I've got a 92rs 305 and thinking about them.

1. Do they really gain you between 8-15 hp

2. Are they worth the cost?

3. If so which ones are better than others?

 

Is this a car for the track only , whose most running time is spent at high RPM ? Sure , sounds like a way to free up a pony or few . 15 HP is kinda optimistic , but there would be at least some gain .

Is this car driven on the street at all ? Forget them ! They will have your waterpump and alternator turning too slow at the average RPMs a street car will be doing . Tell me , ya got a Bangin' sound system in there ? If so , with how hungry Subwoofer's Amps are , why would you want any part of slowing your alternator down (crippling it's output) ?

 

I did a lot of reading on this subject a few years back, as well as having second hand experience with many of my fellow club members using them. ....and most ended up going back to standard.

Obviously, by design, they turn your alternator, power steering and water pump slower. ...so...you potentially lose efficiency in those areas. Some more important than others of course. ...and of course, you'll hear some people who hated dimming lights or hotter run temps, and other people seem to have no issues at all.
....and they do gain power, but again, whether or not it's noticable without being at the track or on a dyno is debatable.

....at the end of the day, my thoughts are that unless you're racing fairly seriously, where every pony counts, I'd put money and effort in other places.

 

Nope, they're not.

 

If you buy the march power and amp kit it keeps the same ratio for driving the alternator and waterpump. It includes smaller water and alternator pulleys to spin them faster after reducing crank size

Motor will rev faster with the reduced mass. I like them. I saw about a .05 sec et gain but hard to say since weather could have changed things

 

Wow, that's good info. It's only a daily driver and the amp and subs portion of the stereo will be a Christmas present to my daughter, so I see what your saying about reducing output, however will the amp series from march would be the way I go if I do this. It's just something I saw I thought would be neat, not say it's needed but cool. Also do I have to include this in my tune info when I get my chip done?

 

If you add stereo, i would suggest a 140 amp alternator upgrade and def use the power/amp series pulleys with the smaller alternator pulley

I ran a stock L98 with and without the alternator pulley. Stock alt pulley and underdrive crank pulley had charging issues at idle. Once i added the smaller alt pulley from the kit, no more charging issues

 

I don't feel like buying another alternator. Will changing just the crank pulley help or is all or nothing?

 

It will keep stock amp rating output but its only like a 90-105 amp alternator.

I thought subs and stereos sucked down power? It may not need it i dont know how much power an amp, speakers and headunit draws

 

An extra 150-200 can be spent on something better...you're right

 

Glad I ran across this thread! Was looking into buying a set, but my car will never see track time so I'll stay with the stock ones...