The air intake manifold is an integral part of modern internal combustion engines. Currently manufactured in glass fibre reinforced PA66, inquiries have been raised regarding a change of material to glass fibre reinforced PP. A new engine project is the purpose for which this proposed material is evaluated. The thermochemical environment in the air intake system puts high demands on the material. Ageing treatments and tensile testing was conducted on samples of the new material, as well as on the currently used PA66 to evaluate mechanical response of each material to treatments made to simulate the air intake environment. Furthermore, understanding of the chemical setup is lacking and needs to be studied. Experiments was performed to study the chemistry of the intake environment. Results indicated that PP can retain sufficient mechanical rigidity and strength when subjected to parameters made to simulate the air intake. Moreover, results regarding the chemical environment in the air intake system provided limited information.