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  #21  
Old 02-13-2020, 06:46 PM
scsmith scsmith is offline
 
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Quote:
Originally Posted by breister View Post
Edit: I don't see anything in the link that says they don't insert a sleeve, as do other engines - only an implication that they create the cylinder in a different way than traditional cylinders. While Nickasil CAN be deposited on Aluminum directly, Iron sleeves are not expensive nor particularly heavy and it seems like it would be very risky to trust a very thin deposited layer for aircraft use. However, after searching I have found other references to monolithic aluminum cylinders, so apparently they do exist. /Edit. They could still use a sleeve of nickel-steel called a "barrel." IMHO, plain Aluminum would last about a week... Here's a good description of an aircraft cylinder from Superior Air Parts. So, after trying to answer your question I am much less certain than I was originally....
Just ask GM about how the Chevy Vega engine worked out. Aluminum cylinders coated with some new-fangled silica. I think they might have lasted longer with a coat of epoxy.
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  #22  
Old 02-13-2020, 07:04 PM
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dpansier dpansier is offline
 
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Interesting perspective on Aluminum cylinders from Sunnen the hone company.

https://www.sunnen.com/newsdetails.aspx?newsid=11
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  #23  
Old 02-13-2020, 09:50 PM
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rv6ejguy rv6ejguy is offline
 
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Plenty of modern production and race engines use Nikasil or Nikasil type cylinder coatings. Well proven and reliable as long as you don't have high sulfur content in the fuel.

Audi, BMW, Porsche, Ferrari, Jaguar, plenty of race engines, bike, marine, small engines have all used it. Rotax 912s have Nikasil coated cylinders as far as I know.
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Last edited by rv6ejguy : 02-13-2020 at 10:08 PM.
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  #24  
Old 02-13-2020, 09:52 PM
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rv6ejguy rv6ejguy is offline
 
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Quote:
Originally Posted by breister View Post
Yeah, after my earlier post I started looking around the internet. I find a lot of references to them in racing, but little or nothing having to do with reliable, long lasting use. So, that begs the question - if they are really better, why isn't anyone using them in cars or motorcycles? Steel sleeves can handle hotter temperatures and really don't weigh all that much.

This is another one of those ideas that sounds really good, but I think I'll wait until they have a few hundred thousand hours of operational data before I'll try it...
There are hundreds of millions or billions of hours on Nikasil and Alusil coated cylinders...
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Last edited by rv6ejguy : 02-14-2020 at 07:12 AM.
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  #25  
Old 02-14-2020, 02:18 AM
Andy_RR Andy_RR is offline
 
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Hypereutectic bores and (Nikasil) plated bores to two different technologies that allow aluminium blocks to run without iron cylinder liners. Both are very widely used although I don't know who is using what these days in the Auto OEM space. It's certainly not new nor mysterious and high time it makes its way into aero engines.
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  #26  
Old 02-14-2020, 06:45 AM
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mchargmg mchargmg is offline
 
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Quote:
Originally Posted by scsmith View Post
Just ask GM about how the Chevy Vega engine worked out. Aluminum cylinders coated with some new-fangled silica. I think they might have lasted longer with a coat of epoxy.
This reminds me of a time in the late 70s. My girlfriend (now wife) had a job in Oklahoma. She was driving back to see her mother in Missouri. She called me from a truck stop, her Chevy Vega had melted down on the interstate. I drove down in my mighty Rambler to the rescue. As I recall we had it towed, and the guy at the truck stop recommended we junk it, which we did.

I was never a fan of all Al blocks since that time.

cheers

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  #27  
Old 02-14-2020, 07:12 AM
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rv6ejguy rv6ejguy is offline
 
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Quote:
Originally Posted by mchargmg View Post
This reminds me of a time in the late 70s. My girlfriend (now wife) had a job in Oklahoma. She was driving back to see her mother in Missouri. She called me from a truck stop, her Chevy Vega had melted down on the interstate. I drove down in my mighty Rambler to the rescue. As I recall we had it towed, and the guy at the truck stop recommended we junk it, which we did.

I was never a fan of all Al blocks since that time.

cheers

Geoff
The vast majority of auto engines have aluminum blocks today. Many have thin iron sleeves, many have Nikasil or Alusil coated bores. Lots has changed in 40+ years since the Vega debacle.
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  #28  
Old 02-16-2020, 01:27 PM
breister breister is offline
 
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Quote:
Originally Posted by scsmith View Post
Just ask GM about how the Chevy Vega engine worked out. Aluminum cylinders coated with some new-fangled silica. I think they might have lasted longer with a coat of epoxy.
Well, that was a long time ago and as others have pointed out Porsche and motorcycle cylinders have been successful. Besides, Chevy in the years the Vega was produced did not have a great reputation.

My initial gut feeling that it couldn't work does not seem correct now - and if the parts are considerably cheaper, in the long run it may still make sense even if the cylinders needed to be replaced more often.

I would have no interest in the normally aspirated version, but replacing my O-290 with the turbocharged version would be sweet if the price were low enough.
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  #29  
Old 02-16-2020, 03:21 PM
lr172 lr172 is offline
 
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Quote:
Originally Posted by breister View Post

My initial gut feeling that it couldn't work does not seem correct now - and if the parts are considerably cheaper, in the long run it may still make sense even if the cylinders needed to be replaced more often.
My 911 with nikasil cylinders has 140,000 miles on the original cylinders and burns no oil with good compression. I don't think poor longevity is a trade off with these technologies.

Larry
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  #30  
Old 02-17-2020, 07:05 PM
Cumulo Cumulo is offline
 
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Wink Nostalgia

Thread made this old man look up Nikasil. Looks good. Requires diamond honing.

Bought an almost new Vega once with the engine parts in a box. Got a block with the stepped sleeves. Six on the floor, German racing trim. Several 2000+ x-countries. I liked.

The word then was that the original Vega hypertectic aluminum/silcon block was OK 'til a little coolant hit the bore and then it was all over rather quickly. Wouldn't be a prob with aircooled would it? That block was very hard and very strong for it's weight.

Hmm. Get an old Franklin, pull the sleeves, make some pistons, Nikasil the cylinders. Presto, 395 cu. in.

Ron
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