Actually, I couldn't find the original memo so I linked to the> conversation that referenced it.>

In any event, the little piece of rubber between the two halves of the> crank pulley isn't a harmonic balancer.

yes it's much lighter, however the main advantage is> diameter (underdrive means easier to drive> compressor, alt, p/steering, --less effort but they do not> spin as fast either.> first question, will this affect p/steering, a/c, & alt> operation???> answer---no noticeable change, except more> power. after 2 years, i have had plenty of juice even at> idle, to operate all i need, however i've never been> the type to run stuff at idle that i do not need to be on.> the beauty of this is that power gain is at> ALL rpms, so driveabilty is better especially at lower> rpms where turbo is lagging. vishnu claims 5-10HP> which sounds about right.>

jellymax>

http://www.spdusa.c­om/pulley_kit.htm

Are there any benefits in going to a lightweight crank pulley. I'm coming >up for the 75000kms inspection on my 03 WRX and figure when have belt >changed can change pulley at same time. Any drawbacks to having lighter >pulley as well? Any makers better than others? >

The light weight pulley is used to reduce the rotating mass or > inertia> of the motor so there is less resistance to rapid speed changes. > That> can help race motors to respond faster. How much benefit there might> be on the street is questionable IMO.>

The underdrive pulley reduces the speed that belt driven accessories> run. Alternators, AC compressors, etc use engine power and the > slower> they run, the less power is lost driving them. The power increases > are> smal;l but measurable, but there is a direct price to be paid. Your> accessories will not run as designed, eg: your alternator will put > out> less amps and batteries will charge slower or you will have to turn> down your 3000watt stereo.>

Philip>

On Thu, 31 Mar 2005 10:40:46 -0500, "jsteve1109"> <jsteve1109@rogers.­com> wrote:>