Re: Info on Underdrive pulleys

[Stewart MacLund <sundie@lunaticfringe.org>]

Uhm.  If the pulleys are smaller, that would mean that the accesories turn
faster....  Which would rob the engine of power...  The pulleys diameter
should actually be bigger, yes?


Sundie

Billy T. wrote:

> Underdrive pulleys replace the pulleys that drive your accessories, like
> the a/c, alternator, power steering, etc.  All of these things are spun
> by the serpentine belt, driven by the crank.  By putting the underdrive
> pulleys on the accessories, you lessen the drag on the crank in two
> ways.  First, the pulleys themselves are aluminum and lighter than
> stock, therefore ruducing the mass that needs to be spun.  Also, the
> pulleys are smaller in diameter, and don't spin the accessories as
> fast.  Your A/C will still get cold, and your powersteering will still
> function as normal, but the crank will not be slowed as much by these
> items.  Think of an engine with no a/c or powersteering...  this is a
> more livable solution.  V8 guys have had these things for years.  As far
> as hp gains, the VR6 may gain as much as 12 hp.  This was an estimate
> from a VW tech that is a friend of mine.  For 179 dollars, it would be
> the cheapest most effective power upgrade for a VR6 available.  As far
> as the 40 hp increase, I believe in some big V8s and high boost engines,
> it is very possible.
>
> Billy T.