The paper describes the theoretical and experimental development of the intake manifold for a 12-liter, 6-cylinder supercharged Diesel engine with intercooling. The objective has been to obtain a torque diagram optimum for traction, i.e. with the maximum torque at a low engine rpm without penalizing the peak power, in addition the design has to keep a reduced fuel consumption and low smoke level. To meet these requirements, the solution adopted has been to obtain the cylinder filling by means of the combined effect of the turbocharger and the geometry of the intake manifold. The design of the manifold is based on the use of lengths and diameters for the pipes appropriate to obtain the desired volumetric efficiency diagrams, avoiding the use of intermediate reservoires. This solution has some advantages for the case of big automotive engines with intercooling, since usually long pipe lengths among turbocharger, intercooler and cylinders are needed.