Augmentation of turbulent flow heat transfer in a horizontal tube by means of twisted tape inserts with air as the working fluid. In order to reduce excessive pressure drops associated with full width twisted tape inserts, with less corresponding reduction in heat transfer coefficients, width of twisted tape is reduced from 25mm. The drill holes will be provided additionally in the twisted copper tape which allows more air inside than the aluminium pipe, thus the copper tape tends to increases heat transfer rate effectively. Our paper carried out for plain tube with or without twisted tape insert at constant wall heat flux and different mass flow rates. Both heat transfer coefficient and pressure drop are calculated and the results are compared with those of plain tube. It is observed that the enhancement of heat transfer increases as the varying width of the twisted tape compared with plan tube.