The use of diesel engines has been increased in the field of transport sector and agriculture due to their high power output and fuel economy. Though the concept of bio-fuel is not a new one, no vehicle is running on road in India. The selection of oil for biodiesel production and stringent emission norms are being the important factors. On the other hand the modern engine technology has to address the challenges of high power output, fuel economy, control of peak cylinder pressure and cold

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... t ability against the fixed compression ratio diesel engines when fuelled with both conventional and bio-fuels. The above mentioned challenges can be addressed by employing the non-edible oils along with the variable compression ratio technology. Different kinds of edible/nonedible oils and their methyl/ethyl esters have been tested in C.I. engines with fixed compression ratio and few of them with variable compression ratio (VCR) also. However, Nicotiana Tabacum L. Seed Oil (NTSOME) has not been tested in VCR diesel engines, yet. Tobacco seed oil is nonedible oil and it is the by-product of tobacco leaves process. In this direction, the concern of the present experimental investigation is the assessment of NTSOME as an alternative fuel in a VCR diesel engine. The use of NTSOME in a VCR engine at higher compression ratio results in shorter ignition delay, smaller rate of pressure rise, higher heat release rate and insignificant decrease in mass fraction burnt when compared to that of diesel operation. At high compression ratio, the NTSOME was found to exhibit maximum thermal efficiency. Also, the results show that there is significant reduction in NOx and smoke compared to diesel fuel.