Search Results

In order to improve the performance, fuel economy and future emission norms of a reciprocating engine, it is important to reduce the overall engine frictional losses. In this paper, author conducts an experimental study on the friction characteristics due to pumping loss, valve-train system, piston assembly, auxiliaries and transmission for a 110cc, single cylinder 4-stroke gasoline engine using frictional strip-down analysis. This paper deals with the friction performance results for the new concept piston skirt design called the unsymmetrical skirt for least piston skirt friction. Also, parameters like piston profile, oil film thickness optimized for least friction. The piston profile is arrived for optimum contact pattern with least piston slap noise. The modified engine reduced the engine friction by 10% in comparison to the base engine.

In recent past, the two stroke vehicle manufacturers are continuously motivated to develop extreme low emission vehicle for meeting the requirements of emissions regulations. To achieve this emission compliance, manufacturers have developed engines with better induction system, improved ignition timings, increased compression ratio (C.R) and larger after-treatment devices. As an effect of above changes, engine operating temperatures are quite high which reduces the block-piston life. Even though, typical two stroke engines are forced cooled engines, there is a lot of potential for optimizing block cooling to reduce maximum liner temperature and block gradient for enhancing block-piston durability. This paper presents an experimental study of various measures to reduce liner temperature for a two stroke, single cylinder 70 c.c. engine used for two wheeler application.

To improve the performance and durability of two-stroke engines, temperature of the liner/block is an important parameter, which needs to be optimized. In this paper, an attempt is made to measure and investigate the maximum liner temperature of a forced-air-cooled two-stroke engine. The vehicle was tested on both chassis dynamometer and test track to identify the maximum liner temperature during operating conditions. Thermocouple locations were selected at or near the hot spots (TDC & Exhaust port) in the cylinder block. The chassis dynamometer test revealed that the maximum liner temperatures for the test vehicle were near the exhaust port reference position (34 mm from the top face of cylinder block) and TDC reference position (8 mm from the top face of cylinder block near the exhaust port).