Paul, I've got a quick question: does a head with more valves in it weigh more or less than a similar head with less valves? I could see a case being made for less because of all the head material that isn't there any longer after you factor in the amount of material that is opened up for the ports. Is all that aluminum that is bored out for the port and the valve seat area more, or less material by weight than what would need to be added back in the form of a valve and springs/retainers/rockers or whatever?
Also, how much would a difference in con rod thickness and piston size factor into a weight comparison? I don't know the specs on these two engines off hand, that may not even be an issue in this case if they are the same...
The Z32TT had dual intercoolers, correct? Is the factory plumbing mostly metal, or rubber? I could see two cast iron manifolds, the turbos, and all the associated intercooler accessories weighing 50+ pounds. In the case of a swap, you would take out all the associated airbox plumbing, so would that factor in to the weight comparison, or no?
Besides that, the gigantic throttle body on the Q-45 probably weighs a good 5 or 6 pounds on it's own...(not really that much, I do have one of those handy!)