[Irace86.2.0]

Originally Posted by FR-S2GT86

I've been pondering this for quite a while now, but thinking of the positive displacement supercharger set ups that are available for the twins:

What if one could reduce the parasitic load on the engine that the supercharger draws, to almost nothing as engine RPM's increase, by installing an exhaust-driven turbine in addition to the supercharger, which spins a gearbox, which then spins a pulley to drive a belt that spins an overrunning clutch pulley, which is mounted to the supercharger's drive pulley?

In theory, at low engine RPM's, the supercharger would be providing the immediate low-end boost and as the RPM's increase, the turbine gradually spins up and takes over the torque demand of the supercharger.

The key part would be the overrunning clutch pulley to allow the engine driven belt for the supercharger to initially spin the supercharger's drive shaft, and then as the turbine and its gearbox gradually takes over, the turbine assembly's belt would take over, spinning the supercharger's drive shaft, but just BARELY faster than the engine's serpentine belt would at top RPM.

Something like this:

which can be found here:

https://www.hilliardcorp.com/overrunning-clutches/

This set up could again, in theory, eliminate the parasitic draw of the supercharger, increasing available torque to the drive train.

Basically, this is a turbine-driven, positive displacement (this could even be applied to a centrifugal) supercharger with little to no parasitic loss to the engine, combining the two best advantages of both a supercharger 1) immediate low-end boost from the engine, and a turbocharger 2) free horsepower and torque from the exhaust gasses.

This is not twincharging, as the intake air is not compressed in two separate stages.

The only disadvantages of this set up that I can think of would be 1) slightly more weight, which would be immediately negated by greater available drive train torque, 2) higher under-hood temperatures, which can be dealt with as one would normally do with a turbo set up, and 3) a slightly more complex set up.

I think this is totally do-able with the right parts, which are already available, and by a persistent and innovative individual (with obviously deep pockets).

When you say it could be added to a centrifugal supercharger, well, then isn't that just a turbocharger that is more complex and inherently less efficient? Most manufactures would probably just add an electric supercharger or mild-hybrid system with a belt alternator starter (BAS) to torque fill down low and then use a traditional turbocharger for up high. This is what multiple manufactures are doing.

https://www.greencarcongress.com/201...180411-a6.html

I think the best, simplest and most elegant supercharger solution that was already mentioned is the electronically-controlled, variable-geometry pulley, which can essentially create a small-pulley high-boost-map for more power down low, and it can taper off boost by creating a large-pulley low-boost-map for less power up high. This means the supercharger never has to over-spin or bleed boost.