Turbocharger Optimization: Worth the Risk?

I found a company online that offers an optimization service for the Garrett GT1749VB turbocharger. This optimization involves coating the inner surface of the compressor housing with a special carbon layer. This causes the compressor wheel to make contact with the housing or the coating. The coating is worn away during the initial operation of the turbocharger. This reduces the clearance in the operating state to almost zero, which should significantly increase efficiency. The wear of the layer during initial operation is supposed to occur without causing any damage to the wheel. Next, the exhaust manifold is opened and smoothed to minimize flow losses, which should allow the turbine to reach its operating speed sooner. For those who are unsure whether the variable turbine geometry (VTG) is properly adjusted, a final adjustment is performed on a flow bench (by a partner company).
What do you think about this? Do you find it useful? It sounds logical and makes sense. However, I'm wondering what happens if the clearance isn't 100%. Since this optimization aims to minimize manufacturing tolerances, it could potentially lead to stress on the housing.
I'm looking forward to hearing your opinions.

We used to do it like this:

We machined the screwed-on housing on the exhaust side on a lathe to achieve the minimum possible clearance (distance to the impeller).
As a result, the turbocharger spooled up much earlier (because less exhaust gas could pass along the turbine wheel).

I would definitely do this again!

I have to mention that I also had the turbocharger replaced and rebalanced at the same time.

Which company did you use for this? Do you have a link (via private message) or a phone number? How much did it cost you (including the new battery)?

Zak1976 wrote:

In this optimization, the interior of the compressor housing is coated with a special carbon layer. This causes the compressor impeller to come into contact with the housing or the coating. The coating is worn away during the initial operation of the charger.

So, uh... if the compressor impeller is in contact with the housing, it is blocked for me.
It seems very questionable whether the turbine, even when running at full speed, will be able to generate the necessary "free-running torque."

And if that were to happen, the wear particles from the coating and/or the compressor wheel would be blown through the intake manifold, engine, turbine, and catalytic converter by the air (or, depending on the particle size, would remain trapped in the catalytic converter) -> truly a brilliant idea.
It kind of feels like an April Fool's joke...

Seals that wear out are not uncommon in turbomachinery. For example, the fan blades (the largest) in the et-series engines of passenger aircraft are partially sealed with a material similar to Prestolith because they tend to elongate during operation, and without this sealing, they would otherwise come into contact with their housing.
Due to the floating storage, the amount of material being moved by the excavator will likely become as large as the amount being stored. Therefore, ball bearings would be ideal for such an operation.
Contact or short circuits will likely only occur during startup.

christians wrote:

Worn seals are not uncommon in turbomachinery. For example, the fan blades (the largest) in the et-engines of passenger aircraft.

Hi Christian,

What are et-engines?
If these are the actual power sources, they must be able to digest a certain amount of birds without failing.
A few tiny particles of sealant likely weigh less in a rotary engine than in a piston engine, where moving parts slide against each other with tolerances of 1/100 mm.

Besides that, I'm quite pleased with my KKK turbocharger in my Polo, which doesn't have any noticeable radial shaft play (ball bearing mounting?).
This alone should significantly reduce the inevitable bearing clearances compared to Garrett turbochargers with "wobbling shaft" (oil film bearing) designs.

Hello everyone,

I think you guys are talking about two different things.
Zak is talking about the reduction in flow on the compressor side, while Fricki is referring to the turbine side. In my opinion, these should be evaluated separately.
"Since the axial clearance is relatively small and depends only on the pressure difference between the compressor and turbine sides, in addition to the tolerances, reducing the axial clearance on the compressor side can relatively safely increase the compressor's efficiency, as the production tolerances are quite generous in this area. The question is what impact this has. It undoubtedly has a positive effect on fuel consumption, but in practice, in the vehicle, this will not lead to measurable improvements in fuel consumption or a noticeably better response, i.e., boost pressure build-up. You simply get the feeling of having an optimal compressor. I know little about the coating and the associated risks. However, there are carbon-based coatings for zero-clearance tolerances in engine manufacturing, but whether the wear is really supposed to be caused by the engine itself? I think they probably mean the break-in period refers to testing on a dynamometer – then it would make sense."

The operation of the guide vanes on the turbine side is a completely different matter. Due to the well-known problems with the guide vanes, jamming must be avoided at all costs, meaning that thermal distortions, material aging, and coking, along with all manufacturing tolerances, must ensure the flawless operation of the adjustment mechanism throughout its entire lifespan. This results in: a significant amount of clearance.
Even this isn't quite enough for the series, so many of us have experienced it firsthand with our own turbines. (Now even my ALH; I measured it for the first time this weekend and saw overshoot peaks of 500 mbar followed by undershoot of 350 mbar – and as a bonus, an HFM that keeps the exhaust gases nicely contained in the smoke filter – great – it's almost like I didn't have anything better to do).
Therefore, a blade configuration tailored to the individual turbine has great potential in terms of responsiveness, i.e., pressure build-up and flow rate (passing through the smoke chamber), as well as fuel consumption. I had the opportunity to test such a turbine in comparison to a standard turbine. The result was surprisingly good. However, it's important to be aware that this is only a limited benefit, as there's a constant conflict between durability and performance.

@Zak, could you please post contact information for that company? Thanks.

bafische wrote:

Thermal distortions, material aging, and coking must, along with all manufacturing tolerances, ensure flawless operation of the adjustment device throughout its entire lifespan. This results in: A tremendous amount of play. Therefore, a blade configuration tailored to the individual turbine has great potential in terms of responsiveness, meaning pressure build-up and flow build-up (passing through the smoke KF), as well as fuel consumption. I personally had the opportunity to test such a turbine in comparison to a standard turbine. The result was surprisingly good.

Hello Bavarian.

How and at what points can the guide vane apparatus be adjusted to optimize its performance with the turbine?

"As far as I know, there's usually only one VTG adjustment screw for this, which is adjusted on the loader test stand. But that shouldn't affect whether the VTG engages or disengages between the adjustment points, right?"


Einen verdichtergehäuse-beschichteten Lader auf der Strömungsbank einzufahren und die ersten Schmirgel-Umdrehungen evtl. per Hand zu machen, wäre irgendwo logisch. Abhe

Quote:

The coating is worn off during the initial start-up of the charger.

That sounded more like a break-in period for the motor to me...

Hi Ulf,

Unfortunately, the axial clearance cannot be adjusted quickly. It can only be adjusted through mechanical modification of the turbine housing or by changing the impeller design. ATL manufacturers produce certain prototype parts to test the upper and lower tolerance limits, or you can contact the ATL specialists mentioned above.

As far as I know, there are no ball bearings that can withstand such high speeds. I can take a look at SKF.

It's good that the topic has been "expanded" a bit more.
@ Ulf
It was obviously referring to the initial commissioning of the equipment on the flow bench.

I've been searching for a turbocharger optimization for a long time, and it's not easy to find something suitable, especially for diesel engines.
I then found the company Grundler Motorsport online. I can't really judge how competent they are, but the information I've received from them so far is consistent and gives the impression of expertise.
Let's go back to the optimization...

The coatings applied to the compressor housing are known from the commercial vehicle sector and can increase the efficiency of the turbocharger by up to 2%. Equipped in this way, the turbocharger should be able to provide approximately 1.7 bar of boost pressure.
The question is whether this will negatively affect the durability (based on a boost pressure of 1.5 bar) in any way.

I'm interested in knowing if there are any other optimization possibilities, or if other turbochargers might be a good fit, such as ball-bearing turbochargers. What is used in racing (probably modified VNT20s), but I don't want power to only start above 3000 RPM.
Has anyone here had any experience with Grundler Motorsport?
How does the optimization of the compressor side behave when the storage is no longer 100% reliable, and is it possible to roughly estimate this without using special measuring devices?
Many questions, but I don't think I'm alone in my thoughts...

Zak1976 wrote:

Which company did you use for this? Do you have a link (via private message) or a phone number? What was the total cost (including the new battery)?

I had it done at http://members.aon.at/turbocraft/.

Unfortunately, I can't tell you the cost because a relative of mine works there and they provided it to me for free.

The company specializes in turbochargers... I can only recommend them.
(Performance enhancement, turbocharging, fuel consumption reduction, emissions reduction (Euro 1, 2, 3, 4), torque optimization, prototype and pre-production series for OEMs)

schnappi wrote:

As far as I know, there are no ball bearings that can withstand such high speeds.

I'd like you to try running my turbocharger. The feeling (compared to the typical, wobbly Garrett oil-immersed bearings) is something I can only compare to a ball bearing for me -> absolutely no noticeable play, and endless spinning even when the engine is off.

As far as I remember, my turbocharger used what are called "needle bearings."

fricki wrote:

In my turbocharger, what I believe were called "needle bearings" were used.

Okay, needle bearings could also be the problem with my loader...

Are there conversion kits available to replace the bearings in the Garrett VNT1749VB turbocharger with ball bearings?