God i hope you don't believe that. That 2mm thick bit of plastic with next to zero thermal insulation that is just sitting around the pod wont do a single thing. If it drops air intake temperatures by a couple of degrees i would be impressed. Air moves believe it or not and will simply raise the temperature of that bit of plastic until it is the same temperature as the under bonnet temps. However regardless of that, the bit of plastic isn't completely blocking the engine bay heat to the pod, therefore air will simply move around it and the pod will still suck in hot air once again making that shield do nothing.
No disrespect to the OP, people giving things a go to save some money is fantastic, but to think that is actually doing anything is just silly.