Underdrive Pulley

[Steve Dionne]

I am entertaining the idea of installing an underdrive pulley on my 98. What are the advantages and drawbacks,(if any) who makes them, etc.? I have read that they improve HP. Is there an actual gain or do they just free up HP usually reserved to turn the accessories?

 

[Ian Macoomb]

Steve Dionne:
I am entertaining the idea of installing an underdrive pulley on my 98. What are the advantages and drawbacks,(if any) who makes them, etc.? I have read that they improve HP. Is there an actual gain or do they just free up HP usually reserved to turn the accessories?

Well there is the one known case of the ASP pulley coming apart. Can you even get the ASP pulley any more? The SHO Shop pulleys required modifying before they'd work on my car (I still don't have them on 2 years later) and can you even get these any more? I bet the SHO Slop's website says you can and if you can ever get a hold of them they'll probably say they'll have one made up. They'll probably charge your credit card right away and send you a pair of pulleys that don't fit 6 months later.

Aside from the vendor issues, I think that they're a very underrated mod.

 

[SHOZ123]

If you contact ASP they may make one. I have the single crank pulley and it's gone through at least 50k miles. I have a VAK too works as good.

 

[Tunez]

I have one of the VAK's here that I ordered for a friend and he ended up selling the SHO and told me to just keep it. It was never installed if you are interested. I am very pleased with mine too.

 

[SHODWN]

Steve, I have them installed on mine. The ASP Crank, The Power steering, and never noticed a difference.

I would use "Pauls" VAK if I ever built another car, Seeing that neither GIVE you HP they just free some up under a WOT condition. Plus if you were able to get a set that really did fit, you could install 3 VAKS in the time you installed one ALT pulley..

 

[Steve Dionne]

Thanks for the help fellas. Looks like the UDP is out. The VAK, as I understand, cuts off the accessories at WOT. Is this correct or am I making a bad assumption? Are thye easy to install? What do they cost?

 

[Mr. SHO]

Steve Dionne:
Thanks for the help fellas. Looks like the UDP is out. The VAK, as I understand, cuts off the accessories at WOT. Is this correct or am I making a bad assumption? Are thye easy to install? What do they cost?

The VAK differs a little bit depending on application. It cuts some accessories at/near WOT. For the Gen 3 SHO, it disables the VAPS (cuts PS boost), cuts the A/C and fans, and cuts the alternator output. If you don't have VAPS, obviously it doesn't do anything to the PS boost. Paul can give you all the nitty-gritty for your specific application.

Install time should be under an hour. You splice a vacuum tee into one of the lines on your manifold and attach the VAK's hose. Then there are 3 sets of wires (maybe more/less on different models) that get spliced into the engine's fusebox. Then you hook up the ground and power, and you are good to go.

The real beauty of the VAK is that it only disables the accessories when you floor it. So you still get full operation of all the accessories under normal driving conditions.

 

[Tunez]

I went with the VAK because I also like to have some kind of half way decent system as well. Like I said, I have a brand new one sitting here that I had ordered for a friend. I have the installation CD and everything that Paul sent with it as well. I have no need for two so I'll let it go at a pretty good price. PM if you are interested and we can go from there.

 

[MarkieSHO]

I have teh ASP UDP and its 'Aight', how much of a difference would i notice with the VAK?

 

[SHOZ123]

More than the UDP.