allroad V6 TDI slow build

**gldgti** · 15-09-2015, 09:18 PM

Yeah man! Weekend turbo swap coming up!

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**gldgti** · 23-09-2015, 08:33 PM

Split a boost hose coming home on the weekend. I used an old hose from my mk3 when I put the car all back together a couple of weeks ago. Turns out that wasn't a great idea.
Replaced tonight with silicon and stainless for win

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**gldgti** · 08-12-2015, 08:17 PM

...and its in!

I have been just driving the car basically stock since I rebuilt the heads, as after i sent the injectors for cleaning, they came back with the number 3 injector (which has a needle lift sensor to tell the ecu about the timing) that didnt work anymore.

Yesterday I finally got around to fitting a working second hand replacement courtesy eBay Italy, and while I had half the engine apart, decided to swap in the BV50 K04 in place of the GT2056

So yeah - turbo swap is done!

Its faster than stock for sure. I have the vane adjustment pretty conservative at the moment, but it spool about the same as the stock turbo. However, the midrange response is much faster, and it pulls much harder at higher revs. I guess that's down to a whole newer generation VNT going in there - its larger, flows more, but spools better.

I had a pantsmessing moment after the first drive, which I stupidly executed without a boost measurement device. It didn't run quite right, and I realise now thats because it must have been boosting way too hard.... but not as hard as I thought when I saw the actuator position at idle, (which is fully closed, maximum boost setting) which for about half an hour convinced me that it was all backwards or something, and that I'd majorly stuffed it. in the end, I have learned that the ECU asks for fully closed vanes at idle, so that boost builds as quickly as possible off idle - its also much quieter that way, as with vanes fully open, there is a way more direct path through the turbine and it makes a lot more noise.

Anyway, after that first drive, I adjusted the mechanism back a lot, so that it literally feels (when you have the car idling with the N75 connected to the actuator, and you pull on the actuator arm with your hand) like the stock one. The way I had it first was probably a bit "light" i.e. when the ecu asked for more open, i dont think it would open quickly, or far enough. This resulted in too much boooooost. Lucky it was a short and tentative drive I went on.

after adjustment, I have it in a spot where it doesnt close all the way to the stop - so in theory I could see some extra response with careful adjustment. Max boost is about 20psi, which is basically pretty much as before, so the ecu is coping with the actuator mechanism OK. I havent seen anything much in the way of spikes.

Regardless, 20psi is getting close to 2.5 Bar absolute, so it might be time to go a larger range MAP sensor.

Cant wait for this to be tuned. Its going to be good!

**Greg Roles** · 08-12-2015, 09:05 PM

Nice to see you still messing around too. Reminds me of the time I messed with my first turbo, and just turned the wastegate arm " a few turns". Sure boosted amazingly well about three times, then I learnt all about the turbo rebuild industry.

Glad your turbo survived !

**gldgti** · 10-12-2015, 08:45 PM

Yes indeed.

Progress on previous post - I've since wound in the actuator arm 2 full turns (1.6mm) and its made a huge difference. Its now a lot more like I thought it should be - much more responsive and quieter too. Boost comes on much much faster than stock.

Basically I have just wound it in 1 turn each day before I leave work, then drive home and keep an eye on the boost. I'm still in the realm of actuator function where the boost isn't running away at high rpm - i.e. the ecu is capable of keeping boost in check under high load - so there might even be another turn in it yet. We'll see.

I'm just chuffed that its working so well. I've got more power, better response, and all with a hardware only change

.

The best description I could probably give is that the car has gone from feeling pretty "old school" diesel, with noise and whine and lag, to rather new school, with quick response and less noise.

I can definitely see why this size turbo is the daddy for the 4 cylinder diesels.

Also considering doing the boostvalve type mod, so that it wont be possible to have boost spikes or overboost. I'm thinking that will let me tune it right to the limit so I get maximum spool without the obvious dangers.

**anthony--t** · 10-12-2015, 10:34 PM

Sounds like I have to come visit you soon for a drive!

**Greg Roles** · 16-12-2015, 07:45 AM

Originally Posted by gldgti

Yes indeed.

Progress on previous post - I've since wound in the actuator arm 2 full turns (1.6mm) and its made a huge difference. Its now a lot more like I thought it should be - much more responsive and quieter too. Boost comes on much much faster than stock.

Basically I have just wound it in 1 turn each day before I leave work, then drive home and keep an eye on the boost. I'm still in the realm of actuator function where the boost isn't running away at high rpm - i.e. the ecu is capable of keeping boost in check under high load - so there might even be another turn in it yet. We'll see.

I'm just chuffed that its working so well. I've got more power, better response, and all with a hardware only change

.

The best description I could probably give is that the car has gone from feeling pretty "old school" diesel, with noise and whine and lag, to rather new school, with quick response and less noise.

I can definitely see why this size turbo is the daddy for the 4 cylinder diesels.

Also considering doing the boostvalve type mod, so that it wont be possible to have boost spikes or overboost. I'm thinking that will let me tune it right to the limit so I get maximum spool without the obvious dangers.

I agree a BOV is the key, would let you tune it a "bit beyond" and let the valve sort the excess. Plus it would then sound fooly sick bro.