Quote:
Originally Posted by Dimman
This thing is a Garrett VNTxx. My co-worker's TDI threw a rod at only 18x,xxx kms and he said something about replacing his turbo with a bigger one.
I heard "VNT" and offered him $50 for the old one, wanting to see what a Garrett variable geometry system was/how it worked. Didn't know the damned thing was attached to the manifold...
My understanding is that Garrett's is only a single big vane and is the least efficient (lots of turbulence) of the variable geometry setups.
Second best I've heard is the Mitsubishi which is similar but two vanes that open sequentially and 'backwards' compared to Garrett's VNT. Supposed to be very efficient and very reliable. Is this on USDM Evos? It is apparently on certain JDM models.
Porsche's multi-vane is supposed to be the best performing.
The twin-scroll thing puzzles me as to why it is even a buzz-word. My understanding is that it is just a twin-entry divided turbine, the same as Toyota was using with the CT26 ~25 years ago, or am I missing something?
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modern diesels mainly use multiple vanes. afaik nobody except porsche use variable vanes in gas turbos. not because of a new design, but the proprietary materials/construction of the vanes, which can survive the temps.
the honorable mention, in recent memory, goes to the Acura RDX K23 which used a variable turbine housing, but not variable vanes a la porsche.
as for twin scroll, yeah thats nothing new as well. but companies like BMW try to sell it like it is. they went from twin turbo N54 to the "twin power" N55 single twin scroll turbo.