Hello Tom,
                Some power measurements have been taken on my 4 DA 800 engine. 
35 Watts at 350 rpm.  Very disappointing from a 800cc engine but not unexpected.
There is not enough heat transfer area plus other wrong things.  I am planning
to add fins outside the heaters and folded (diagonally cut) brass wire mesh
inside.   I have looked at the fast track charts but can't seem to fit my engine
there.  It can only tolerate up to 3 atmospheres pressurization and the charts
call for much more than that.  There are some good points though.  The new
burner is lighter and burns well but could be cranked up a bit.  The seals are
good, however when cold, one cylinder is better than the other three making
starting difficult.  It is certainly not self starting.
   When hot and running well the engine is very smooth up to 400 revs and down to
60 or so. Above 500 revs some vertical vibration starts. The Pin drive works
well but the needle bearings will need to be replaced with ball races. It is
very quiet compared to the Vee Twin Alpha.  The open cylinders of the single
acting Alpha seem to amplify the noise.    The water flow divider works well but
no modifications to the coolers to correct the leaks have been done. I believe
the regenerator volumes are too big and perhaps are too densely filled.  It will
be fairly easy to modify things for trials.  There is probably too much gas
friction so I will increase the cross section area of the heaters first and
perhaps shorten them.  I have put a video of it running on the brake, on You
tube under "Stirling boats"  and then my name (Harry Diers), with other engines
of the Stirling Engine Society.
IT is Spring time now and after a very cold, wet winter we have lots of flowers.
Cheers,   Harry.

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