Studi pengaruh volume ruang bakar pada kinerja sepeda motor empat langkah sebagai aktivitas dalam project-based learning termodinamika di sekolah menengah kejuruan

Study of the Effect of Combustion Chamber Volume on Four-Step Motorcycle Performance as an Activity in Thermodynamics Project Based Learning in Vocational High Schools. Thermodynamics is rarely taught with practical activities. The research was conducted to investigate the performance of motorized vehicle engines related to fuel efficiency. Machine performance can be taught with a Project Based Learning approach. Modification of the volume of the combustion chamber on the cylinder head is done to change engine performance. The pressure and power possessed by a vehicle engine are the main components of engine performance. The results of data analysis on the modification of the combustion chamber obtained the diameter before being modified from 50 mm to 54 mm, TMA from 49.5 mm to 54 mm, TMB from 5.5 mm to 3.5 mm, compression ratio from 9: 1 to 15: 1. This causes fuel consumption from 86.5 ml to 89.5 ml at 6000 rpm, from 62.33 ml to 64.166 ml at 4000 rpm, from 48.166 ml to 50 ml at 2000. This modification increases energy. The heat entering the system is 0.1 kJ, the thermal efficiency increases by 0.1%, the net work increases by 0.4 kJ, and the average effective pressure increases by 0.3 N/cm 2 .