[serialk11r]

Not as a "windmill", but as a turbine. As I noted in the second post, it doesn't work very well unless the rotor chamber volume is significant compared to the intake manifold volume.

Ideally you have a mini-supercharger placed where independent throttle bodies go, then it would work. Otherwise there is too much blowdown loss. If the supercharger were electrically powered it could have very good transient response too.

Unfortunately you can't really do this if you want boost since an intercooler has to go somewhere in there and such. Additionally, say you take an Eaton M62 with ~1L displacement, with 6 lobes that makes only 0.166L displacement per lobe, so it will depressurize quite a bit in the manifold which probably has a lot more volume than that. If you use a giant supercharger and turn it slowly that would work better, but turning a supercharger too slowly is bad for boost efficiency, although having reduced intake manifold volume is good for boost efficiency.

I was thinking a twin small supercharger setup where you can bypass one of them and disconnect it from the manifold altogether when under light load circumstances, but the remaining supercharger would have so much blowdown loss that the parasitic loss from running the supercharger would probably overcome whatever tiny gains there may be from throttling reduction.