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Clutched supercharger with an engage knob - just like in the Roadwarrior? Can't wait.
 

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IF that is the case and it turns out to be true, I will be thoroughly impressed. What that means is that the MPGs will not take a huge hit. I've always known about SC with adjustable boost levels, but have never seen it done from the factory. I have never heard of that with the ZR-1? I'm still skeptical that this will be the case with the Hellcat. 160HP seems like a huge difference to me.
 

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The only way to change the hp that much on an OHV engine is with adjustable boost. With a turbo it would be easy to do by controlling boost electronically.

The supercharger must be clutched because there would be no reason to have a pulley sized for say 16lbs of boost only to allow a bunch of that boost to be bleed off for a lower hp rating.

That wouldn't help mileage at all because the supercharger is having to be spun just as hard but the excess boost is just blown into the atmosphere. That would make no sense other than a valet type of reason which would be ridiculous.

Should we start a turbo Hemi rumor next. ;)
 

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Blowers can use an air bypass valve. It allows unboosted air to flow around the blower and lessens the pumping losses. One of these and/or a variable speed drive or clutch on the blower could be used to control engine output.

From Whipple's web site: " The best kept secret in forced induction is the little known air bypass valve. This small valve, when properly installed between the supercharger and the throttle body, allows the supercharger to become extremely efficient in terms of economy and parasitic power loss. Our 1600AX supercharger uses less than 1 HP at 65 MPH cruising.

The bypass is operated by a vacuum actuator control unit that is normally closed. When vacuum is high (idle-cruising) the actuator opens the bypass valve, equalizing the vacuum pressure throughout the system. When boost is required (accelerating) the vacuum is decreased and the bypass valve instantly closes, causing pressure to increase into the cylinders. This equalized vacuum condition virtually eliminates the normal parasitic power loss of a forced induction system.
"

There's no reason this valve couldn't be controlled electronically.
 

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It would make a lot of sense to put a bypass on a root or twin screw, they get hot in low rpm and you can't use the boost at low RPM anyway. In normal driving you really can't use that much HP before you lose traction, so programming the supercharger for usable power is by far the most important aspect. Hopefully they will throw in some nice innovations than your standard bolt on blower!
 

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Blowers can use an air bypass valve. It allows unboosted air to flow around the blower and lessens the pumping losses. One of these and/or a variable speed drive or clutch on the blower could be used to control engine output.

From Whipple's web site: " The best kept secret in forced induction is the little known air bypass valve. This small valve, when properly installed between the supercharger and the throttle body, allows the supercharger to become extremely efficient in terms of economy and parasitic power loss. Our 1600AX supercharger uses less than 1 HP at 65 MPH cruising.

The bypass is operated by a vacuum actuator control unit that is normally closed. When vacuum is high (idle-cruising) the actuator opens the bypass valve, equalizing the vacuum pressure throughout the system. When boost is required (accelerating) the vacuum is decreased and the bypass valve instantly closes, causing pressure to increase into the cylinders. This equalized vacuum condition virtually eliminates the normal parasitic power loss of a forced induction system.
"

There's no reason this valve couldn't be controlled electronically.
That's not unique to Whipple. Almost all positive displacement superchargers use a similar system. It doesn't vary boost at all though. All it really does is basically lets the supercharger "freewheel" when just cruising so you get better mileage because the engine isn't using a bunch of hp to spin the supercharger. GM even used this way back on their 3.8 with the Eaton.

Anytime you are into the throttle this has no affect. It's either in vacuum or not. It doesn't magically allow different boost levels.

In other words this will not change the hp output of an engine what so ever.
 

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