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02-12-2010, 02:00 AM

#15

DarZeelon

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RE: OS 46AX On A Header & Pipe

Quote:

ORIGINAL: jay1st

So, with a little bit of porting it might gain 500 RPM.....

Jay,

Your engine has an ABN cylinder sleeve...

Actually, OS call it ABL; but it is ABN, as customary practice dictates it should be done.

There is a flash-coat of copper applied to the sleeve's brass base-metal, so the electro-less nickel coating will bond better to it.
Perhaps it does, but the bond strength is nowhere near that of chromium, in true ABC (or AAC) engines.

So, this ABL coating still relies on the surface continuity of the nickel, for its durability... And if you search this forum, you will find OS' ABL sleeves still peel occasionally.
Perhaps, the likelihood is lower than it was, when 'simple' ABN was used; but sleeve peeling is definitely not unheard of...

If your 'porting' work only entails touching up the crankcase bypasses and the crankshaft, fine.
But if it also includes porting of the ports in the sleeve, you might as well be 'jaywalking'... as you would be compromising your whole engine...[X(]

If surface continuity of the nickel is broken in a port, the sleeve will start peeling from there.

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