Rotrak variable supercharger
 

looks like a great idea

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interesting...

But will it go "TSUUUU TSUUUU?"

Nice animations, makes sense. I think designs like this have been around for a little while, they were just cost prohibitive.

that was just way too vague to take anything away from. i just cant see that being effecient with all that transmission jazz. if it worked, we probably would have seen it before. pretty neat concept though.

I doubt it, the design looks more like a centrifugal supercharger which doesn't have a whine.

Meh not very interesting.
Say you use 2 smaller Roots superchargers, which each pump slightly less air than the engine does. If instead of a bypass valve, you shut off air to one of them, the other becomes an "air motor" and will recover pumping losses at low speed. I'm waiting to see this applied somewhere...if air is not shut off, then you get boost.

No, but it will go Pssssht!

Centrifugal superchargers and toroidal CVTs have both been around since forever. But this is the first combination of the two that I have seen (though I've been hearing rumors about this particular product for a few years now). The only thing that comes close was a two or three speed gearbox IIRC.

Toroidal CVTs and traction drives are actually quite efficient. I'd be very surprised if there were even a 10% loss. So with the improved adiabatic efficiency of a centrifugal compressor compared to a roots or even twin screw SC, it would still be less of a parasitic loss than conventional supercharging.

A bypassed roots blower saps very little power from the engine. Seriously, dude, we've discussed this. And even if it was massively parasitic, your idea is fundamentally flawed, blowers don't run in reverse.


It boggles my mind how you guys can't see how badass this has the potential to be. It would literally be a centrifugal SC with more low/midrange torque potential than a turbo. Think 20+ psi of boost from idle to redline with no lag, and the adiabatic efficiency of a turbo.

The only problem I see with this is the toroidal gears in the transmition. While tey are the cheapest, they will wear out the fastest. Magnetic cvt on the other hand would be PERFECT for this application

no no old greg, a roots blower with negative pressure across it would produce positive work...do you see what I am talking about? Typically at part load you draw air through a throttle to reduce intake density. If the throttle were replaced by an underdriven roots blower, then at the same manifold vacuum, the roots blower is adding extra shaft power to the engine.

I know that a roots blower doesn't sap power, we did discuss it and it's pretty obvious why, I'm saying not only does it not need to sap power, it can improve efficiency by being like a turbine restricting the intake while producing some work, rather than heating up the air. Roots blowers are symmetric in some sense, so how can it not "run in reverse"? I'm not even claiming that it is efficient, but it should be much better than a throttle which has 0% efficiency.

EDIT: okay I take back a small piece; because of the nature of the Roots supercharger, blocking off the intake wouldn't work. So a variable ratio drive on a larger supercharger, or a clutch + blocked off inlet.

From the way you first described it, I thought you meant ditching the bypass valve rather than the throttle. Then somehow recovering the parasitic losses by having the intake air exit out of the second blower. You can see how this doesn't make any sense.

A throttleless roots blower with a cvt is an interesting concept, assuming the cvt can be backdriven. But then, just using a diesel engine would be a lot cheaper/easier. :)

Or, if the automakers fitted continuously variable profile camshafts. But we all know they're too cheap to do that until regulations force them to.