An exhaust manifold collects the exhaust gases from multiple cylinders into one single pipe. Exhaust manifolds are generally made up of cast iron or stainless steel which collect engine exhaust gas from multiple cylinders and deliver it to the exhaust pipe. Individual exhaust headpipes for each cylinder are commonly collected into a one tube called header. The design of an exhaust manifold which is studied and experimented in the paper depends on pressure drop and volumetric flow rate. Various geometrical types of exhaust manifold had been studied using experimental methods as well as numerical methods(CFD). This paper reveals about severe heat cycles conditions, the exhaust manifold of an engine can have problems of crack and extensive plastic deformations, the finite element method is being applied to predict thermal stress and deformations in manifold area.