Vertical Vs Horizontal Engines

Horizontal Engine

Most of you would have seen vertical and horizontal engines on bikes. Many among you would have wondered about the reason behind  a particular orientation. People generally have misconception about the topic. With this post we will compare both types of engines depending upon different parameters.

Power

Most of the people believe that the vertical engines are more powerful. But this is a pure misconception. The reason people give for higher power is that the earth's gravity support the downward movement of of piston and hence adds up to the power. But don't forget that the same gravitation opposes the the piston's motion when the piston moves upwards. Hence the total effect of gravitation remains negligible. It means the effect of gravitation remains same irrespective of orientation of engine.

Stability

The horizontal engines have lower center of gravity as compared to the vertical engines. The lower center of gravity provides more stability to horizontal engine vehicles. Also in horizontal engines piston reciprocate in the same direction as that of the vehicle motion. Hence those vehicles experience less vibrations as compared to vertical engines.

Space 

Space is a very important factor in arrangement of engines. The bigger engines generally have fuel pumps and cooling systems which makes them bulky and hence they can not be accommodated properly inside the frame horizontally. The lower cc capacity engines for eg. 100cc engines are smaller in size and hence can be easily mounted horizontally on frame. The horizontal fitment of engine provides good space below the fuel tank and hence utility box can be fitted easily.

Wear and tear

In horizontal engines, piston always rests on one side of cylinder. This increases the chances of wear and tear of piston rings and the cylinder wall on downward side. The piston in vertical engines remain straight and do not rest upon any specific side, hence it do not cause wear and tear on any specific side. 

Cooling

Vertical Engine

The horizontal engines are better aligned with the air flow direction and hence get cooled easily. The most of the parts of the horizontal engines are exposed to the air this adds up to the cooling by air convection. On other hand the vertical engines are not completely exposed to the moving air that's why they have poor chances to be cooled by air.

Best orientation

In order to provide best orientation to engine we must look at the pros. and cons. of both orientations. It is clear that horizontal engines are more stable since they lower the center of gravity of motorcycle, and vertical arrangement is used to accommodate large size engines. The best possible arrangement would be of inclined orientation. Inclining the engine with vertical will lower the centre of gravity which will ultimately provide stability to the vehicle. The inclined engines are also easily accommodated inside the frame and their exposed area to flowing air also increases a bit. Hence most of the higher cc (capacity) engines are fitted on frame in inclined position.