The design and development of a new four-stroke two-cylinder diesel engine family of 1.29 litre capacity for off road are discussed. The engine is in naturally aspirated and turbocharged and intercooled versions and rated from 11.9 kW/1500 rpm to 25.7 kW/2500 rpm. The engines were tuned for air and fuel flows, air utilisation, fuel air mixing, performance and emissions at steady state at a development lab and later certified in national labs. The high altitude capability of the TCIC was checked using a model. The engines rated at less than 19 kW satisfy India Generator set and off road norms of India and Europe equivalent to USTier4 standard, and at higher ratings, standard equivalent to US Tier4-interim. In the second part of the paper, the design of coolant and oil pumps, oil cooler for TCIC engine and the piston with steel oil control ring are discussed. The higher loaded TCIC engines use fillet hardened crankshafts of chromium molybdenum steel. The crankcase integrated with the flywheel housing and the timing case at the front, in conjunction with a cast iron sump makes the engine rigid against torsion and bending in an agricultural tractor. The firing order 0°-360° with the two pistons moving in phase allows lower cyclic irregularity and a light flywheel as well as turbocharging. The resultant primary reciprocating inertia force is neutralized by a counter-rotating balancer shaft and the fluctuations in crankcase pressure are taken care by a valve in the breather to avoid oil carry over.