Anyone Make a Variable-Vane Turbo?

They were supposed to be the best of best worlds years ago, acting like a small turbo at low RPM to eliminate lag and acting like a large turbo at mid-high RPM. So what happened, why aren't all manufacturers making them?

The Fed said:

They were supposed to be the best of best worlds years ago, acting like a small turbo at low RPM to eliminate lag and acting like a large turbo at mid-high RPM. So what happened, why aren't all manufacturers making them?

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Maybe twin scroll technology made it obsolete? Not sure.

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TecklenburgVW said:

Maybe twin scroll technology made it obsolete? Not sure.

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Certainly less complicated but I don't think it's as effective.

Variable vane turbos are used on Diesel engines (predominantly) to provide exactly what the OP described small turbo like fast spool at low rpm and then bigger turbo like flow at higher rpm.

The reason they are common on diesel vehicles and not petrol is due to the combustion/exhaust gas temperatures.

EGT's on a diesel are significantly lower on diesel engines. There are issues (technical and material) with maintaining functionality and reliability of variable vane turbos on petrol engines. They do exist but only on a very limited number of vehicles and these are $$$.

I think Porsche are actually one manufacturer that does or at least did use them.


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Variable vane turbos do not run a BOV. It uses its built in architecture to bleed excess boost off. You can over boost an engine during shifts or rapid deceleration. My truck has one and I can reproduce a turbo "fart" manipulating the throttle. They also introduce turbo lag due to the response time adjusting and spooling back up, and their size is massive in comparison. My diesel runs 1100deg at the turbo inlet with a load or heavy acceleration so I'm not sure if temps have anything to do with it.

https://en.m.wikipedia.org/wiki/Variable-geometry_turbocharger





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rscott4563 said:

https://en.m.wikipedia.org/wiki/Variable-geometry_turbocharger

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learned something new today. Awesome. Thank you.

If I recall correctly at least some variation of the turbo 4 boxer engine in the new 718 cayman runs a variable vane turbo.