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Message: <blockquote data-quote="Hellion94" data-source="post: 680743" data-attributes="member: 8471">Re: In Response to Javi's Post....Modo is right, basically a Roots or Twin screw will be an off-idle to 4,500 - 5,000 (on a 5.0L) or so type blower. It'll make instant boost, tons of torque and power down low, and taper off as it runs out of efficiency at the top end. A centrifugal is basically a turbo compressor that's driven by the crank, so it actually relies on RPM in order to create boost, because it's impeller needs to be at a certain RPM to create full boost. (I know that sounds weird, all blowers are driven by the crank, however a Twin Screw or Roots has a completely different construction and compressing style, and doesn't depend on high RPM to make boost). So, in essence, a Centrifugal will make peak boost at the moment you shift, as the boost will continue to climb as the RPM's increase. This doesn't mean that it doesn't make any boost before peak RPM, just that the boost is linear, meaning it steadily increases as the RPM's rise. This is why centrifugals have such a strong top end, because they just keep making boost. So a centri. would be more of a 2,000 or 2,500 to redline type powerband. Now a turbo will function completely different. Since a turbo's impeller RPM isn't limited by the crank (because there's no belt), it can basically spin as fast as it can possibly spin, and will increase in RPM as fast as possible. The only thing limiting a turbo's boost level is the wastegate, so a turbo will spool up, and then the wastegate will limit the pressure on the turbine (exhaust) side of the turbo, limiting it's RPM and controlling boost. This means that turbos come on hard, from no or very little boost to full boost in a couple hundred RPM, usually in the mid range RPM level, and will pull hard up top as well (as long as they are properly sized for the engine).</blockquote>