SHELBY GT 350 Member
Joined: Sep 2010
Location: see user name
As far as choice in blower - centrifugal or screw, really just depends what you want. They both have different characteristics; with a centrifugal blower, typically they do not produce any boost below 3K rpm, but when it hits they produce an increasing amount of boost that coincides with engine speed. Up to a certain point anyway. With a screw blower, they begin producing boost almost right off idle and hit their max amount of boost earlier in the rpm range and stays there.
If you compare dyno charts for engines running the two different kinds of blower, you'll see that the power curve for a centri just keeps climbing as engine speed increases toward redline, and with a screw blower it will have a much flatter curve - power increases sharply early on, say between 3000-4500 rpm, and then it just holds there.
All that said, screw blowers tend to be the more lusted after of the two due to the rush of power that's just instantly there, but many of the more powerful or fastest cars you see on a dragstrip are running a centri blower like a Vortech YSi Trim.
I think your stated goal of 450rw is reasonable and will make for a very streetable car. Lots of people daydream of bigger numbers but forget that all that power can also have a negative effect of driveability. There is such a thing as too much power. Be sure to do your homework as well on chassis/suspension and braking improvements, in the hope that your final result with the build will produce a well balanced automobile that makes killer power and can effectively put it to the ground.
2001 GT Convertible
All the usual bolt-on's /200 I6, C4
And a few Explorers too... 2008 4.0 XLT 4x2, 1996 XLT 5.0 4x2, 2003 Sport Trac XLT 4.0 4x4