Nissan Mirror Bore Process

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https://www.greencarcongress.com/2019/04/20190426-nissan.html
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...Nissan's Decherd assembly line is using a mirror bore process in the all-new 2019 Nissan Altima 2.5-liter engine......This will mark the highest volume application of the technology within Nissan. The team in Decherd assembles an engine every 19 seconds and is capable of building about 1.4 million engines a year.... ...The mirror bore treatment, first used in the Nissan GT-R and applied to other specialty models such as the Sentra NISMO, eliminates the need for bulky cylinder liners and raises energy efficiency by reducing the friction inside the engine.... ...Rather than inserting a cylinder liner, mirror bore coating technology sprays molten iron onto the surface of the cylinder bore and forms an iron coating layer on the walls inside. By giving this a mirror-like finish, the drag that arises when the piston is operating can be reduced.... a special drill bit is used containing tiny bits of diamonds that were unfit for jewelry. The bit is spun at high speed inside the cylinder to polish the metal until shiny and smooth—giving the process its "mirror bore" name and the cylinder walls a reflective surface... ...compared to the roughly 2mm-thick cylinder liner, the 0.2mm mirror bore coating is extremely thin, making for better heat conduction. This results in better cooling performance and less engine knocking... ...[this new engine] also adopts a resin intake port. The resin port is inserted into the intake port cast in the cylinder head, thereby forming an air layer between the intake air passageway and the head inner wall so as to suppress the rise in intake air temperature. This world's first application of a resin intake port improves anti-knock performance, thus contributing to improvements in combustion efficiency and power output...
 
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Originally Posted by WyrTwister
I thought a cross hatch finish was needed either to help the rings " seat " or to hold engine oil ?
Why hold it when you can just burn it?
 
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For lubrication . I once read that since cast iron is somewhat porous , it is an advantage for cylinder bores . Since it absorbs and holds a little oil ?
 
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Smooth bores have been used for decades in some applications, chrome bores were very common on 50cc mopeds in the 80's. Oil control seemed to be an issue with 4 stroke engines, on 2 stokes it was not an issue as it was burning oil mix anyway.
 

MolaKule

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Originally Posted by WyrTwister
For lubrication . I once read that since cast iron is somewhat porous , it is an advantage for cylinder bores . Since it absorbs and holds a little oil ?
An engine block casting is not porous in the sense of a sponge. There are "closed pores" along the cylinder wall that may trap oil for lubrication and catch debris during run-in. Chrome-lined or chrome-plated cylinder walls reduce wear and friction. When a cylinder wall has a very fine or mirror finish, the rings must be pocked with laser engraved pockets to retain oil. https://www.sciencedirect.com/science/article/pii/S0301679X17302256
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...Whether it be crosshatch Honing, or the laser texturing of bore and liners, the valleys: The valleys provide for oil storage, provide a reservoir for early wear debris to keep the debris from agglomerating and causing subsequent scuffing, and speed up tribofilm formation. Below is an electron photomicrograph of a worn section of a cylinder bore in which the sliding direction is North-South(1). In laser texturing, the effects have been attributed to pressure buildup of the oil trapped in the closed pores. What needs more study is the effect the channels have from crosshatch honing with respect to lubrication and wear. It appears the early machinists were right after all. 1. Becker and Ludema, A Qualitative Empirical Model of Cylinder Bore Wear, Wear,: 225-229, 1999.
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/5075599/run-in#Post5075599

Cylinder Bore Microphotograph.jpg
 
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Nah. no thanks. Nissan since their Renault joint venture build total JUNK vehicles. I wouldn't own a newer Nissan if someone paid me to do so. I can't wait to hear of oil burning issues and other failures related to this joke process once it is mass driven and on the streets of America. Anyone think "Chevrolet Vega" days ahead?? smile And I love the pathetic attempt to explain the finishing of the bore... a Drill bit with diamonds??? Really?? LOL it is nothing close to a drill bit. It is called a boring bar with diamond tipped cutters.
 
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You are not going to rebuild one of these blocks. Can't be turned out to the next size. I first heard of this kind of thing in the late 70's, Kawasaki was doing this with their dirt bikes.
 
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It sounds like fascinating technology. If the grooves and crosshatching are needed to capture oil for lubrication then I'm guessing the engineers figured out the most efficient way of producing those features. And no, this is not the Vega. GM was looking ahead to aluminum for block material but it was not ready for prime time.
 
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Nothing new - the Germans and Ford have been using something similar, I think it's plasma arc coating. Let's see how well this works, BMW and Jaguar had issues with high-sulfur fuel and Nikasil in the US and the 3rd world.
 
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Originally Posted by nthach
Nothing new - the Germans and Ford have been using something similar, I think it's plasma arc coating. Let's see how well this works, BMW and Jaguar had issues with high-sulfur fuel and Nikasil in the US and the 3rd world.
Yeah and isn't it Audi that uses Laser finishing? Could be wrong but I'm sure I read that somewhere.
 
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Originally Posted by nthach
Nothing new - the Germans and Ford have been using something similar, I think it's plasma arc coating. Let's see how well this works, BMW and Jaguar had issues with high-sulfur fuel and Nikasil in the US and the 3rd world.
My K75C BMW bike had Nikasil lined cylinders...ran 4000+ RPMs on the road for 150,000 miles. Never burned oil till the day I wrecked it.
 
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Originally Posted by nthach
Nothing new - the Germans and Ford have been using something similar, I think it's plasma arc coating. Let's see how well this works, BMW and Jaguar had issues with high-sulfur fuel and Nikasil in the US and the 3rd world.
Alusil had the issues. Nikasil was the answer.
 
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Originally Posted by Trav
Nikasil was the problem, later alusil blocks were the answer. You almost had me confused. LOL https://www.looking4spares.co.za/web-articles/211-alusil-vs-nikasil
Well [censored] if I didn't have myself confused. I remember shopping for a 5er years ago and even in Germany there was talk about some being a problem and others not being a problem and the 530i vs the 540i. So I bought a 750i. Turns out that had Alusil liners as well. Thought they were Nikasil all this time. In any case, the cylinders were perfect at 390,000km.
 
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It's 'real funny, 'cause if memory serves me aircooled Porsche's with Mahle-made Nikasil barrels and sometimes with Kolbenshmidt-made Alusil barrels - both had / have fantastic life expectancy. The only difference between the two is that when re-ringing them... with standard piston rings - the Nikasil barrels were able to be deglazed using scotchbrite... whereas you could NOT do that with the Alusil. Does anyone know about these, and their durability?
 
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