fritz:
RC:

I am also curious why Porsche didn't actually adapt the VTG turbo charger technology for their Panamera top models.

There's less benefit on an engine with a larger cubic capacity than on the smaller (3600cc) 911 Turbo's engine, since the difference in torque output between no-boost and full-boost conditions will be less pronounced for the larger engine, so turbo lag is less of an issue.


That´s my understanding as well. Those VTG turbochargers, especially on gasoline engines, are complex and have to endure significant temperatures. Guess that Porsche wants to gain more experience with them first before transferring that technology to the V8 engines.

MHI is not the only manufacturer of titan impellers in turbochargers but might be the first one that ventures out into this field of high-performance gasoline engines. The problem might not even have occurred in development since only certain load conditions and driving scenarios might lead to the above mentioned fatigue of components. It does not even have to occur in a driving scenario with high power output and high engine temperatures but at comparatively modest throttle applications yet changing turbocharger loads or just a high number of cold starts (and therefore temperature changes). These conditions might not have been fully explored during the development stage but experienced during pre- and early-production testing in regular traffic.

As I said before, it would be great to gather some more background information about the choice of MHI turbochargers and the specific issue that has occurred on early-production cars.