Variable Area Turbine Nozzles
 

Is anyone here familiar with VATN's, or more generally called variable area turbine nozzles? Basically, the hot side incorporates vanes that open and close, depending on the the speed of the turbine. When exhaust gas is at its highest, the vanes are closed. When the vanes are fully opened, exhaust gas velocity is at its lowest, therefore backpressure is also at its lowest. Backpressure, of course, is the bane of all turbochargers. From what I have heard, VATN turbochargers offer the lowest backpressure and best response at all levels of the powerband. However, I am curious how the vane actuation works. Garrett has its own version, called the VNT. They claim it works through some sort of vacuum actuation on the hot side. Here's a link.

http://www.egarrett.com/technology/t...&l2id=2&l3id=3

Does anyone here know how the Aerocharger works? I can't seem to get access to their webpage.

Also, does anyone think that a variable nozzle turbine would work best with the RX-8? Since the turbine A/R changes with the turbine shaft speed, this type of turbocharger, I believe it would work best at all levels of the powerband. Unfortunately, I suspect the actuation of the vanes might limit the VATN's ability. I'm not sure. Nevertheless, the VATN has the ability to maximize the RX-8's average power gain by at least 30% over stock, in not more. Time for questions :).

Is VATN turbocharger sizing an issue? Are sizes limited for these types of turbochargers? Lastly, are there any other limitations for VATN's? The only two I can think of are size limitations (maybe), and how to properly actuate the vanes. I will have to do some more research on this :).

Also, what do you guys think about combining an axial-flow compressor and a radial compressor, in that order? Oh the possibilities :rolleyes:.

Unfortunately, my only experience with a VATN turbo is no a good one.

The original turbo I installed on my Miata was an Aerodyne - the company with the original patent on the device. They made the VATN that Corky Bell shows in his book "Maximum Boost".
It was really cool - instant spool-up and full boost across the whole RPM range.
Unfortunately, is was not very durable. It spat out its bearings after about 5,000 miles of relatively low boost operation.
I sent it back for a rebuild and had it calibrated for a higher boost level. It then gave up the ghost again after another 5,000 miles. When I attempted to get it rebuilt again, I found that Aerodyne had gone out of business.
]
So, I threw it in the trash and got a T3/T4 and welded up a new manifold and downpipe.

I would believe that Garrett would make a great product. The VATN idea is great, though probably not necessary since regular turbo technology has progressed so well that the performance gap would be pretty small.

Indeed. I am always open to new technology. Are VANT's boost-limited? The vanes, IMO, seem to be a limiting factor in how much boost the turbo can produce. The technology is not new, but I believe it is widely ignored in the aftermarket circuit. The reason must come from the fact there are so many turbocharger options, that finding the right one can be quick. I mean, I don't plan on dumping any money immediately into a VANT that may or may not reach my expectations. Thank you for your opinion/experience Jeff :).

The Aerodyne VATN had an integral boost control device that actuated the turbine pitch controller. It was modulated via a bleed orifice that was calibrated for different boost levels at the factory.
The turbo acted like two seperate turbos with regard to the flow/efficiency map, but it still had its best efficiency range, boost threshold and surge limit like a regular turbo.

They are especially good for engines with a small displacement and a large RPM range. They were specifically well suited for snowmobiles and motorcycles.

Can VATN turbochargers be improved upon? I absolutely love the benefits of VATN's, but from what you said, there were some durability problems. Why did your bearings fail?

You make a point about the necessity of VATN's. Since Corky Bell wrote about these in 1997, turbochargers have seen much progress. If these turbos were reliable, we might be able to see more of them in passenger cars. In fact, I believe these exist in some. Europe perhaps? I can't remember; "Family Guy" is on.

The Ford powerstroke diesel trucks have variable turbine area turbos on them from the factory.

Diesel engines are a good application for a VATN. They don't have as wide and RPM band and the exhaust flow is high.

Reopening this thread up...

With all these turbo kits getting pumped out... I'd like to see somebody come up with one that utilized a VTN turbo...

heres the website about the garrett one..

http://www.honeywell.com/sites/ts/tt...2155701757.htm

To me.. it looks like the best solution as it has quick spool up and good charge power at the top end.... no need for wastegate either because of the way the vanes work...

the high rpm of the rotary makes this turbo seem like the right choice... anybody figure out more about this thing? or know where to get it? maybe i'll have my own custom turbo built sometime in the future

the other part i find interestign is that Honeywell owns Garret? damn that company has a hand in everything i swear.

I just found out recently that Honeywell owns Fram... I was shocked.

is this goodnews or not?

thats what im saying- they own all sorts of stuff- creapy.

i noticed that they list the 1.6l diesel Mazda3 as having one of their turbos. GT1544V which is one of the VNT models

I don't know if I'd admit that if I were them!

that list is so underwhelming.... its like power of n/a cars...

VANT turbos have a crummy reliability record in automobiles.

Caveat emptor!