variable turbine geometry

[bony]

has anyone heard of the variable turbine geometry thats on the porsche 911 turbo? its pretty good i rekn.. kinda like vtec buh on the turbo... i wna kno if anyones got plans of chukin these on there cars instead of big laggy turbos...

heres a link to educate urselves

http://www.autozine.org/technical_school/engine/tech_engine_3.htm

[Babalouie]

Not knocking the technology (or you for that matter) :) but actually truck turbos have had this technology since the early 80's. This might shock you, but Honda released a 2.0L V6 turbo with a variable vane turbo in the late 80's but it was only available in Japan.

It just so happens that I had a 1989 issue of Car Magazine on my desk with the article in it. I'll scan the article and host it up tomorrow.

It's sort of funny, but a lot of the Porsche innovations aren't their own inventions at all. Tiptronic gearboxes are usually thought of as a Porsche design but for years Porsche paid royalties to Mitsubishi for using it.

[scathing]

"VTEC on a turbo".....Christ. There's so much I could say right now, but I'll be polite and say nothing.

Its actually the opposite of VTEC. Instead of giving you a lumpy power delivery where you've got nothing down low and then a sudden rush up top, it smooths out the boost. By changing the geometry of the turbine, it allows it to spool up faster and boost from lower in the rev range. Its basically an anti-lag system.

For a nice flash animation on how it works, visit here (http://www.porsche.com/all/masterwerk/germany.aspx).

Choose "DSL"
Skip the intro
Click "Opus 911"
Under Erste Szene click "Variable Turbinegeometrie (VTG)"


Porsche asserts that they're the first company to release a variable turbine turbo for a petrol engine, but given how the Japanese don't "do" diesel I can only assume that the Honda mentioned above is petrol.

Variable vane turbos have been around on diesel engines for years, but Porsche (and quite a few other companies) say that its been impossible to build a reliable variable vane system for a petrol engine due to the higher exhaust temps, which damages the actuators.

As for who's got plans to fit it in their car, I'm going to guess "no-one" at the moment. There aren't any off-the-shelf aftermarket variable vane turbos out there for petrol engines, which means you'd have to source them off another car. Which means it'll be old and / or expensive.

And then you'd need some kind of controller to control the actuators, which would probably need to be very tight with your ECU since its load dependent and not just RPM dependent. With no OEM ECU having this kind of functionality, it means you'll probably need to go to a custom-made controller with a race-style ECU that lets the controller pull that data out of telemetry to make its adjustments.

[brasher]

The first production car to use these turbos was the limited-production 1989 Shelby CSX-VNT, equipped with a 2.2L petrol engine. The Shelby CSX-VNT utilised a turbo from Garrett, called the VNT-25 because it uses the same compressor and shaft as the more common Garrett T-25.

[Babalouie]

Porsche asserts that they're the first company to release a variable turbine turbo for a petrol engine, but given how the Japanese don't "do" diesel I can only assume that the Honda mentioned above is petrol.


Yup, it's a 2.0L V6 petrol Legend, 180ps.

[Senor_2]

Well said scathing.

Here's the Aussie link to the Porsche site, my German isn't upto scratch :)

http://www.porsche.com/all/masterwerk/australia.aspx