VNT Turbo - the inside info

[futbus]

We bought some turbos all off cars of less than 5 years old and main dealer returns, but all had issues mainly stuck vanes or damage to the vanes.

The stripdown is fairly straight forward so no point documenting this. Turbo stripped was a good 2011 unit although a fair bit of carbon build up and was sticking. After stripping the unit went into an ultrasonic cleaner to get the most off.

So the main parts of a turbo are divided into 3 parts



The main impeller shaft



Fresh air side



Exhaust side



The vnt has variable vanes



These are controlled by a cam arrangement



These move and control the exhaust gases through the turbo changing the speed of the vane shaft





This is installed into the exhaust side of the turbo



Closer look at what the adjustable vanes look like in the main exhaust side in each position





The control of the adjuster is via a cam through the body to the outside and connected to diaphram control



control for the vanes as seen from the outside of the exhaust side of turbo



New `O` ring installed onto the fresh air side of turbo housing



Fresh air housing installed back on



Diaphram control for the turbo vanes installed



Full turbo now back together and working



Details of the casting number of the turbo thats been rebuilt



If anyone has details that they can add to this thread then feel free to share info.

[..lee..]

be carefull fitting the vnt17 and bigger nozzles. i wasn`t

[syncroandy]

I also R&R'd the VNT15 I used on my AFN build, well worth doing. One thing I'd didn't do was to use a vacuum gauge to adjust the start of actuation of the diaphragm, as I didn't have a suitable gauge. I just set it back to how it was when I took it apart. It had an AR of .33 though most seem to be .46, seems to work just fine though, I get .5bar 'normal' boost, going up to around 1.2bar under heavy load.

There do seem to be quite a few different part numbers for the VNT15 depending on the vehicle. I suspect the actuator and oil inlet/outlets positions may vary, but as I've not had them through my hands I don't know for sure. I expect some variants lend themselves to use (with an adapter) on the JX manifold more than others. It'd be good to hear of combinations that are proven to work. All I can say is the 3b Passat turbo/mani do work, I used a stock VW oil feed and custom return.

Agree with Lee, IMO any non-standard turbo, nozzles etc. should be accompanied with a suitable re-map otherwise running characteristics of the engine will deviate from those designed, with possible unfortunate consequences..