Photos of an unusual six stroke vertical gas engine by Dave Bramwell from the MEWS photo archive dating back to a visit in 2010 to the National Model Engineering and Modelling Exhibition in its Harrogate days.
Six strokes are rare, especially in model form. In the single piston designs, the engine captures the heat lost from the four-stroke Otto cycle or Diesel cycle and uses it to drive an additional power and exhaust stroke of the piston in the same cylinder in an attempt to improve fuel efficiency and/or assist with engine cooling. The pistons in this type of six-stroke engine go up and down three times for each injection of fuel.
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