Abstract: Alternative fuels have numerous advantages compared to fossil fuels as they are renewable, biodegradable; provide energy security and foreign exchange savings besides addressing environmental concerns, and socio-economic issues. With regard to stringent emission legislation in the automotive sector and need to save fossil fuel for other developmental and research activities over the coming decades, this research work is directed at developing diesel engine-gasifier integrated systems to operate on renewable fuels such as Honge oil methyl ester [HOME] and Producer gas with specially designed carburetor [1-2, 5-6]. The raw Honge oil was obtained from Honge seeds and then it was subsequently converted into its respective biodiesel i.e., HOME. Further the branches of the Honge tree were used as the biomass feed stock in the downdraft gasifier for the producer gas generation. This work mainly aims at total substitution for fossil fuel by respective renewable fuels and is a step towards energy security and sustainability. The producer gas generated in the downdraft gasifier was then passed through a suitably fabricated carburetor supplying a mixture of producer gas and air at stoichiometric ratio. In this proposed research work different carburetor shapes were identified and developed to maximize the gasifier-engine performance. The developed producer gas carburetor was further analyzed for its mixing performance with a subsequent CFD modeling. The model is a mixing chamber having essential orifices for air and producer gas inlets to generate stoichiometric mixture at near to ambient conditions with required driving pressure differential for the flow. The carburetors were drawn from Y – shape, and with 30, 60, 90⁰ gas entries as well as with parallel gas entry. The CFD -ICEM simulation package was then used to identify better carburetor. From the study it was found that parallel flow gas entry carburetor resulted in better mixing of air and producer gas. The diesel engine developing 3.7 kW was finally operated in dual fuel mode using HOME and producer gas with developed carburetors. The dual fuel engine provided with parallel flow gas entry carburetor showed 4 to 5% increased brake thermal efficiency with reduced smoke, HC and CO emissions. The experimental results were in good agreement with CFD analysis.