In a message dated 2/20/03 8:28:44 PM, kelphoto@HIGHSPEEDPLUS.COM writes:

<< #1 At 1000 feet per minute of piston travel, or 4000 RPM  the rings on
the piston can begin to vibrate. or resonate.  The wear would be to
pound out the groove the keeps the ring in its place on the piston.
 There is some latitude, depending on the type of rings and cylinder
combination, but as you mentioned the VW green range is up to 4000 RPM.
 The hashed green range, would mean to me, an ex military pilot, a
transitent range to used briefly, say passing, but not a "cruise".

#2  The  other high rpm issue is the crankshaft.  Whether 1.9 or 2.1
WBX, there seems to be a concern of  wear on the center crankshaft
bearing surface.  This wear is attributed to the crankshaft flexing in
the middle, ends stay put. The effect is to elongater the center bearing. >>

Mark,

While I have no opinion about the waterboxer engine technology as I have
never encountered one intimately, I would caution list members the neither of
these observations is true for more modern engines line the in-line VW 4's or
the Subaru waterboxer implementations. As I have discussed at length in the
archives, these engines have been competently designed for continuous
operation at high load to above 6000 rpm. I routinely spin my system to 6500
rpm and done so for tens of hours at a stretch (time out for fueling,
acceleration and deceleration to and fro the gas station and  external
excrement receptacle). Compression tests, measured power levels and oil
analyses indicate that the onset of disaster is still comfortably in the
future.

Frank Grunthaner