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DannoXYZ · February 7th, 2022, 01:22 AM

These composite coatings simply do not wear like old cast iron bores. That's why there's no reason to hone them. I've replaced rings & pistons on 2T dirt bikes over 10x with Nikasil bores with no honing needed (NiCom in U.S.). The surfaces are easily 10x stronger than cast-iron. Just look up strengths of nickel-steel alloys, they are tough! Further alloying makes them indestructible really.

Similarly, '80s Porsche water-cooled engines started using Alusil, a hypereutecic alloy first used in Chevy Vega (Reynolds 390). It is made with +21% silicon embedded in aluminium. The cylinder surface is prepped just like iron bores to working size. Then final etching/lapping phase is done at end to remove aluminium from between silicon crystals at surface. This leaves tough silicon cylinder surface with pores to hold oil. Many engines having +200K miles when rebuilt, have no measurable wear on cylinders. Porsche's service manual states to not hone and just replace rings and put back together. Iron-coated pistons are needed to match toughness of these silicon bores.

I actually rebuilt one such engine starting at 250K-miles with just new rings. It lasted 2 racing seasons at double factory boost (+450bhp) with no problems. Only blew headgasket because I got greedy and turned up boost just before start of Open Track Challenge without proper dyno tuning. Tore it apart and replaced headgasket overnight in parking lot of Willow Springs to finish event and it went another 2-years without any problems. That's when I rebuilt it... again no wear could be measured; so just valve job; rings and and bearings... good as new!

Honda's silicon-carbide MMC cylinders are even tougher! Not even possible to hone them as surface is tougher than any boring-bar or honing stone available. These engines have easily gone 400K mile before needing rebuild. Again, no measurable wear on cylinders, so just new rings and bearings are needed.

https://www.researchgate.net/publica...e_industry#pf3
https://www.researchgate.net/publica...ication_detail
https://citeseerx.ist.psu.edu/viewdo...=rep1&type=pdf
http://lnengineering.com/files/2019-...er-Systems.pdf

February 7th, 2022, 01:22 AM	#39
DannoXYZ ninjette.org certified postwhore Name: AKA JacRyann Location: Mesa, AZ Join Date: Dec 2011 Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M ST1300PA Valkyrie-F6C Posts: A lot. MOTY - 2018, MOTM - Nov '17	These composite coatings simply do not wear like old cast iron bores. That's why there's no reason to hone them. I've replaced rings & pistons on 2T dirt bikes over 10x with Nikasil bores with no honing needed (NiCom in U.S.). The surfaces are easily 10x stronger than cast-iron. Just look up strengths of nickel-steel alloys, they are tough! Further alloying makes them indestructible really. Similarly, '80s Porsche water-cooled engines started using Alusil, a hypereutecic alloy first used in Chevy Vega (Reynolds 390). It is made with +21% silicon embedded in aluminium. The cylinder surface is prepped just like iron bores to working size. Then final etching/lapping phase is done at end to remove aluminium from between silicon crystals at surface. This leaves tough silicon cylinder surface with pores to hold oil. Many engines having +200K miles when rebuilt, have no measurable wear on cylinders. Porsche's service manual states to not hone and just replace rings and put back together. Iron-coated pistons are needed to match toughness of these silicon bores. I actually rebuilt one such engine starting at 250K-miles with just new rings. It lasted 2 racing seasons at double factory boost (+450bhp) with no problems. Only blew headgasket because I got greedy and turned up boost just before start of Open Track Challenge without proper dyno tuning. Tore it apart and replaced headgasket overnight in parking lot of Willow Springs to finish event and it went another 2-years without any problems. That's when I rebuilt it... again no wear could be measured; so just valve job; rings and and bearings... good as new! Honda's silicon-carbide MMC cylinders are even tougher! Not even possible to hone them as surface is tougher than any boring-bar or honing stone available. These engines have easily gone 400K mile before needing rebuild. Again, no measurable wear on cylinders, so just new rings and bearings are needed. https://www.researchgate.net/publica...e_industry#pf3 https://www.researchgate.net/publica...ication_detail https://citeseerx.ist.psu.edu/viewdo...=rep1&type=pdf http://lnengineering.com/files/2019-...er-Systems.pdf Last futzed with by DannoXYZ; February 7th, 2022 at 08:08 AM.