thorium

The Acura RDX is said to have a variable geometry turbo charger. Its one of the very first cars to have this, the only other car (I think) that will have this in 2007 is the new Porsche 911 Turbo which features a new variable turbo charger:

FROM: http://www.autoblog.com/2006/03/01/g...che-911-turbo/

Porsche's variable turbine geometry (VTG) setup on the 2007 911 Turbo was developed in close cooperation with Borg Warner Turbo Systems, and is based on technology which has been widely and successfully applied to diesel engines since the early 1990s. It is nearly identical in concept to other turbo manufacturers' variable nozzle/geometry compressors, including a system that was briefly used on a series gasoline production engine in the late 1980s. This application encountered difficulties due to high operating temperatures -- a problem not easily solved with contemporary materials -- and production was stopped after a limited run.

After nearly two decades, aerospace-grade materials have allowed the progression of variable-geometry turbo technology to the point that it can now reliably operate in the higher-temperature environment of turbocharged gasoline engines. Porsche's version of variable turbine geometry in the 2007 911 Turbo incorporates these latest material applications, plus a sophisticated control algorithm. The combination produces the advantages of both small and large turbochargers, generating a much wider plateau of torque and providing quicker response compared to the previous generation 911 Turbo, while providing the reliability of fixed-vane turbochargers.

cmcbruin

Sounds great. Where have you seen that the RDX will have a variable geometry turbo?

If it does, it seems like turbo lag will be a thing of the past.

thorium

I don't know anything about cars, and I don't know anything about Acura's new turbo, so I don't know if turbo lag will be gone, but it should be improved at least.

Acura has stated it will have a variable flow turbocharger. Check out the first video on this page, at about 6 min 40 secs.

http://www.vtec.net/articles/view-ar...icle_id=478706

Transcript (not exact quotes but very close):

Jeff: Since honda has been so resistant to do turbo-charing for so long, are there any breakthroughs you can talk about that make this different, than say, the Mazda CX-7 that has a little bit more horsepower and same displacement. What sets the Honda turbo apart?

Acura Guy: The refinement in our drivetrains is the differentiator. We have a variable flow turbo valve in the actual turbo system itself, that allows for different variations of turbo input into the engine, so its not like an on/off switch where its either on or off, its a very refined system, that carries power all throughout the power band.

Jeff: So does this variable inlet technology... what does it do for boost lag?

Acura Guy: It allows for faster spool up of the turbo system itself, so you can vary the input of the actual turbo charge that you're providing to the engine.... it helps minimize turbo lag.

jz-97-c7

the ford powerstroke v8 and the gm duramax diesels both run variable geometry turbos also.

thorium

Yeah the tech has been around in diesels.

Gasoline engines run hotter temps though so I guess until now nobody has wanted to do one because of reliability

batman

I was watching some show on the speedchannel and this guy had one on his hyabusa. I'm not too smart on this stuff but I remember him saying the turbo would change the boost levels from gear to gear.

kbecker

Audi uses a Borg Warner variable geometry turbo in their new 2.0L FSI engine. This engine made Ward's top 10 best engine list this year and was highly praised for having very little lag. Some of that is probably due to direct injection, though, which the RDX engine will not have.

kbecker

Now I'm not so sure about Audi and their turbo setup. Initially I read this from Wards Auto:

"The 2L mill has a variable-length intake manifold and a superb BorgWarner Turbo Systems variable-turbine turbocharger that, when combined with FSI, all but eliminates turbo lag, just about the last remaining drawback of turbocharging."

I can't find a single corroborating source, though. You'd think that Audi would be hyping that up a bit if it were true, and Porshe would be lying about the 911 being first, too.

Bottom line: I think Wards is wrong and Audi just got a tuned up K03 or the like instead.

Colin

This is from the Acura Press Release:

"This is the first application of forced induction technology in Acura history. The revolutionary i-VTEC Turbo technology uses a variable flow turbocharger, which is exclusive to the RDX"

I hope I'm wrong and we get a variable (vane) geometry turbo. However, somehow, I'm guessing we'll have some kind of variable turbo inlet that pinches down to increase exhaust gas velocity at low RPM, and expands for good flow at high RPM. (think afterburner nozels on a jet fighter)