MARS engines are not Lister clones. Mars engines are bigger, heavier and more robust than Lister engines. When you listen to a Lister and then to a MARS you will agree. This engine has a 3 " diameter crankshaft and not one component is interchangeable with a Lister.

MARS engines were commonly used in industrial situations such as factories to power line shafts which powered a number of machines, a task Lister engines had some trouble with apparently with their crankshafts twisting under the load on start up, and why this company made the Mars Diesel.

5 HP MARS engines were painted Maroon colour as standard from the factory although there are variations of colour in existence. 8 HP engines were a different colour.