Andrei, thats exactly what the cooent passage is for to warm up the manifould in cold weather. What year is the Z and is it injected or not ? If you live in other than Cal or Florida and drive the car in winter you most likely wont like performance . Cold start up and warm up will take longer befor the engine will preform without stumbeling. I greatly doubt that you will experience any real positive results with this mod. . If you are attempting to cool the fuel mixture , add a air induction that mounts the air cleaner in front of the radiator. You might get some added performance . Good luck Gary Portland Ore.