I was just wondering what you guys think of putting pulleys on my car. I was thinking of going with the march crank pulley, they also sell one with a alternater overdrive pulley to keep the ampage up I guess. They claim up to 12 hp with just the crank one on a lt1. Is there a risk/benefit factor or is it a good thing to do? thanks!

 

The risk you run with underdrive pulleys, is the fact that they will hurt your charginf system. They may cause your car to charge slower, draining the battery.

I highly recommend them. Now I dont know how much different on the Fbodies they are, but I noticed a difference on my car! Go for it, and you shouldnt be disappointed!

 

Eh, pulleys are alright. They're cheap at least, just don't expect much from them maybe 3-5 hp. I've had the March 2-piece on my '89 for a few years. I didn't feel any difference and charging kinda sucks but it isn't too bad. Cooling also suffers so keep that in mind.

 

My crankshaft only powers an alternator so I just use a pulley that fits. I'm more concerned with the alternator rpm at 6800 rpm than I am with what size pulleys to use.

The idea of the underdrive pulley is to slow down the accessories so they don't drag so much. The downside is that the water pump turns slower (not enough cooling), the alternator turns slower even with the larger alternator pulley (as mentioned above charging system is poor especially at low rpms).

The idea in theory sounds good but for most people they won't see a big difference except for the poor charging at low rpms. 3-5 hp increase is a high estimate. I doubt most people would see an extra 2 hp during normal street use.

 

I figure I'll be better off putting that money towards headers. I 'm also going to need some DR's and maybe some LCA's. The guy at my race shop told me he doesn't sell [coated] headers, is there a reason for this? Thanks guys!

 

Some people don't want to spend the extra money for coated headers. Other may modify the headers for O2 sensors, crankcase evac or EGT sensors before getting them coated.

 

Keep in mind that March has their Power & Amp setup that uses a smaller crank pulley along with an alternator pulley that will speed the alt back up to get normal charging.

http://www.celligent.com/tim/iroc/LE...y/DCP_1910.JPG
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Tim

 

I have the March 2-piece set and had very little if any loss in charging. I noticed I picked up around 1 MPH in trap speed on average after I added the pulleys.

 

A bigger alternator pulley (like the march system) slows down the alternator even more. It does not speed it up at all, but the alum pulley does lighten the rotating system a little.

 

Exactly. That's why the Power & Amp kits come with a smaller alternator pulley.

Tim

 

Underdrive pulleys can help prevent tossed belts, if that's a problem. Happens more with v-belts than flat multi-groove, though.