[vamsi.vadrevu]

I was reading through some material online about the technology used by Nissan in their HRA0DET engine. It was mentioned that it uses a technology called Mirror Bore Coating on the inside surface of the engine.

https://www.nissan-global.com/EN/INN..._BORE_COATING/

As I was researching what it meant, I came across this video on youtube which explained the difference between the types of engine blocks.

https://youtu.be/dIjtap8GLF8

Traditional Engine Blocks are Cast Iron blocks and they're rarely used these days.

Modern engines use Aluminum cylinder blocks with steel sleeve inserts which serve as the cylinder bore. (Aluminum, being a soft metal, can't withstand the friction of pistons cycling up and down those many times). So engineers insert a 2mm to 4mm thick steel or cast iron cylinder inside the aluminum engine block inside which the pistons are inserted. The downside of this is that the cast iron or steel isn't a good enough conductor of heat. Consequently, for high performance applications (where heat needs to removed quickly like in race cars and F1), they don't bother with any sleeves or liners. Instead they use linerless engine blocks or use coatings such as what Nissan uses in GT-R engine. These coatings are basically molten steel or iron sprayed with a thickness of 0.2mm. This improves the conductivity while maintaining sufficient wear characteristics necessary for a high performance engine.

Now, my concern and fear is that these linerless engine designs are more suited to racing engines because they aren't meant to last a million kilometers. The problem is Nissan is using this technology on their daily run-about engines, which are ideally meant to last at least 1 to 2 lakh km. I'm not sure how advanced and mature these coatings are, but can anyone comment on how reliable these coatings are? Do they last long?

If someone in the mechanical industry can comment on this, it would be really great! I've already purchased Nissan Magnite Turbo CVT, but I'm just concerned about the longevity of the engine now! (I would hate to experience buyer's remorse now!)

I guess this makes the regular maintenance all the more important for Nissan Magnite. I wouldn't want that thin lining to wear out prematurely because I delayed my engine oil change by a 100 km!

[GTO]

Originally Posted by vamsi.vadrevu

I was reading through some material online about the technology used by Nissan in their HRA0DET engine. It was mentioned that it uses a technology called Mirror Bore Coating on the inside surface of the engine.

Moving your query out to a new thread, Vamsi.

[Jeroen]

Originally Posted by vamsi.vadrevu

I guess this makes the regular maintenance all the more important for Nissan Magnite. I wouldn't want that thin lining to wear out prematurely because I delayed my engine oil change by a 100 km!

That is never going to be a problem on any engine. You can overrun the engine oil change by a good margin.

I am not familiar with this new process. I would be interested to learn how they hone it afterwards applying this layer. The honing proces is likely to give some idea about longevity as well.

I wonder why they call it mirror coating? The inside of a cilinder liner is never mirror like. If it is, it is a sure sign of profound wear. (Like ai experienced on the liners of my Alfa Spider). Cilinder/liner walls have a honeycomb type of mess honed into them for proper oil distribution and oil adherence. I wonder if Nissan does anything different here?. My first thought the naming is a PR trick.

0,2mm thickness might not sound much, but in terms of (car) engines it is a lot. Because of course for the diameter you need to double it. 0,4mm wear on cilinder diameter is a lot!

There have been other ways to improve the longevity of cilinder(liners) whilst still maintaining and improving engine efficiency. It has also been done with coatings before on normal production cars/engines.

The so called Nickasil layering from the late 80/90s springs to mine as used by Jaguar. Turned out to be a disaster in combination. With certain fuels. But since, I can’t recall any problems with liner coatings.

But given this is a Nissan I would not worry at all. These guys know what they are doing. How often do you see a Nissan broken down by the side of the road? And you have a brand new car, covered by warrantee.

Would be interesting to hear from a member who has some more knowledge of this process.
Enjoy your new car
Jeroen

[NomadSK]

Originally Posted by vamsi.vadrevu

Now, my concern and fear is that these linerless engine designs are more suited to racing engines because they aren't meant to last a million kilometers. The problem is Nissan is using this technology on their daily run-about engines, which are ideally meant to last at least 1 to 2 lakh km. I'm not sure how advanced and mature these coatings are, but can anyone comment on how reliable these coatings are? Do they last long?

That’s how the new technology percolates for common users like us when they are tested in extreme environments/conditions. Those race engines work somewhere in the range of 18-20K RPM, how much would be the RPM of your car engine at 100-120kmph, I guess it must be around 3-3.5K range. That’s like not even 30% of the extreme scenario.

Now coming to the mechanical and chemical part of the engine, there are primarily 2 factors which govern the construction of the engine, weight and efficiency. With reduced thickness of the coating, crankcase can be downsized. Cutting the long story short, the coating is a process where the weight of the engine is reduced and efficiency is increased. By replacing the heavy iron liners with the typical coating with a thin layer, smooth cylinder coating, friction losses between piston/casing can be significantly decreased, which eventually will turn into increased efficiency.

It might sound as coating, but they are applied/sprayed metals in molten form to the cylinder bores. Generally termed as Plasma/Thermal spray, with a mirror like finish. Different manufactures have their own built-in practices to carry out this process. The challenge engineers face is the adhesion of this coating to cylinder-bore/surface. Which I’m sure they must have taken care of.

They are extremely reliable and last long as any steel liner in engine would be.

Note- We carry out such metallic coatings where we get corrosion/erosion losses in the metals to enhance the service life of our equipment.

[greenhorn]

Here's an article with a bit more info
https://www.autoblog.com/2019/04/25/...oating-altima/
Googling for the process used - plasma-transferred wire arc (PTWA) seems to bring up a lot more info, and this process seems fairly widely used

Here's a short video of it in action

https://www.youtube.com/watch?v=7mJDhE1Qt68

[vamsi.vadrevu]

Originally Posted by greenhorn

Here's an article with a bit more info
https://www.autoblog.com/2019/04/25/...oating-altima/
Googling for the process used - plasma-transferred wire arc (PTWA) seems to bring up a lot more info, and this process seems fairly widely used

Here's a short video of it in action
https://www.Youtube.com/watch?v=7mJDhE1Qt68

I did find a Magnite factory tour video showing the process of depositing the layer of iron/steel with plasma arc and pressurized gas.

https://youtu.be/QSCUQjX1aBw

At 1:12, the video shows the cylinder bores being sprayed with molten metal in the Chennai Factory. It's very similar to the process in the video you posted.

This technology seems to be fairly portable. There are other videos of people spraying the molten metal onto other equipment with a hand-held device.

https://youtu.be/W7wJZTK8ec8

Perhaps this technology can replace the re-boring activity that is usually performed during engine rebuilds. If they can spray on a new coating of metal to re-surface the cylinder walls, there wouldn't be a need to increase diameter of cylinders during engine re-builds. Instead of removing metal, they can add thin layers of metal! Perhaps someone with more experience in engine rebuilds can validate this theory.

[Rajamass]

Originally Posted by vamsi.vadrevu

I was reading through some material online about the technology used by Nissan in their HRA0DET engine. It was mentioned that it uses a technology called Mirror Bore Coating on the inside surface of the engine.

https://www.nissan-global.com/EN/INN..._BORE_COATING/

As I was researching what it meant, I came across this video on Youtube which explained the difference between the types of engine blocks.

https://Youtu.be/dIjtap8GLF8

Traditional Engine Blocks are Cast Iron blocks and they're rarely used these days.

Modern engines use Aluminum cylinder blocks with steel sleeve inserts which serve as the cylinder bore. (Aluminum, being a soft metal, can't withstand the friction of pistons cycling up and down those many times). So engineers insert a 2mm to 4mm thick steel or cast iron cylinder inside the aluminum engine block inside which the pistons are inserted. The downside of this is that the cast iron or steel isn't a good enough conductor of heat. Consequently, for high performance applications (where heat needs to removed quickly like in race cars and F1), they don't bother with any sleeves or liners. Instead they use linerless engine blocks or use coatings such as what Nissan uses in GT-R engine. These coatings are basically molten steel or iron sprayed with a thickness of 0.2mm. This improves the conductivity while maintaining sufficient wear characteristics necessary for a high performance engine.

Now, my concern and fear is that these linerless engine designs are more suited to racing engines because they aren't meant to last a million kilometers. The problem is Nissan is using this technology on their daily run-about engines, which are ideally meant to last at least 1 to 2 lakh km. I'm not sure how advanced and mature these coatings are, but can anyone comment on how reliable these coatings are? Do they last long?

If someone in the mechanical industry can comment on this, it would be really great! I've already purchased Nissan Magnite Turbo CVT, but I'm just concerned about the longevity of the engine now! (I would hate to experience buyer's remorse now!)

I guess this makes the regular maintenance all the more important for Nissan Magnite. I wouldn't want that thin lining to wear out prematurely because I delayed my engine oil change by a 100 km!

Interesting observation

The VW EA211 new engine update also mentions that the engine cylinder liners are plasma coated with iron powder and VW claims it to be extremely efficient in handling friction between cylinder liners and piston rings.

EA211 (1.5TSI) engine is used in the many cheaper VW cars like Jetta and Taos

https://media.vw.com/en-us/press-kit...-gli-press-kit

Check under powertrain sub heading in the above link

[Jeroen]

Originally Posted by vamsi.vadrevu

. Instead of removing metal, they can add thin layers of metal! Perhaps someone with more experience in engine rebuilds can validate this theory.

Don’t think that will work. Revoking is only done if there are no liners to replace..

It’s a slow and tedious job and after applying the coating you would still need to turn it and hone it to the correct dimensions. You can’t spray this stuff on to correct thickness and evenness. That always comes by ways of turning/honing.

Replacing liners is very easy and straight forward. Maybe we will see liners that have this coating on it and are pre-cut and honed to correct dimensions.

But I don’t think they are using this coating for less wear. Check out the forum, how many members have reported their cilinder needed boring out or liners replacing. I only know of one, me. On my 1986 Alfa Romeo Spider after some 250.000 km and the engine running too rich. Go figure.

The main factor I would think is resistance which helps engine efficiency, maybe also less lub oil, which again is a gain in efficiency .

Jeroen

[vamsi.vadrevu]

It seems the primary driving factors for manufacturers going for liner-less cylinders is

1. Weight reduction
2. Better Heat dissipation (aluminum is an excellent conductor of heat. So, the lesser material we have between the actual aluminum cylinder wall and the heat exchange fluid, the better performance we can get)
3. Lower cost of manufacturing

Whether these advantages are realized at the expense of longevity is my main concern.

As NomadSK had mentioned, at the RPMs we would typically operate our engines, we may not even touch 30% of it's service limit. I'll still refrain from revving the engine to redline, just to be on the safe side.

Someone on the main Nissan Magnite thread had covered 73000km without any issues. I would probably need to ask what their usual driving habits are like!

[Jeroen]

Originally Posted by vamsi.vadrevu

As NomadSK had mentioned, at the RPMs we would typically operate our engines, we may not even touch 30% of it's service limit. I'll still refrain from revving the engine to redline, just to be on the safe side.

Why?

Cilinder wear is a function of several parameters. But the most relevant one tends to be time. Cilinder wear is minute but continuous. But contrary to popular thought it is not necessarily linear with engine RPM.

Rule of thumb, the largest contributor to cilinder wear are cold starts and prolonged idling with the engine not at normal operating temperature yet.

A bit of red lining now and then won’t harm your engine at all.

Jeroen

[vamsi.vadrevu]

I was just reading through a few articles and found this curious article by Autocar.

https://www.autocarpro.in/news-inter...-engines-67206

It seems Volkswagen also uses this Plasma coating technology on its TSI engines.
Both the 1.0 TSI and the 1.5 TSI are coated with Plasma on their internal cylinder surfaces.

It seems that this technology has already gone mainstream. Happy to see that tech is percolating down into an average Joe's car!