Sounds interesting stuff T:

Why will you not use a N75 map to control the vanes, I don't get that bit? The A4 supports an N75 map doesn't it?

 

i will use the n75, thats what i said, the wastegate solenoid is on the same pin on the ecu.. so n75 is plug and play.

every where i have read about vnt on a t4 they saying about having to map the egr to control it... think there talking bullll.

 

I'll briefly explain how the ECU controls the vnt and why all the bits....
Ok the vacuum ball and one way valve first. The vacuum supply MUST be consistent and although changes in its suction pressure will be compensated for by the ECU, it cannot compensate for sudden changes like stamping on the brake peddle several times. The "ball" holds a temporary supply of vacuum for such instances and the one way valve stops the brake servo from depleting it.

Onto the turbo then, if you supply full "suck" to the VNT mechanism, the veins inside the turbo will direct the exhaust gasses directly at the hot or exhaust turbine and it will give maximum boost. If this situation were to remain, the turbo would likely reach a boost level much higher than it can mechanically sustain and it would destroy itself. The ECU then, will reduce the amount and try to keep it to a preset map programmed within the ECU itself. The N75 valve works on a fully open or fully shut basis but against a spring and the ECU will actually open and shut the N75 valve hundreds of times per second but it will change the amount of open times or closed times within this switching. This is called "Pulse Width Modulation" and the average of the open/shut times will give, effectively a fully variable control of the amount of vacuum supplied to the VNT control capsule on the turbo. So that the ECU knows how much to change the signal to the N75, there is a MAP sensor fitted to the pressure side of the turbo. This Manifold Absolute Pressure sensor can be replaced if you wish to use very high boost pressures.
To prevent dirt getting sucked into the vacuum pump, the "atmospheric" pipe of the N75 is routed either to the air filter box or a small filter can be fitted to it...T:

 

Oh and one further top tip. Use Ebay.de, you can login using your UK details and make use of Google translate especially when communicating with the German vendors and asking if they can post to the UK etc. They respond better if you make the effort.
Here are a couple of examples of AXG manifold and the correct spelling so you can copy and paste...

http://www.ebay.co.uk/itm/111918314222?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

http://www.ebay.co.uk/itm/111918315331?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

.....anything you save in your watch list on Ebay.de will automatically appear in your UK watch list by the way!

 

Forgot the turbo!

http://www.ebay.co.uk/itm/151743138874?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

Some good info for others planning on doing the same,

my vans in my unit this week, so ill test the ecu and n75 on vagcom, post a little video of it moving the vanes on the vnt.

the manifold ive got is a slightly different flange so ill need to fack about with that to get the turbo on.

also, the downpipe from a AHY should fit this conversion and make it a complete OEM install.

 

This is very interesting!!! What are the differences between the gt2052v and the s? Was the A4 ecu you used from a 110 afn engine car?
Will be following this with interest!

 

Yes the ecu is from a A4 AFN 110. Look at the ecu number on your van, the letters at the end denote the tune that is on that ecu. Most of the tdi ecu's are the same from within the same year bracket, they just have a different software/tune on them.

Some will be socketed, some wont be , this will be a different part number as well as different letters. But the ecu will function the same.

There are many versions of any turbo , different trim specs ect.. different vnt mechs, different actuation. But all may still come under a "gt2052v" for example.

The S is the newwer of the gt2052v so its ment to have a little higher spec that the rest. Although without looking i cant tell you where this lies atm.

Its allso worth noting that a gt2052v will need to be clocked , by this i mean the center core rotated around the exhaust housing to put the oil drain in the correct place.

This is because of the way it sits on the v6 engine, in the a4 2.5tdi

Some gt2052v turbo dont come with enough holes in the housing to do this . But some do .

 

Really good thread (for some early morning reading) .............. got no technical input to add, as I have not done this myself.

One thing I would say over years and years of dealing with Germany and German ebay sellers is MOST HATE GOOGLE TRANSLATE!

I have a company who will buy parts for me if the seller WILL NOT ship abroad (and many won't). Once they receive the items and confirm all is well, they calculate DHL at cost and add the percentage we have agreed. I transfer the funds, and 2 or at worst 3 days later the parts are in my hands.

It's worth trying to establish some good contacts, not just for an exercise like this, but generally, as parts become that much harder to get hold of. I'm in my 25th year of T4 ownership and it's not like the old days when everything was either 'off the shelf', or overnight from VW

 

Great work, I've been looking into doing this for a while, but was put off by changing the ECU. Mines been chipped by Wayne at Chipwizards, running 216 injectors, l200 cooler ppt exhaust, puts out 140 bhp now, but I've fancied changing the turbo and have been limited by not being able to go down the VNT route. hopefully this should be straightforward enough, as I have a AHY manifold, so just need the rest of the parts on the list and were off.

 

Isn't the gt2052s a wastegated turbo?

 

It is yes.

 

Thought as much. Thought didn't read it and assumed you were referencing the gt2052s as opposed to the p/n with an 'S' suffix. That'll teach me to skim read!

Does anyone happen to know if the 'S' suffixed VNT turbo can be clocked without drilling? I have one, but not to hand and need to to be a bottom mount turbo as opposed to top (need to level out the engine in order to attempt to fit the 02M gearbox).

If not, not to worry. I'll give it a look when I can next get out to my box of parts... If I can separate the turbine from the housing.

 

haha !

ive got one just sat there, ive yet to touch it ! busy week with me E30 (show session is coming)

Well that's £150 down the toilet:

how did you do that http://www.vwt4forum.co.uk/images/icons/jaw-dropping.gif

 

Well that's £150 down the toilet:

 

The hot side wouldn't budge using brute force, so being as impatient as I am; instead if looking for a tire to heat the thing up, I tried the spacers between the bolts as the cold side technique.

Never had a problem with it on WG turbos or the the GT18V I used to have, so I thought 'why not'?

Maybe I should look for a T25 turbine flanged one with the CHRA already in the opposite orientation...

 

you just gotta give it a good tap while holding it in your hand i found lol.

 

So ...

after a wiring loom fault (almost burnt the van out) pesky 109 relay, stupid wiring loom covers and a few massive water leaks.

The injectors are in, feels much better down low but you can feel the air restriction up top past 3k.

got to sot out map sensor boss, then plug the 151bhp ecu in and test the n75 for vnt

 

Haven't done map sensor yet (needs a 4pin 2.5bar as i've removed the internal one from this ecu i have)

but.... we have some VNT action.

as said before you don't need any modifications to the loom or the software to do this.. just plug a 151bhp ecu in change to an N75 on the same cable as your wastegate solenoid and it will work.

 

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