Compound turbocharging is when a small turbocharger and a larger one are both used on a single engine, the small turbocharger creates 'boost' faster at lower engine rpms, and the larger turbocharger creates more 'boost' at at higher engine rpms. (If I didn't explain that properly, please tell me.)
My
idea is a turbo that (I hope) will be able to achieve the same effects, including performance, as two separate turbos used for the same reason.
Inside the turbo unit would be a turbine and impeller connected by a hollow 'tube-like' shaft. Through the shaft would be a smaller diameter, but longer shaft, with the smaller turbine and impeller at the ends.
The turbo would have the same number of inlets and exhausts, in the same locations as a normal turbo (approximately ).
The larger turbine and impeller would have a similar shape to existing turbos, and the smaller turbine and impeller would be designed more for tubular gas flow.
The exhaust gases will have to flow through the slower moving, larger turbine blades before it spins the smaller turbine blades. And the intake air will have to flow through the slower moving, larger impeller after its gone through the small impeller to get to the intake manifold.
This unit would be cheaper than buying two separate turbos and the extra piping. And it will save space.