COMPARISON OF 2-STROKE AND 4-STROKE ENGINES: Two-stroke engine possesses the following advantages over the four stroke type:
1. Because of its valueless construction, the two-stroke engine is simpler, more compact, lighter and consequently cheaper to manufacture.
2. Due to twice as many power strokes per revolution, compared to the four stroke type, it delivers smoother torque. However, at lower speeds, this may not happen due to poor scavenging which may give rise to 'four stroke' or irregular firing.
3. The pet roil system of lubrication which has to be used in case of 2-stroke engines, is simpler.
- However, the two-stroke engine has got certain disadvantages also.
- The 'scavenging efficiency' of the two stroke engine is poor, it is not possible, it is not possible to completely purge the exhaust gases from the cylinder and fill it completely with the fresh intake mixture. This results in decreases volumetric efficiency.
- There is greater tendency for the deposition of carbon on the exhaust ports, which further reduces the scavenging efficiency. This would mean that it completely with the fresh intake mixture. This results in decreased volumetric efficiency.
- As there is one power stroke in one revolution for the deposition of carbon on the exhaust ports, which further has one power stroke in two revolutions. The cooling is comparatively more difficult. Thus, it has greater tendency to overheat.
- As pet roil system of lubrication is not very efficient and it tends to the four stroke engine which has one power stroke in two revolutions, the cooling is comparatively more difficult. Thus, it has greater tendency to overheat.