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Hi.

About the dead space in heater tubes, how does it affect on engines
efficiency, or is it so much more important to get big tempereature
difference than get rid of some extra dead space? Some simple
calculations would be great...

I assume you are asking about the space in the Heated Displacer Cylinder.
The end clearances at the end of stroke of the Displace should be as small as practical and the side clearances should be close to minimize dead space, but not so much as to impede air flow in the system.
Reading Ivo Kolin's "Isothermal Stirling Cycle Engine", 1983 would provide you with more information.

Sorry about my bad english.

I ment those heat exchanger tubes outside hot cylinder, used specially in alpha -type engines.

There would be a trade off of some kind. The objective of any heat engine is to supply as much energy as possible at the high temp., extract as much useful work from that energy and reject as little as possible at the low temperature. Keep in mind that the total energy IN must equal the total of the WORK and energy OUT ( Q1 = W + Q2 ).

An acquaintenance mentiond, OK, I bit the bullet and ordered Dr. K. Hirata's book with the attached CD. it is 4600Yen and the local japanese bookstore said it would be 57.20 dollars and take three weeks. The title translates as "Stirling Engine Theory and Design". This may or may not be a valuable publication. There isn't much in print on the design of power producing Stirling engines.

Hi Kumma

Look at:

About the Efficiency of the Regenerator in the Stirling Engine and the Function of the Volume Ratio V max / V min:
http://home.germany.net/101-276996/etatherm.htm