Kontax KS90 Stirling Engine


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Kontax KS90 "Low temperature" Sterling Engine

These engines are Manufactured by Kontax Engineering in the UK. They are hard to get and (as far as I know) I'm the only retailer in the US carrying Kontax engines. Quantities are extremely limited. 

 What is a Stirling Engine?

Stirling engines convert a small temperature difference into motion. As long as one plate is warmer (about 5°c) than the other then the engine will run. It doesn't matter which plate is warmer, as long as the other is cooler. If you reverse the temperature differential, and cool the plate that was warm, and warm the plate that was cool then the engine will run in reverse. The Stirling engine is named after its inventor, Rev. Robert Stirling, who patented his idea in 1816.

How do they work?

Stirling engines work by cyclically heating and cooling the air inside the main chamber. As the air heats up it expands, and as it cools down it contracts. This expansion and contraction drives a small piston which in turn drives the flywheel. The clever thing about Stirling engines is that the mechanism for cycling the heating and cooling of the air is built into the engine in the form of the displacer, which is driven by the flywheel and moves the air from the warm side to the cool side and back again over and over.


Because Stirling engines have a theoretical 40% greater efficiency than photo-voltaic (PV) panels worldwide energy companies are investigating using them as a way to provide energy in a more sustainable and environmentally friendly way. Such companies use our full range of low temperature engines to demonstrate the principles behind generating electricity using Stirling engines. 


  • Stainless steel screws (except for piller screws)
  • Micron precision Borosilicate glass cylinder and Graphite power piston
  • Low-profile heat insulated chamber pillars
  • Giving flat bottom and good surface contact with heat source
  • Both connecting rods are positively located using low friction PEEK and stainless steel screws
  • All airtight seals are made with high strength precision screw threads and nitrile O rings
  • Ultra low friction demagnetised and de-greased bearings, NO lubrication required
  • Fully CNC machined, giving crisp, clean and tidy edges all over
  • Engine parts ultrasonically cleaned before hand assembly


Dimensions 3.62" x 5"
Weight 9oz.
Materials Stainless Steel, Borosilicate Glass, Graphite, 6061 Aluminum, C360 Brass
Runs on Hot water/coffee/tea or even ice...anything that creates enough temperature gradient
Where it's Made

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