Fred wrote:Not like you to be cynical Alex
Have you heard of Inconel? It's used on both. EGT's aren't all that much different. (yes, I know you mean the VGT aspect)
not cynical at all, just prudent

from what i read, production gasoline powered cars don't get VGT turbos precisely for the reason of high EGTs. Porsche recently released theirs that is full of exotic materials (=very expensive) to make it somewhat reliable i imagine.
As we both know, diesels operate at much higher compression (= lower EGTs) as well as significantly above the stoich (= again lower EGTs + no trail-burning as all the fuel gets to burn inside the chamber and not in the manifold), so it makes sense that VGTs don't stand the gas engines for very long.
... but, it may work with some amount of water injection
but, of course, i have no practical experience, just the theory and the stuff i read

, so i may very well be wrong (and i would be glad if i am)
EDIT: I'd take vacuum-activated any day over the elec-motor'ed one. I wonder what kind of vacuum does this thing needs? Does it need a standalone vacuum compressor? (or do you call it uncompressor?

) Or does it use the boost that the coldside generates?
If i were to design that thing, i'd make it differential this way: no pressure on actuator = vanes become tight, then there would be a solenoid valve(s) which would control the amount of boost entering the actuator (to control the whole VGT operation). As boost is fed into the actuator, it will expand the vanes.
sounds good?