First, nice work. As I mentioned in your
Side fender vents "I very much appreciated the thought, the planning and the effort that went into this modification". But I have to say I wouldn't do this to my car. And as I said in that thread, it's your car so what makes you happy.
Second, you mentioned this was done to draw off hot air from the engine bay. Were you having an overheating issue? Was there a specific reason for this mod? I am asking this because most engines have a specific heat range they operate best within. I have no idea, don't know what that temp range might be for the 1.4L Turbo in the 124 Spider but I have to presume the engineers that designed both our car and the engine within kew what that heat range is and decided at some point the situation lent itself to proficient overall operation of the package. I think this can best be shown and attested to by the number of owners/forum members who have not had, not posted about overheating problems/issues. So my thought is, unless you were having specific overheating issues then why? Why does this heat need to vented off? It would seem that if you're pulling heat off/away from the engine through these newly installed vents then the system, by managing the engine coolant thermostat, is only going to compensate and work to maintain the desired/designed operating heat range.