volume of tubing vs cylinder displacement

[arydberg]

I spent a lot of time in modifying a 90 degree air compressor as a Stirling engine but it never worked. Now i have come to the conclusion that the physical distance between the cylinders is a problem. Lately I feel if two overhead valve gas engine blocks were placed so the cylinder heads were close to each other then the volumes of tubing going from one to the other would be minimized and could be used for heating or cooling the gas. The 2 crankshafts could be connected with roller chains perhaps bicycle chains and set up for a 90 degree phase difference.

I assume the volume available for tubing is equal to the displacement of each cylinder. Is this true. Does anyone really know?

[Ian S C]

There was one built with a V twin compressor on this forum 2 or 3 years ago. Not much of the original parts were used, new crankshaft, con rods, pistons, cylinder heads. I think it was built as an ALPHA motor, I don't remember how well it worked, but its not the ideal , your probably just as good starting from scratch.
Car engine block I think is not at all suited for conversion to Stirling Engine. Ian S C

[arydberg]

Harbor freight sells a overhead valve gas engine for about $100. The overhead valve is important so there is no space wasted on side valves.

If 2 of these are used all that is needed is 2 cylinder heads fitted with tubing to connect them. I am thinking about building one.

[Ian S C]

Arydberg, I don't know about you, whether you have a machine shop, experience with building working Stirling Engines, or other engineering projects. Your proposals are quite ambitious, even for an experienced engineer.
Might be an idea to introduce yourself in the "I'm new here thread, it's a bit of a thing we have, Daryl/ Boydhouse can see at a glance who the new guys are.

Ian S C

[GP41]

Hi, here I'm:
I'm a newcomer, my suggestion is: let the tubing as they are, and adjust the angle not at 90° but 130°or maybe more.
GP41

[Ian S C]

One thing you don't need is the valve gear of an internal combustion engine, there are no valves in a Stirling Engine. The length of the tubes between the cylinders have little to do with the running of the engine, experiments in UK back in the 1980s showed that tubing up to 6ft long on a small V type GAMMA motor had no noticeable effect on the power of the motor. Ian S C

[staska]

I could disagree on dead volume non importance for engine performance. Going from pure gamma to beta with common swept wolume of only 22% of working volume have added 50% more power.

But, that is more important - alpha engines with only two cylinder is the worst case of forced-to-indicated case of 0.81. Beta or gamma has 0.3.

Ps. where is perfect book written by J. Senft - Mechanical Efficency of heat engines, it really show why most hobby engines does not work at all or produce only fractional power from designed level.