VNT15 on 1.6 Diesel

[snowbunnyrabbitgtd]

So I have installed a VNT15 onto my CR 1.6   This build has taken me countless hours of research, and talking to many people. In the end I decided that I had so many questions that could, or should have been easily answered, and I felt that I should help those wanting to do the same thing. With all the pictures no longer available its hard to understand and figure everything out right? So I will upload pics as I keep going, and go into best detail that I can for all you!
To begin, there are different styles of VNT turbos, Borg Warner has their own style, which is a pressure actuated VNT. Garrett has the vacuum actuated turbo. The stock VNT15 off of an ALH is the Garrett style turbo charger. Further more, everyone that has posted about the VNT15 seems to have their own idea on how they work, and almost none of them are correct on how they truly work. The VNT turbo charger is essentially a variable A/R turbo. If you don't know what A/R is, i recommend looking up Engineering Explained, and watching all of his stuff on youtube as far as turbos go, and VNT
Now when the VNT15 has absolutely NO VACUUM the vanes are completely open. On other forums and posts I could not get a straight answer. So remember that if you are planning on doing this. 0% Vacuum = vanes open
Open vanes are for high capacity, low velocity, meaning you need to be running in the higher rev range to get your turbo to spool. All that needs to happen to make the turbo spin faster is to apply vacuum on the VNT actuator. about 17inhg will fully close the turbo vanes. The hardest part of this build is the boost controller, how does one have an adjustable vacuum.
People have completely bypassed the VNT actuator by removing it, and replacing everything with a mechanical linkage set up. I said screw that, too much work, and it looks kind of crummy. Some people did it really really well, where as others, it just looked awful. too many moving parts, if one thing fails then boom your engine are turbo could be toast.
Kerma TDI has this part that is sold called the "Dawes Device" which is a manual boost controller for the VNT 15. its about 70 bucks, and its now made by a company called 3BarRacing. I recommend getting that, I will draw later as to why the Dawes Device works, and why it can work really really well.

Most people are in tune with their cars, and can tell when something has gone wrong, and what I like about keeping the turbo stock with the vacuum actuator is I can simply shut it off. All you have to do is run a 12v vacuum pump (They are like 30 bucks on amazon), a switch (if you want a kill switch for the turbo), the Dawes device, and boost line!
Again I'll post more about how everything works this week. If you guys have ANY questions at all, please feel free to ask me
I know a couple people that are running the dawes device, and they say its the next best thing if youre not running an ALH PCM and all the electronic stuff that comes with the original car.

[snowbunnyrabbitgtd]

I also forgot to mention, which its fairly well known, but all COUNTERFLOW vw intake and exhaust manifolds will bolt directly to other vw COUNTERFLOW engines. Gasser or diesel, it doesn't matter. That is how we are able to use a VNT15 on an engine that isn't the famous ALH 1.9TDI. You may want to gasket match the head on the intake side, the exhaust side however will not need that. For those that also don't know, the VNT15 exhaust housing is all the same casting as the exhaust manifold. They are inseparable without cutting to separate the two. The VNT15 may also need to be re-clocked, but don't worry about that too much, its very very VERY easy to do, and takes about 10 minutes to do. Just make sure everything is tight.

[libbydiesel]

The (major) downside to operating the VNT turbo the way you describe is that the vanes are always fully closed unless you are at max boost.  That creates excessive exhaust manifold pressure, hurts engine efficiency, and reduces engine power at any time other than max boost.  Basically you constantly have an engine brake applied.  It will also dramatically over-speed the turbo if you ever pop a boost hose off at higher rpms with potentially catastrophic results.  Just saying.

[fatmobile]

I flipped he internals on the turbo controller so boost controls the vanes instead of vacuum.

[snowbunnyrabbitgtd]

Thats where the dawes device comes into play my guys. The Dawes device allows your turbo to run the standard vacuum regulated system, while using boost to control the vanes. Go check it out on Kerma TDI. There is a ball and spring that gets pushed down relieving the vacuum off of the VNT thus starting to open the  vanes variably depending on boost pressure. This makes for a very good VNT system, so you arent open the vanes just at maximum boost pressure, it keeps the variable in variable nozzle turbo; variable.

[snowbunnyrabbitgtd]

also, the vanes with the dawes device aren't fully closed until max boost. Only repeating myself to make it crystal clear.

[libbydiesel]

I understand how the 'Dawe's device' and how the VNT turbo vanes function.

also, the vanes with the dawes device aren't fully closed until max boost. Only repeating myself to make it crystal clear.

You're making even less sense with that comment.  Vanes OPEN reduces exhaust velocity and lowers boost pressure.  Vanes CLOSED increases exhaust velocity at the turbine and consequently increases boost and exhaust manifold pressure.  If the vanes were not fully closed until max boost, then boost would build very slowly off idle and then spike uncontrollably and without any max boost regulation at all.

Here's a quote from Kerma's description:

Later models, referred to as A4-chassis (all New Beetles, and Golf/Jetta TDI after '99.5) have a vacuum-operated turbo controller. On these, vacuum is applied all the time (e.g. at idle) and at higher boost pressure, the N75 solenoid valve (or the Dawes) breaks the vacuum so as to open up the vanes in the VNT mechanism.

Although I don't really like repeating myself, I feel this is important enough to do so.  Keeping the vanes closed all the time except for max boost (as is clearly stated in Kerma's description) is a mistake.  It is not how any car manufacturer, including VW, operates the VNT turbos because it is inefficient and dangerous.  Keeping the vanes closed except when reaching max boost causes excessive exhaust manifold pressure, acts like an engine brake, hurts engine efficiency, generally over-speeds the turbo, and will dangerously over-speed the turbo if you ever lose a boost connection. 

I don't really want to get into an argument about it and my comments are simply an attempt to potentially help other folks from doing similarly and causing themselves undo issues.  I don't actually care what you do with your car or to whether or not you agree with my assessment.  On that note, I'll exit this conversation.  Good luck with it.     

[fatmobile]

Yep, from my experience the vanes need to open up quite a bit by half throttle.
Maybe half way.
 Then open gradually from there.
 With the VNt-15 you can really feel excessive boost slowing you down when you take off.
I think that's what's good about a vaned turbo.
 A wastegate doesn't really reduce back pressure as much. Exhaust still has to get pushed through the small gate.
 I had my 15 start rubbing the housing. I was able to mechanically open the vanes all the way up and make it home without the turbo spinning/grinding.
 The exhaust flows straight through it so smoothly when the vanes are opened. Unrestricted. Less back pressure.
Besides when the vanes open you can hear the engine roar.

[snowbunnyrabbitgtd]

I had stated something wrong early, and thats my fault. Inserting foot in mouth right now
I had stated in my "making things crystal clear" comment that the vanes arent fully closed, yadyada
I firmly believe the fine tuning the the manual boost controller will make for a very well working engine and VNT. With the direct quote from Kerma TDI, they talk about the electronic VNT controller breaking vacuum at full boost. Thats exactly what we are doing with the manual boost controller is it not? Build full boost, break the vacuum seal on the Dawes device, and from there have the nozzles change from high velocity low capacity to low velocity high capacity due to the change in our RPMs
Personally I have full faith in this system and have seen it used very well an reliably. I feel the biggest part is incorrect installation, or cutting corners can cause issues. Another thing I did talk about is putting in the kill switch for a 12v vacuum pump in case if something did happen to something within the turbo boost system, may it be blowing off a CAC tube, or something else. At that point you can flip the switch to the off position killing the 12v vacuum pump thus opening the turbo vanes and essentially getting a "Limp mode"
I currently have the 12v pump and switch that I am using on my system for that very reason. Just in case if anything were to happen. Another note, I mean cmon, its a VNT
Who doesn't want to hear those awesome sounds and have that turbo spool almost on demand??? You just have to engineer the system well for you.

Back to the demon at hand in an attempt to convince more people to do this, personally I feel its nothing to be afraid of. You may have a run for your money getting all the fittings you need. I bought a t3/t4 turbo feed and return line kit, and also purchased -4AN to 1/8" NPT fitting so the turbo has the proper fitting for the feed
Also bought a fitting for the oil pan, and drilled an appropriate sized hole for it so I could run  1/2 hose from the turbo drain fitting. as far as fittings go, I'm still undergoing this full process of turbocharging the vehicle and will most likely be using the t3 feed adapter, boring it out and using that as the new turbo drain fitting. Not quite sure yet on that. I may ask some friends at the machine shops if they can make me a new one that will accept 1/2 hose.
All in all though, EMPs i believe aren't something to really worry about. If you think about it people are running smaller turbos without EMP gauges, and they are fine. EMP will also be released when the vacuum seal is broken on the boost controller and the vanes start to open up. The biggest thing to truly worry about in my opinion, even as a professional automotive technician, is the EGTs.
Anyway, I have gone off on a tangent, I shall post some pictures this weekend

[fatmobile]

Yep, the turbo should be tuned so the EGTs stay in a good area.
Lower when cruising,...about 800 F when boost is 8psi
 

 and around 1200F when floored and boost is 15 psi and up to 18.
 That'll help keep the VNT vanes from sticking.

 I really like the VNT-15 on a 1.6.
 Spools up early, sounds great.. and I don't need more than 15 psi boost.

[snowbunnyrabbitgtd]

thanks for you input fatmobile, I'm pretty excited, I've got headstuds in my 1.6 right now and I'm planning on max boost of 20psi
Sadly today I couldn't get any pictures, but tomorrow I'll be able to get a handful! Loving the progress of this, hoping others will like it as well. I'm new to posting on these forums, and even searching on them haha, I normally just clicked on what google pulled up when I had a question lmao!

[carrizog60]

i have a passat 1.9d (1y)with a vnt 2052.
i only replaced the vaccum can for a boost one. no linkages,no electronic devices(if i wanted them i would go tdi)
i choose the one that starts to open with the least boost pressure(if i remember is from a garret t2) and added a  outside spring mounted on a threaded rod so i can set the tension and by that way control the speed that the rod moves/how boost behaves.

i choosed the bigger 2052 because i didnt want to have boost too early(turbo is trying to make boost then mantains it using a pressure can remember) and still had to adjust the starting point to avoid choking the engine/boost creeping too fast.

this way for me is the simplest,the more sound/comfort friendly(only is loud when i hammer it,cruising is ok even with a 60mm straigh pipe), and easy to tune.
without external spring i peaked at 1.1bar and had a somewhat abrupt transition but now is a way more soft transition(only abrupt if i go wot from low rpm) and i can dial boost( i have now 1.5bar,was running 1.8 but wanted to give it a rest lol)

[fatmobile]

 What's 2052?
 What does it come off of?

[carrizog60]

Vnt2052 or GT2052 came from the vw/audi 2.5 tdi.
Usually in europe was found on the audi allroad model.