Druckdose beim VNT20 drehen... | Posts 16+

'By adding an additional pipe section, the contribution of pressure waves to the engine's drive system will likely be reduced, as the pressure waves from the individual cylinders will dissipate within the additional volume of the pipe.' Translation: The turbo lag will become even more pronounced, something that was already unavoidable due to the switch to the VNT20.


Hi Ulf, hello everyone,

I just randomly found a picture of an Audi 2.5L V6 TDI engine.
So, if I look at this, the distance from the exhaust port to the turbo is 3 times longer than what I had planned (see the picture)!
I think I can now get an adapter welded on without any worries .

Regards,
DJ.

PS: No more engine pictures, please! Thank you again, Mr. Antje!

The exhaust manifold is designed with double walls to minimize heat loss, as the path the exhaust gases take is quite long.

dj1 wrote:

PS: I don't need any more pictures of the engine!

The distance to the spray booth wasn't even enough to fit my hand, and I didn't manage to get any decent pictures. Therefore, also the note about "3, 2, 1".

The exhaust manifolds on V6 engines are double-walled. However, I believe there was a problem with certain production years, where the inner wall of the manifold would fail, potentially damaging the turbos. It might not be absolutely necessary for you.

Why are there two Flexro tubes inside, and whether or not you need one...

Hello everyone,

The adapter piece is finished!
Since I couldn't or didn't want to rotate the turbocharger housing, I devised a solution that allows you to keep the original VNT20 turbocharger while still using it with an original AFN manifold.
I widened the manifold to approximately 39mm.
The surfaces still need to be planed before I can install everything.
The bend in the pipe will make the turbo protrude slightly higher, but that's not a problem because everything needs to be adjusted anyway (exhaust, oil lines, etc.).



Regards,
DJ

Hi,

and does that then fit in the engine compartment?

Best regards, Rainer.

Hi,

and does that then fit in the engine compartment?

Greetings, Rainer

Sure, I've measured everything.
The turbo isn't positioned much further back; it's just sitting higher than it was before.
I will take pictures when he is inside .


Regards,
DJ

Did you also consider providing support for the charger?
Apart from the fact that the weld on the three-hole flange doesn't look particularly reliable (sorry, it might just be my perception), that's probably where the highest stresses will occur. Without any support, the heavy load will likely subject your custom-built intermediate flange to significant oscillating stress in a very short amount of time. What materials did you use?

Hello again to the charging experts,

Please take a look at the two loader photos in...
http://www.polo9n.info/polo-569.html
(scroll down a bit): there's a VNT20 turbocharger installed on a 1.9L TDI engine in a Polo 9N.
According to my observation, the photos show an upward view, and the charging socket is facing towards the rear of the vehicle.
It's clear that the oil pressure line appears to be coming from below, which means the oil drain must be located at the top. Therefore, the turbocharger is mounted upside down compared to the standard turbochargers used in the transverse-mounted 1.9L PD engines.
Can this work, or what problems might arise? Alternatively, is this perhaps the normal installation position for the VNT 20?

(I don't want to install a VNT20 in my Polo, but I'm still interested in it.)

ulf wrote:

It's clear that the oil pressure line appears to be coming from below, which means the oil drain must be located at the top. Therefore, the turbocharger is mounted upside down compared to the standard turbochargers used in the transverse-mounted 1.9L PD engines. Can this work, or what problems might arise? Alternatively, is this perhaps the normal installation position for the VNT 20?

Hi,

If the oil drain isn't positioned exactly at the bottom, you won't enjoy the turbocharger for very long. Estimated lifespan with top-mounted exhaust port: 20,000 km.

One could build an after-run system for the oil that would pump engine oil through the turbo (using an electric oil pump) until it cools down. Quite a complicated story...

Regards,
Jens.

ulf wrote:

Hello again to the charger experts, Is this possibly the standard installation orientation for the VNT 20?

No, definitely not the normal situation. The oil leak is right above mine.

dj1 wrote:

You could now drill a hole with a thread and screw the third screw in there (see picture 4), but will that cause any cracks? I generally don't like drilling into exhaust housings. What do the experts say? Can I cut such a thread into the exhaust housing without any negative consequences?

Hey, I would drill without hesitation; it's just an M5 thread, and there's plenty of material around. However, the hole must be perfectly perpendicular, and the tap must be inserted straight. This is not a job for a hand drill!
A good drill press and a bit of ingenuity when clamping the housing are essential. Also, it's a sinkhole, so don't drill too deep .

Regards,
Jens.

Jens 16syncro wrote:

[If the oil drain is not positioned exactly at the bottom, you will not enjoy the turbo for very long. Estimated lifespan with top-mounted exhaust port: 20,000 km. One could build an after-run system for the oil that would pump engine oil through the turbo (using an electric oil pump) until it cools down. Quite a complicated story...

Hi Jens,

So, you mean he's having problems with the hot oil solidifying after he turns off the heat?

What does it look like in a standard installation? The hot oil is dripping back from the bearing housing into the oil pan, but this doesn't cool the oil film remaining in the bearings either, because no more oil is being pumped in.
From this perspective, the heat issue when the charger is parked shouldn't be any greater if the charger is installed upside down... Or where am I going wrong?

dj1 wrote:

My question: Is it a problem if the exhaust gases have to travel a short distance upwards before reaching the turbo? I imagine it's something like what's shown in my sketch (see attachment). What do you think about it? Please provide suggestions and tips.

Hi DJ,
I think it's safe to mount the turbo a few centimeters away from the exhaust manifold; I would do it that way myself if I ever needed to.

The oil drain hole should point directly downwards. If it doesn't, premature turbocharger damage may occur due to oil carbon buildup. You can read more about it here:
/viewtopic.php?t=12871
I now believe that the turbocharger damage to my car was caused by this issue.

Regards,
Jens.

ulf wrote:

How does it look with a standard installation position? The hot oil is dripping back from the bearing housing into the oil pan, but this doesn't cool the oil film remaining in the bearings either, because no more oil is being pumped in. From this perspective, the heat issue when the charger is parked shouldn't be any greater if the charger is installed upside down... Or where is my flaw in reasoning?

Hi Ulf,

I have to admit, I can't quite figure it out using normal logic either. Your considerations are correct, or we could even go a step further.
Where does the air come from that is necessary for the oil to actually drain from the bearing housing? Without ventilation, nothing would drain. It doesn't come from the supply line, as that is not empty. Could it be from the bearing air of the rotating shaft? If so, the draining would be very slow, as the bearing air space is very small. And by the time everything has drained, it would already be carbonized. Or not?

It is certainly true that in every turbocharger taken from a production vehicle, the drain hole is located almost directly at the bottom (if anyone knows of a counterexample, please report it immediately). There has to be a reason for it.
In addition, I experienced two premature turbocharger failures, where the exhaust port was angled approximately 30 degrees. Therefore, I believe the drill should be located at the bottom.
I cannot provide a precise technical explanation beyond the usual generic statements about coking.

Regards,
Jens.

Jens 16syncro wrote:

It is certainly true that in every turbocharger taken from standard production vehicles, the drain hole is almost exactly at the bottom (If anyone knows of a counterexample, please report it immediately). There must be

some reason for it.
For that, I would prefer the oil to flow back into the oil pan rather than leaking past the (in)seals into the fresh air or... Exhaust pathways.
That will likely be the case (depending on the mileage, it might be slower or faster), if a charger is mounted upside down.
When the oil seeps into the VTG (Variable Turbine Geometry) and evaporates during the next trip, it not only makes the VTG difficult to move due to normal soot buildup, but also adds oil carbon deposits to the problem.

Quote:

Furthermore, I experienced two premature turbocharger failures, where the outlet port was angled approximately 30 degrees. Therefore, I believe the drilling should be located at the bottom.

But those were overheating damage, if I recall correctly? Could excessive LD (loss due to damage) also be caused by VTG (Very Tight Grip) clamps?

Did you also think about providing support for the charger?
Apart from the fact that the weld on the three-hole flange doesn't look particularly reliable (sorry, it might just be my perception), that's probably where the highest stresses will occur. Without any support, the heavy load will likely subject your custom-built intermediate flange to significant oscillating stress in a very short amount of time. What materials did you use?

I'm still considering whether or not to get a brace, but I know some people who drive a VNT20 without a brace and nothing has happened.
Regarding the weld, all I can say is: before it breaks, my studs will break first.
I've attached another picture so you can see it better.

Has anyone ever experienced a situation where the studs sheared off?
I can't imagine that.

Regards,
DJ