Great interview with a guy from Garrett about global TC business and technology.
Particularly interesting is the concept of aggressive 50% downsizing with e-boosting. KERS equipped cars with high voltage should be particularly suited to such practices.
I'm wondering if e-boosting or turbo compounding in a hybrid turbo charger would not be the best solution. You do have some losses by the generation and the electric motor but you would not loose any energy by a waste gate and could harvest much more energy from the turbine than the engine needs for charging.
About modern turbo methods.
- Twin turbos help with the turbo lag problem.
- The use of variable vanes to control the aspect ratio can totally eliminate turbo lag. Disadvantage; no total energy use of exhaust gas possible. http://www.autozine.org/technical_schoo ... _3.htm#VTG
- You can use e-boosting with an electric high speed servo motor/generator on the TC shaft to already run the compressor up to boost speed while the engine is being fired up. The engine will not experience any turbo lag at all through the complete operating range. http://www.ecomotors.com/mechatronik-division
- The same thing is obviously possible with a hybrid turbo charger where the turbine and the compressor are not on the same shaft but connected to individual electric motor/generator units. This option is particularly useful when you want to avoid additional space and weight for connecting the intake and exhaust manifolds in one unit and are prepared to incur the additional weight of one electric unit. It opens the additional option for extremely asymmetric power specs between turbine and compressor. http://en.wikipedia.org/wiki/Hybrid_turbocharger