I've got a GS auto, this is my first car, and I for one am not really too sure on what I want? I'm assuming the pros of light-weight is that it's...well...light weight =P. What's the pro on under-drive? Without that massive amount of flaming I am TOTALLY expecting right now =P.

:00000732:

don't worry, flaming isnt tolerated in the tech areas of this board.

underdrive = smaller crank pulley and larger accessory pulleys. they are designed to alleviate some of the power robbing effects on the engine from driving the accessories

lightweight = light weight. by reducing rotating mass you create the same effect

I want you to read this article, click here. before you purchase and sort of underdrive pulley for any car.

ok well look at it this way....I have a brand new unorthodox racing underdrive crank pulley sitting in my room right now as we speak. It's been here for about a year now and I have absolutely no intentions of ever putting it in. They're mainly made for actual race cars so the accsesory belts don't get burned up during heavy racing. The problem with it and a daily driving car is that it slows down all your belts so you get more hp going to the wheels/crank whatever, but this also slows down your serpentine (alternator) belt which could cause your car to turn off while driving and it could also cause the alternator to not spin fast enough to charge up your battery leading to.....a dead battery. If you still want it I'll sell you mine for 60 bucks plus whatever shipping is to wherever you live.

They will cause vibrationwhich will lead to a dead motor unless you do a full rebuild and balance the whole motor to compensate for the pulley.

A lightweight flywheel / harmonic balancer gives your engine less rotational enertia and stop and go traffic will make you stall like a 16 yr. old with a permit. It does free up some torque, but keep this in mind. Underdrive pulleys are overrated, but do help with responsivenes. It'll help, but it will also take some getting used to.

Are you talking about guys with sticks or would us auto guys have to deal with that littls glitch too?

both.

i never had that problem with mine lightweight underdrive and that was on top of .374 lift cams that barely wanted to idle to begin with.

a lightweight flywheel yes, but not the balancer

Thats what I meant. The Flywheel'll make you stall easier, and the underdrive is overrated. Both will add a shmidge of torque, but your engine will feel more responsive with the lightweight flywheel.