Hay Elvis, this is flying right off the top of my head ... 
 
But, do you remember that heat engine in high school physics lab?
put a bunsen burner to the finned head of this little jobbie and 
it would start to push the piston/flywheel like a steam engine? 
 
Spoze you rigged a big cylindar that got heat from the wood heat 
stove, could you get any worthwhile electric off it?  Lessee, you 
could duct outside 32 degree air into the (non)combustion chamber, 
and there it would get heated to say 500.  Hmmm. that would be 
273 kelvin vs 550 K or with Carno I guess I'd expect it to put 
out 15 PSI with that temp change. 
 
Could you make a piston big enough cheap enough to do anything 
useful with 15 PSI?  If you could lube the rings with moly, I 
think it might work up to 900 F, or 40 PSI if the stove got all 
that hot, which judging by the cherry red, it sometimes does. 
 
At 15, seems like you'd have a 2:1 compression ratio, so a 
short stroke. 
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 * OFFLINE 1.58 * Blinded by the fog of battle in the war of the sexes.
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