Vgt

[NIXR6]

Hey everyone.

I spent some time researching variable geometry (vgt) turbos today.

I was just wondering wat your opinion of Variable Geometry Turbo chargers on an 6t of f6 motor be and the forseeable gains/losses in performance and further more on a tuned length manifold would it be worth the effort..

Im Curious to know how low you can potentially start developing maximum torque.

If any one is intereseted in this and is well informed please let me know.

[ETM]

VNT turbos have been around for years and do work well but they are not generally available in larger sizes, I know that mercedes sprinter vans have been running them for years with good results but I cannot see them taking over the performance scene anytime in the near future.

How VNT™ Works - Honeywell Turbo Technologies.

[Ricky N]

Variable vein turbo technology has been around for quite a while.

There are plenty of variable vein turbo’s in use from many manufactures. The biggest one I have is a Holset that is a around a 1200hp to 1400hp turbo. They do come bigger though.

The variable vein turbo’s are used primarily on diesel engines. Pretty much every modern turbo diesel car uses a variable vein turbo. From the ZD30 Nissan patrol, Turbo diesel Astra’s, Turbo diesel VW’s through to the turbo diesel Mercedes. If it is a modern car and it is turbo diesel, it most likely has a variable vein turbo.

Variable vein turbo’s are not used in petrol engine by the masses because of the high exhaust temp of a petrol engine. If the same materials where used in petrol engine as the Diesel variable vein turbo’s the turbo veins wood fail. So variable vane turbos for petrol applications need to be made from much more durable materials and require a precise electronic computer control.

This makes them expensive and complicated for aftermarket use. In an aftermarket application ideally the turbo would have to be tuned just like your engine gets tuned. More expense and who would tune it? 99% tuners would have no idea what needs to be done.

There have been a few variable vein turbo’s for petrol applications but they usually fail due to the high exhaust temps of the petrol engine.

In the 80’s Carroll Shelby was involved with Dodge Daytona that they used a variable vein turbo. Reliability issues forced them to go back to a conventional style turbo.

Then in the 90’s Corky Bell’s book Maximum Boost introduced us to the Aerodyne Aerocharger. The Aerodyne Aerocharger is a self oiling, self cooling, duel ball bearing turbo. (No oil lines or water lines neeed. It has its own oil reservoir.)

It is a very different design from most bb turbo’s. Both ball bearings are in front of the compressor wheel. I have never used an Aerodyne Aerocharger but I have poked around inside a broken one. The Aerodyne Aerocharger uses very thin sheet metal for the vains so anything over around 10psi of boost causes the veins to fold over and the turbo fails.

The Aerocharger’s are also very small mainly used for low boost motor bikes and snow mobiles.

BorgWarner started using VTG (their version of variable vein) in the new twin turbo Porsche

911. The variable vein parts are made from very durable materials to cope with the high exhaust temps. The turbo’s are also completely computer controlled via little electric engines that moves the variable vanes.

A few of years ago BorgWarner published a statement saying by 2013 BorgWarner VTG (variable vane turbos) will be common place in the whole automotive industry.

Does this mean petrol engines as well?

Mercedes have turbocharged a few of their new and coming models and I have read they are using 3K / BorgWarner turbos so it will be interesting to see if they are using the VTG turbos.

Cheers,

Ricky.