The only ill effect you'll see with a 25% underdrive is the IPC illumination lites go dim on hot summer nites at red lites when you have the A/C on high and the radio blasting. If you can live with that there is no need for an overdrive pulley on the alt. I've installed both the ASP and Powerbond and never had a problem with either one. The Powerbond is SFI rated. I like the idea of the ATI being bolted. Can you imagine the damage that could be done if the crank pulley came apart at 6K RPM. The satisfaction of knowing the ATI isn't going to come apart justifies the extra cost.

 

Using an OD pulley on the alternator only costs you about 1-ish HP.

 

Ask yourself how much time overall you spend in the senario I mentioned above. Probably not much. If you can live with that you don't need the overdrive pulley on the alternator. Once your RPM is over about 800 your battery is being charged so you don't need the overdrive pulley at that point. If you add the overdrive pulley you lose the underdrive advantage ALL of the time whereas if you don't use the overdrive you only have a reduced charge rate at idle speed which isn't the majority of the time. The advantages of an underdrive pulley are too many to worry about dim dashboard lites. Your paratsitic devices last longer because they spin slower(all of the time). Horsepower that was being wasted overspinning them now goes to the rear wheels which increases fuel economy and puts the formerly wasted power to the ground. It it wasn't for the dash lites dimming the OEMs could use underdrives directly from the factory.

 

I got powerbond pulley 25% works great and heard there one of the best!

 

Who has the best deal?

 

People keep talking about the ATI being better cause it won't fall apart. But the two years I've been on this site I've never seen anyone post about their under drive pulley "falling apart". Feel free to tell me wrong if I missed one. I've heard of pulleys throwing belts, which is why I recommend the SLP pulley because of the extra high retaining walls.

Even if a pulley falling apart was a concern, I'm sure it's more of an issue for racing teams like stated earlier where the engines have crazy high hp.

 

ASP is what i have.....on both SS's

 

Some people heat their pulley up in the oven before installing it. I know this is an interfereance fit, but I've never been able to talk myself into using heat. Heat may not be a problem with the ATI since it is bolted, but since the others are pressed together with a rubber bushing in between heat makes me real nervous. The pulleys that come off are usually FI engines(belt driven impeller). The interference fit doesn't provide enough purchase to keep the pulley from spinning on the snout of the crank. These applications require pinning. If that pulley comes off or apart at high RPM only bad things can happen.