35 replies to this topic

[MatsNorway]

Are there any choices? I was toying with the idea of thinner sylinder liners

 

http://en.wikipedia....ensile_strength

Tungsten is interestingly lower than Steel, 2800 Maraging steel^[7] who is at 2693mPa at ultimate tensile.

 

There are a lot of fancy materials (ceramics++) but it is hard to find the strenght on them.

 

I was thinking aluminium oxide at first https://www.ceramici...rial-Charts.pdf

But it lacks strength in um.. pull direction. After some more googling it actually also got less heat transfer capasity than Steel.

Edited by MatsNorway, 19 August 2014 - 20:10.

[Fat Boy]

It's almost like it's your own personal mission to destroy this board.

[MatsNorway]

Discussing/hearing/learning about sylinder liner materials sounds to me like a perfectly good discussion suitable for a technical forum. No more offtopic please, you have been bringing a negative tone and not much else lately.

Edited by MatsNorway, 19 August 2014 - 20:28.

[John Brundage]

I was attending a factory Cummins training school over twenty five years ago. During the class the Cummins instructors told us about an engine they were testing that had ceramic cylinder liners. The engines were being tested in very cold climates by the military. They found that there was not much heat transfered to the cooling system which in turn meant no heat for the operators of the equipment that had these engines.

[bigleagueslider]

Aluminum with a Nikasil bore coating has a much harder wear surface than steel and much better thermal conductivity across the liner wall thickness than steel. This construction has been widely used for many years in recip engines.

[Kelpiecross]

The cylinder liners I have seen (the type that are pressed into the block - not "wet" liners) are surprisingly thin - about 1/16 of an inch thick - so it would be difficult to save any useful amount of weight.
What would be best - less or greater heat transfer from the cylinder?

[Tenmantaylor]

What is everyone's favoured method of heat transfer? Mine is W/mK! And aluminium is a damn good conductor of heat, much better than steel. Why it's the standard heat sinking material for pretty much any passive heat dissipation device even though it's a lot more expensive than steel. It's also a hell of a lot lighter.

Edited by Tenmantaylor, 20 August 2014 - 14:51.

[Barbapapa]

I've made liners from hardened alloy steel and had them Nikasiled. They are certainly strong and I was able to make them with a thin 'coat tail' and give the piston skirts full support.

Having done that I would make them out of aluminum (Nikasiled) next time in order to have similar expansion rates and closer clearances. I don't think the heat conductivity matters in my case but closer clearances are definely a good thing.

 

I'm not aware of any materials that are practical to use by themselves without coating. There always seem to be things under development in OEMs though.

 

In the past, nascar engines were using thin steel nikasiled inserts in their cast iron blocks. F1 seemed to have various nikasil like or similar coatings, some applied directly to parent block material. There's a lot of variety but not big gains to be found, nikasil is pretty good and hard to improve on.

 

Getting away from known materials can lead to compatability problems with rings. Nikasil requires non-chrome oil rings and other materials outside of common cast iron can have big problems you may not realise until trying certain ring materials.

 

This is a good topic, thank you for putting it out there.

Edited by Barbapapa, 20 August 2014 - 17:28.

[MatsNorway]

Some of my thoughts on inserts and so on is from heavily boosted engines. Some even fill the cast with concrete and epoxy to make them stiff enough. So i thougth about exotic inserts as a way of making things stronger, lighter and with better cooling.

[Barbapapa]

Maraging steels have no helpful properties. It's going to be hard to improve an old fashioned cast iron liner for a boosted engine stretching it's intended design parameters. Why do you feel heat conductivity matters?

[Canuck]

Beryllium matrix materials. You* can't get them and they're not legal in many (any?) sanctioned racing that I'm aware of, but it's hardcore stuff. Once upon a time I was in touch with a company in the UK about just such a thing for a motorcycle project but the cost estimates were quickly spiralling into the realm of absurd for mere mortals.

*assumes you are not working with the funds of a Russian oligarch.

[Lee Nicolle]

Maraging steels have no helpful properties. It's going to be hard to improve an old fashioned cast iron liner for a boosted engine stretching it's intended design parameters. Why do you feel heat conductivity matters?

I agree. And you have to get rid of the heat somewhere. IF the liner does not absorb some it all goes into the head. Maybe good for power but all sorts of weird expansion rates. And potentially all sorts of detonation issues too. As well as sealing issues.

[MatsNorway]

You have to say that differntly Lee. Makes no sense for me reading it now.

[gruntguru]

I agree. And you have to get rid of the heat somewhere. IF the liner does not absorb some it all goes into the head. Maybe good for power but all sorts of weird expansion rates. And potentially all sorts of detonation issues too. As well as sealing issues.

If you insulate the bores - the bores get hotter, less heat goes into the cooling system, more heat stays in the gases. That's a good thing.

 

Hot bore means hot piston plus lubrication breakdown. That's a bad thing. (two bad things actually)

Edited by gruntguru, 28 August 2014 - 02:06.

[bigleagueslider]

Maraging steels have no helpful properties. It's going to be hard to improve an old fashioned cast iron liner for a boosted engine stretching it's intended design parameters. Why do you feel heat conductivity matters?

With a cylinder liner, what matters is the compromise between material tensile strength, thermal conductivity, and material stiffness. The reason the material thermal conductivity matters is because if the heat transfer rate across the cylinder wall is not sufficient to keep the temperature at the liner bore surface low enough to prevent the lube oil film from flashing, then the piston rings will experience scuffing failure.

[Tenmantaylor]

I imagine Graphene (amongst nearly any other high performance application) would make a pretty awesome cylinder liner.

[Lee Nicolle]

If you insulate the bores - the bores get hotter, less heat goes into the cooling system, more heat stays in the gases. That's a good thing.

 

Hot bore means hot piston plus lubrication breakdown. That's a bad thing.

Agreed, I should have said that.

[MatsNorway]

I get the rest you posted now Lee. More heat staying in the gases is not really a consern. You can allways add more compression or boost.

[Lee Nicolle]

Mats, more comp or boost makes more heat which adds to the ring temp, piston temp problems. An engine is a heat pump, but it has to be mechanically viable or it will last a very short time. Heat makes power and will kill an engine quick smart too. A fine line often exceeded.

 

That is why F1 technology, or most racing technology is no good for a road car. 

The reason a fuel Dragster engine is rebuilt after every run, even some alcohol ones are too.

 

Even simple stuff such as long rod engines while feasible will not last as long as the OEM combo normally. And most turbo engines still create a series of ashtrays from pistons, even in Production racing where mods are VERY limited

 

Fuel economy engines are heavily lagged to keep the heat in the engine but still have to be cooled via a radiator. low speed and performance engines.

Many modern engines will allow the engine too limp home mode with little or no coolant. Though the life of the engine is very suss after!

[ladaok]

what are you after ? , strength, lightness, wear resistance, thermal conductivity etc,  ... pretty hard to get every thing in one metal package, the more you get the  >>> + the cost 

one of the best I've seen was in a Porsche engine ... hard chromed bores, but the suface had lots of tiny pits to hold oil on the bore,  I guess you could do this with acid etching or photo engraving before the plating process 

[bigleagueslider]

Given the bore diameter and cycle pressures/temperatures in most SI engines, a cast aluminum block with integral liners and a bore coating like Nikasil is the best approach. The integral cast cylinder walls and deck surface provide the most efficient structural arrangement and give the best heat transfer at the upper end of the cylinder bore where it is most critical. The silicon nitride ceramic particles at the wear surface of the cylinder bore are extremely hard, and much harder than chrome or hardened steel. After the Nikasil coating is finished honed, the nickle matrix surrounding the silicon nitride particles is a few microinches below the surface of the ceramic particles, and this results in a very thin layer of lube oil being trapped in the space between the ceramic particles. It creates the ideal conditions for boundary lubrication of the piston ring contact surfaces.

[MatsNorway]

ladaok im after knowledge!

 

Porsche does not use nikasil btw. they use alusil. Wiki article on Nikasil is wrong. Due to some fuels having sulfur? and it ate away something in the nikasil layer. http://en.wikipedia.org/wiki/Alusil

 

Its clear that any material having comparative strenght could be used over steel as long as it has better termal conductivity. Thats the short versjon. Lee, Grunt++ covered the pros and cons.

 

But ive not found an ceramic that seems suitable.

Edited by MatsNorway, 24 August 2014 - 08:46.

[bigleagueslider]

Take a look at Al-Be alloys. They have an elastic modulus comparable to steel and excelent thermal conductivity. However, the material is very expensive.

 

You might also look at some of the aluminum MMC materials that have been used as cylinder liners.

[Fat Boy]

Hey Mats, Sorry I couldn't get back to you earlier, but here's the deal. When you tell me to **** off, then have the balls to leave it up for all to see. You're certainly not the first or last to convey that sentiment and I've got skin thick enough to handle it.

 

You're posts are annoying. I could go deeper into it, but why bother? I'm not looking to debate the issue, I'm just stating my opinion.

 

Have fun with your alchemy.

[Kelpiecross]

I have to speak up in defence of Mats - he continually comes up with topics to discuss - without him this forum would be a lot duller. The same goes for the late lamented Cheapy.

[gruntguru]

Diamond meets your criteria perfectly Mats. Five times the thermal conductivity of Copper and many times harder than the hardest steel.

 

Your engine will be an absolute jewel.

Edited by gruntguru, 28 August 2014 - 05:34.

[desmo]

I read somewhere that diamond has the highest thermal conductivity of any known material and is pretty hard as well. They will weigh a ton compared to your AlBeMet liners though.

[Fat Boy]

I have to speak up in defence of Mats - he continually comes up with topics to discuss - without him this forum would be a lot duller. The same goes for the late lamented Cheapy.I'

 

I'm really not trying to derail this, and I'll drop it from here.

 

There are 3 major differences between Mats and Cheapy.

 

1. Cheapy was always interested in things that had real life applications and they were often problems that he was trying to solve at the time.

2. Cheapy got stuff done. He didn't just pontificate about vaporware.

3. Cheapy started conversations with more of a first-page-google amount of research on the subject.

 

OK, I'm done...I promise.

[Canuck]

I have found that, in every area I have looked at with an engine, people much smarter and better resourced than I are already hard at work on the same or similar solutions. I wouldn't suggest that someone here will never come up with an original solution to a known problem, but "stronger better" isn't an original solution. AlBeMet liners from Perfect Bore were already in play over a decade ago. The answer to your question is both already there and readily available if you choose to spend the money and not race anything sanctioned.

[MatsNorway]

My initial response (edited long before you replied to it...) was overly aggressive and im sorry i lashed out offending your diva tendensies making you go into a full steaming meltdown culuminating in petty remarks.

 

Forum for me is not all about the sickest first post. Its often about where we end up as well as the stories inbetween and some fun offtopic. Also i would never have found the info below without some pressure/drive to prove someone wrong.

 

Would like to hear the thoughts on these liners by the rest of you. I enjoyed your previous posts Lee++

http://www.alueurope...der-linings.pdf

 

"This chapter will cover all applicable concepts, but focus in particular on separate cylinder liners."

"Wear-resistant cylinder liners which consist of a hypereutectic AlSi alloy were developed byPEAK Werkstoff GmbH as a lightweight alternative to the considerably heavier cast iron cylinder liners, but also as an alternative to the relatively expensive monolithic engine block made from the hypereutectic primary AlSi17Cu4Mg (ALUSIL®) casting alloy. The cylinderliners can then be cast-in, preferentially using the high pressure die casting process with alower cost (secondary) AlSiCu casting alloy."

 

What is Silitec?

A decent sum up from this guy below: http://www.finishing...3799/3605.shtml

 

"Cylinder sleeves, or liners, in the crankcases of newly designed V6 and V8 engines from Mercedes-Benz AG in Stuttgart, Germany, are made of a special aluminum-silicon alloy that enables piston-ring tension to be reduced by nearly 50 percent. The new low-friction alloy composition also improves heat transfer in the housing, and provides greater stiffness and lower weight for the aluminum blocks.

A new low-friction aluminum-silicon alloy in the cylinder sleeves of Mercedes-Benz production engines reduces piston-ring tension by half.

In addition, the reduction in cylinder distortion (higher dimensional stability) that is possible with this alloy results in less noise and friction; engine-oil consumption and exhaust emissions are thus reduced. Mercedes-Benz is the first automaker to use the innovative Silitec material in production.

Aluminum die-cast engine crankcases are normally fitted with gray cast-iron cylinder sleeves or cylinder barrels with a galvanized nickel coating to avoid high friction from surface pores that form on the cylinder walls produced in conventional die-casting operations. The new liners are manufactured from a hypereutectic aluminum-silicon-copper-magnesium alloy that is spray-compacted while it is cooled in a nitrogen-rich atmosphere, producing billets with an optimal microstructure. The billets are then formed into cylinder liner blanks in an extrusion press.

Finally, the blanks are specially treated in an environmentally friendly process, aqueous exposure. The resulting smooth surface structure improves friction characteristics and cuts the engine's oil consumption and hydrocarbon-emissions levels. The new cylinder-barrel finishing technology, which includes both the material composition and the surface treatment, was developed by Mercedes-Benz with a partner company."

 

Another one i have not yet read: http://www.ewp.rpi.e...aft_4_14_11.pdf

 

Have fun with your alchemy.

You would have said the same thing about Nikasil if that was suggested today.

 

Hey Fatboy.. congratulations on losing credibility and proving your narrow mindedness all while achieving basically nothing.

 

Im going to continue to make posts more or less in the same way as i have. Sylinder liners is interesting, it's not alchemy and i dare say it is something most here found interesting. Lets continue shall we?

Edited by MatsNorway, 28 August 2014 - 21:08.

[bigleagueslider]

It is a bit misguided to only consider the liner composition by itself. Like anything else with regards to the design of a recip IC engine, what matters is the total result of the design. This would include factors like weight, thermal efficiency, durability/reliability, cost, structural efficiency, etc. You cannot design any individual engine component in isolation. Every engine component must be designed in context of the complete engine system.

 

Even if you had the perfect material, in terms of wear and heat transfer, to use for your cylinder liner, how much of an overall improvement would that actually produce in the typcal engine versus using the best conventional cylinder liner materials?

[MatsNorway]

BigL im just going to quote the papers above. If you read it all you will find that Ford used thermal spraying on their 500hp+ mustang engine and leased the technology to Nissan for their 500hp+ GTR

 

ALBOND® (developed by MAHLE) is another solution particularly suited as a cast-in material for aluminium die cast engine blocks. Cylinder liner compounds are separately cast using hypereutectic AlSi alloys and later cast-in into the engine block. The distance between the cylinders can be reduced, a more compact engine design is made possible, and, depending on the design of the cylinder liners, the weight can be reduced by up to 400 grams per cylinder compared to cast iron liners.

 

Hypereutectic Al-Si alloys have the necessary wear resistance for the cylinder block bore surface with a thermal conductivity of nearly 400% higher than that of cast iron

 

For instance, Toyota with their 1.8 liter four cylinder 2ZZ-GE engine, was able to produce 26.17% more horsepower and 4.65% more torque with the same 1.8 liters of displacement as the 1ZZ-FE that uses cast iron liners [28]. In the case of cast iron liner designs, the maximum temperature between the bores would exceed the allowable limit. Focusing on high-temperature strength of the sealing area between the bores, Toyota concluded that the MMC bore design has an advantage for shorter bore-to-bore distances considering all aluminum block designs [28]. The MMC bore material has a higher young’s modulus [Fig. 4, 28], higher tensile strength at elevated temperature [Fig. 5, 28], and higher compressive strength [Fig. 6, 28] than a hypoeutectic aluminum alloy with similar mechanical properties as A380.
Lokasil® the MMC, patented by KS-ATAG, prov

 

 

Ford’s PTWA process was considered a success with the test data to back it up. Results from Ford’s testing showed that friction was greatly reduced, on average 6.8% below the values characteristic of traditional cast iron liners and 14.1% below cast-iron engines [16]. At large, PTWA coated engines had increased miles per gallon of gasoline, reduced wear, weight, and cost compared to their cast-iron counterparts [52]. In 2009, the engineers who perfected the PTWA deposition technique received the National Inventor of the Year Award.

[Kelpiecross]

As someone wrote previously - why would a thermal conductivity 4X (or is 400% 5X) that of iron be a good thing?

[MatsNorway]

You can run a higher compression i think, thought it said so in one of the papers. Less localised heat. But someone else has to shime in on that.

[Lee Nicolle]

What most seem to have forgotten here is expansion rates. Driving a V8 petrol Landcruiser with an alloy engine that rattles like blazes when cold. Drive it a km and no noise. Just like most alloy engines. Listen to a V8 Chev/Holden and they are worse. Or an alloy Sprintcar engine.

Whatever the liner everything has to expand in a coordinated manner. And I suspect these superhard materials will be worse. Modern piston material is far more stable. Remember old forged pistons with 7 thou clearance in a 4" engine. Very rattly until they warmed up. Modern ones use half that, as do hyperuetectic less again. Though for race use you still need more clearance or the skirts will scuff real bad.

Modern rings too have about half the tension of even 30 years ago. And last really well. And the bores seldom lip or mark up.Though you HAVE to use better oils.

So why on earth try to reinvent something that works well now. Long distance high performance road engines, motorsport engines all last longer and dont wear out nearly as much.

The only disclaimer to that is ofcourse forced aspiration engines [especially turbo] pushed beyond sensible boost. Then the pistons become ashtrays, bores are stuffed as well as cranks, rods, bearings.

Because people are trying to make stupid power out of engines that are not suitable.

[bigleagueslider]

Mats- the PWTA plasma spray bore coating process you noted is composed of a ferrous (iron based) material. While the ferrous coating is quite thin, the conductive heat transfer from the bore surface to the coolant must still first pass thru this ferrous metal layer. The reason the OEMs like the PWTA process more than something like Nikasil for coating aluminum cylinder block bores, is because the PWTA process is far cheaper to use in production and works just as well as Nikasil.

 

While aluminum blocks cost far more to use than CGI blocks in production applications, they have the advantage of being lighter and also allow a much tighter fit with aluminum pistons, which helps with NVH and emissions.