsel

One thing to take note on with the Mustang pulleys is that they are reducing the parasitic losses on 5 systems (AC,Alt,PS,WP, & Smog Pump) where as the the 951 only has three and the A/C really doesn't count unless it's in use. I've seen dyno gains on Mustangs of less then 10 HP with underdrives. I'd challenge the 7Hp claim on a 951.