With its unique qualities, such as infinite supply, high octane number, and capacity to cut greenhouse gas emissions, alcohol is a viable alternative fuel for SI engines. This review article aims to reveal to readers the effects of alcohol on the performance, combustion behavior, and emission characteristics of SI engines by collecting the outcomes from previous research. This article looks at methanol, ethanol, and butanol fuel qualities. The performance of SI engines with butanol, ethanol, and methanol combined with gasoline is investigated in terms of brake torque, brake power, fuel consumption, thermal efficiency, volumetric efficiency, mean effective pressure, and coefficient of variation under various conditions. Second, in-cylinder pressure, mass fraction burnt, ignition delay, pressure increases, and heat release rates are also used to evaluate the combustion characteristic. Finally, the article discusses pollutant emissions such as CO, CO₂, NO_x, UHC, and exhaust gas temperature. Methanol, ethanol, and butanol mixed with gasoline increased fuel consumption and lowered spark-ignition engines’ thermal efficiency. When alcohol was combined with gasoline, most research found that CO, NO_x, and UHC emissions were reduced due to improved combustion.

The main purpose of fuel booster is to enhance the performance and exhaust emissions reduction of an engine. The aim of this experimental analysis is to investigate the effect of fuel booster addition in the form of a tablet and liquid into diesel fuel on performance exhaust emission of diesel engines. The engine test was conducted under three different load or throttle position of 25%, 50% and 75% at constant engine speed of 1500 rpm. The engine performance is evaluated in terms of brake power, fuel consumption and brake specific fuel consumption (BSFC). While the exhaust gas temperature (EGT), CO, CO₂, NO_x and HC were measured and recorded to study the exhaust emission characteristics of the engine. As a result, an addition of fuel booster slightly improved in term of brake power (BP), fuel consumption and BSFC especially during medium and high load condition. In addition, the performance of TDSI/LUTAH Tablet is considerably better than TDSI/LUTAH liquid and baseline diesel. Furthermore, the formation of CO and HC for TDSI/LUTAH Tablet is reduced up to 11.91% and 3.51% compared to baseline diesel especially during medium and high loads. However, the formation of CO₂ and NO_x for both fuel boosters is slightly higher than baseline diesel. Overall, TDSI/LUTAH Liquid is considered better than TDSI/LUTAH Tablet with better fuel economy and performance.