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Cylinder nitriding
Does anybody have any ideas about cast iron cylinder nitriding for wear resistance? I know it is used for cranks and cams for sliding wear improvement, and some engine manufacturers use nitriding for cylinder bores as well. Anyone ever nitrided a set of Porsche cast cylinders, or know why one shouldn't do so?
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Stephen GruppeB #906 1970 911T |
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03-07-2006, 01:27 PM
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I don't think one can nitride cast iron. The heat treatment is for alloy steel.
Cams are also usually cast iron. Some aftermarket cams have lobes that are built up with an alloy via weld depositing. I believe cast iron is hardened by induction or flame hardening. Camgrinder and others can/should correct me. Cast iron cylinders used to be chrome plated for added wear resistance. Not sure anybody is doing that nowadays. Perhaps your best alternative is to go with a compatible set of rings (probably also cast iron), good break-in procedure and scheduled oil changes. Sherwood |
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03-07-2006, 08:34 PM
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I nitride some cast iron cams. 944 and 928 cams and some others.
These cams had a "tennifer" treatment done at the factory which is sometimes removed by grinding. Nitriding restores the hardness. This process also stress relieves the cam. I would think a finished cylinder would be out of round after nitriding.
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John Dougherty Dougherty Racing Cams |
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03-07-2006, 08:58 PM
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"I don't think one can nitride cast iron. The heat treatment is for alloy steel. "
That's what I though. But, according to Northeast Coating Tech, they can plasma nitride cast iron. I was wondering whether or not it would adversely affect the rings if the surface of the bore was that hard. Then again, Nickasil is pretty hard. Are the same type of rings used for Nickasil as for cast iron?
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Stephen GruppeB #906 1970 911T |
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03-07-2006, 08:59 PM
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Just found this now. Lycoming nitrides their cylinders for aircraft engines after final machining. They claim no dimensional change. Still, I think one would have to be careful, as the traditional nitriding process requires the parts to be at least 500 C. Plasma nitriding is supposed to be less.
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Stephen GruppeB #906 1970 911T |
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03-07-2006, 09:03 PM
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Interesting article on nitriding.
http://www.nitrex.com/english/technologies_extra.htm#nitre
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John Dougherty Dougherty Racing Cams |
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03-07-2006, 09:12 PM
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