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Motorcycles account for almost 80% of private vehicles in Indonesia, with an annual growth rate of 12% per year. This paper aims to investigate the emission profiles of CO2, CO, HC and NOx based on typical fuel and motorcycle types in Indonesia. Questionnaire surveys were undertaken to gather fuel type, engine technology and capacity representing the motorcycle population in Bandung City, Indonesia. Emissions were measured based on six-speed variations on a chassis dynamometer. Questionnaire surveys from 290 respondent show that EURO II and EURO III technology with engine capacity less than 150cc is the most utilized type of motorcycle in Bandung. Most of the users’ chose RON 90 and RON 92 gasoline. Based on the results, four groups of 5 motorcycle of EUROII-RON90, EUROII-RON92, EUROIII-RON90, and EUROIII-RON92 were tested. Emission data showed that the higher the speed, the lower the emission, except for CO and NOx which have a different pattern.

Due to the depletion of world petroleum resource and the increasing of exhaust gas emission, further efforts on the research to seek for new energy and reduce the exhaust gas emission have been made to fulfill the huge energy demands today. From this aspect, Biofuel has been found as one of the most promising fuel for its energy contribution and polluted exhaust gas emission reduction. From various feedstock, Jatropha Curcas oil (JO) is motivated to use in diesel engine because of its several advantages such as non-edible oil, available in tropical areas, biodegradable and low cost compared to other biofuels. From the long-term durability test, using JO10 still has some problems caused by the high phosphor content in the fuel [1]. This presence causes much effect on injector coking and finally, piston and liner erosion, ring sticking. Further improvement is needed to remove the phosphor from the fuel (Degummed fuel).

The Biodiesel is an alternative diesel fuel derived from vegetable oil or animal fat by chemical reaction termed transesterification. Comparing with diesel fuel, biodiesel has many advantage such as: It can supply new energy source; It is renewable fuel and can reduce net CO2 cycle; It helps reduce exhaust gas emission to meet the future legislation due to oxygen content and high cetane number; It decrease impact to the environment due to high biodegradable. Southeast Asia, located in tropical area, has potential source to produce biodiesel. In Indonesia, Physic Nut oil now is considered as one of the most advantage source to make biodiesel due to it is non-edible and in-commercially exploited. The using of biodiesel from Physic Nut oil on diesel engine can supply as a new energy source replaced for diesel fuel and substituted palm oil as biodiesel raw material during the periods of high food sector demand.

Cycle-to-cycle changes in diesel exhaust gas emissions were investigated under two transient operation patterns: One, “an interval step decreasing and increasing load”, where the fuel amount is rapidly decreased from high to low loads, and after an interval, Δtint the fuel amount is abruptly returned to the initial level. The other is “a ramp increasing load”, where the fuel amount is increased gradually. Except just after the step increase in fuel amounts, the THC emissions were almost completely determined by the piston wall temperature and fuel amount. However, the THC concentrations immediately after the step increase in fuel amounts were much higher than the value of the corresponding steady state operation with the same piston wall temperature. This overshoot concentration, ΔTHC, was almost constant at different intervals, Δtint and it can be suppressed by ramp increased loading.

Diesel combustion and exhaust gas emissions under transient operation (when fuel amounts abruptly increased) were investigated under a wide range of operating conditions with a newly developed gas sampling system. The relation between gas emissions and piston wall temperatures was also investigated. The results indicated that after the start of acceleration NOx, THC and smoke showed transient behaviors before reaching the steady state condition. Of the three gases, THC was most affected by piston wall temperature; its concentration decreased as the wall temperature increased throughout the acceleration except immediately after the start of acceleration. The number of cycles, at which gas concentrations reach the steady-state value after the start of acceleration, were about 1.2 times the cycle constant of the piston wall temperature for THC, and 2.3 times for smoke.