"horizontally opposed"

[Wutputt]

Originally Posted by ikon2003 Horizontally Opposed = Boxer = Flat = 180 degree V engine.

That's not entirely true.

In a boxer engine, opposite pistons move in the opposite direction. If one moves outwards, the other one will also move outwards. So if one piston moves to the right, the opposite one moves to the left.

In a 180° V engine, opposite pistons move in the same direction. If one piston moves outwards, the other one will move inwards. So if one moves to the right, the opposite one will also move to the right.