You would need to be some sort of mechanical or engineering background information, however, to determine if party B's mechanical system is different enough from party A's mechanical system to rule on some sort of patent issue between the 2 parties. To one person, an engine is an engine. They don't care if it's petrol, diesel or rocket fuel. It's the loud bit that makes vehicles move.
Someone determining whether or not the latest engine by VW (for example) is too similar to an engine previously made by Alfa Romeo is going to need to know more than "an engine is the loud bit that makes vehicles move" - somebody is going to have to explain the details behind the mechanics. Based on this information, they might decide that the engine as a whole isn't a rip-off, but maybe the odd way the valves are set up is suspiciously similar. It would be unfair to make a judgement without the extra technical knowledge.