Okay I have an important question to ask. I will be having a motor built in a few months by AED in Norcal. I will be running a 8.5:1 compression motor in my 2000 GT with Patriot stage 2 heads and custom grind cams. I will be running a vortech Si trim with a custom air to air intercooled blow through setup. I'm looking at getting 450hp daily and was wondering what size pulley I should run to reach my goal. I know the low compression and intercooler means I need to run more boost. At the same time the heads and cams will net be major gains with it being blown. Looking to run about 13-14 psi post intercooler so ~16 before the intercooler. Running on 91 octane california piss water so 8.5:1 will be the compression no matter what. Its critical that I get the right pulley size since its a complete pain to swap pulleys and belts on these blowers especially on a tuning day.
What Size Vortech Pulley?
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99% of engine builders and dyno guys will tell you that 8.5 is to low for a centrifigul blower. However if you are having your car built and tuned by AED they wont tune a supercharged car with more then 10psi of intercooled boost with a compression ratio higher then 8.5 as I recently learned.
but to answer your question a 3.25 will probably get you to 450rwhp if not swap on a 3.12. But if you are looking for 14psi or so you will need a 2.87 and you should exceed your goal.
but to answer your question a 3.25 will probably get you to 450rwhp if not swap on a 3.12. But if you are looking for 14psi or so you will need a 2.87 and you should exceed your goal.
Hit the nail on the head
You can probably run a 3.3 or 3.1 and get 450 at the wheels easy, but if you want the boost you want, you will need to run a 2.8" pulley, but then you are probably talking around 500 at the wheels....but hey...nothing wrong with 500 at the wheels 
I recently looked into piecing together an 8 rib setup that way I won't have to worry as much about belt slip. Shaun definitely wants to run the 8.5:1 so I'm gonna have to run some better gears to make up for the lag from the low compression. He also told me it might be a good idea to run a boost controller and a really small pulley that way I never have to change pulleys but still run 450 or 500+ whenever I feel like it. I might go this route if I can save money piecing together the 8 rib rather than spending the 500 or 690 from a place that sells the full kit. Thanks for the help guys.
I wouldn't get it tuned or built by anyone else since these guys are pretty much the best when it comes to shops in california. They have built several GT's that push anywhere from 400 to 700hp as well as several cobras and have yet to have a failure on tuning or building. 9:1 compression would limit the amount of power I could run on 91, plus 8.5:1 will not be too sluggish at all with the ported heads, cams, and gears. I should see boost around 2700 with the Si trim as well as the 8 rib setup so the sluggish feel will be gone very fast.
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