Underdrive pulleys...Opinions?

[PorscheG96]

Haven't heard too much about these for Porsches, mainly the mustangs and camaros...Ahmet mentioned reducing parasitic loss of power to alternator/AC/powersteering components in the past but people seemed skeptical that much power was to be had. Broadfoot has a set of pulleys for each of these accessories that would keep them operation but reduce power loss during operation, anyone have an opinion on gains? -Trevor

[wolfrpi]

probably no gain - the stock pulley is apparently very light to begin with. most of the gains are a resultant of reducing rotational inertia and because the smaller pulley is only marginally lighter the results will probably be minimal.

The reduction in drag is apprently not where the real power comes from (marginal). Check out unorthodox racing's homepage for details and comparisons of the original 951 pulley and their version. May be interesting to run a comparo though and see the results.

[drew1]

Some ads say you're saving power by not turning stuff like water pump, alternator, power steering & AC as fast.

In a 944 the water pump is turned by the cam belt so no help here. I think the voltage regulator limits the power pulled by the alternator to what is needed so the only help here is slight gain in torque not having to acelerate the rotor as much. With AC off, you're just turning the clutch, so just gain inclutch aceleration here. There may be a gain in the power steering, but I'm not sure. It seems that just enough power would be required to open the pump relief valve then the fluid would be free flowing. Maybe a slight gain here.

Maybe somebody with experience will post.

drew1