<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Induction Concepts:
Stick with the roots type (magnacharger, whipple, kenne bell, etc.).
...where a roots type blower makes boost right off idle and has a nice, flat torque curve like turbos.
Roots type is the better choice for your application. </div></BLOCKQUOTE>
Ummm, I'll go easy on you since you're a turbo dude but the only true Roots-type blower that you mentioned is the MagnaCharger (based upon an Eaton 112 rotor pack). The Whipple and Kenne-Bell are both actually screw-type superchargers. A fair bit of difference as the screw-types tend to produce roughly the same torque characteristics down low but don't drop off as much up top as a true Roots blower does. That and the screw-types actually use the rotors to compress the air whereas a Roots-type blower uses the case to compress the air. And last but not least, the screw-types are manufactured with minimal clearances between the two rotors, whereas the Roots-type rotors actually touch one another thereby increasing the amount of heat added to the air charge by the blower due to friction. Additionally, because of this rotor contact a Roots will also rob a bit more hp to drive it...
The screw-type blowers are by far the better choice but for a blower that may never see the high side of 8 psi I'd go with the Roots-style MagnaCharger.
Can you also throw up a few dyno pulls of some turbos? Of the few hundred that I've seen they tend not to make the big torque numbers until they spool...I've yet to see a turbo dyno that produced a flat torque curve unless you're only looking at the portion of the graph after the turbo(s) has hit maximum boost.
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