on 5/4/02 11:57 AM, John Rodgers at j_rodgers@CHARTER.NET wrote:

> Frank Grunthaners comments regarding breakin and synthetic oils, were
> very instructional. It raises a question.
>
> In the pursuit of performance for our beloved boxes (not speed in this
> case - just longevity with minimal maintenance) many different routes
> have been traveled. Increasing wheel diameter so reduce highway cruise
> RPM.......changing drive ratios in the tranny so as to avoid
> inappropriate engine rpms yet still avoid being a traffic obstacle on
> the freeway ........... rebuilding engines with balanced cranks, ceramic
> coated piston skirts, bigger valves, etc, etc, etc. ...... all to add
> long life with minimum maintenance.
>
> Now as it happens, in the general aviation industry, piston engine
> cylinders are removable as they are in the VW aircooled and WBX
> engine.During an overhaul aircraft cylinders are often bored to oversize
> bring  the cylinder back into round, and  then cromeplated to bring the
> cylinder barrel back to standard diameter. Aluminum pistons are the
> mated with grey-iron rings which are wear to a magnificent match with
> the crosshatching in the chrome in the cylinder barrel. The chrome
> crosshatching will hold oil and help in lubrication of the rings after
> breakin. The chrome plated cylinders stand up to wear extremely well,
> much better than steel.
>
> My question is, "has this been done with the small automotive engines
> that use replaceble cylinders? Would it be a practical thing to do? Why
> do it? Why not?
>

Because it is expensive. Aviation engines cost alot more, like $20,000+ for
a rebuilt, and thats for your basic aircooled flat four. Part of that is
because of liability issues but not all of it.