Iron Ram heads from Hughes

Fishy, The key to maximum power output is to use all the energy to move the piston. Because iron does not remove heat from the burn as well, it will always make more power when built identically. It keeps the heat where itbelongs. But it's a very small margine, and by identically i mean chamber design, spark plug, valve size, shape and material, etc have to be identical. Not many heads offer that identicality (word?) in both materials. An engine built for aluminum heads that takes into account the chamber heat retention, will make the same power as iron. That's why big $$ engines use chamber coatings with aluminum heads. The car manufacturers use aluminum because it's lighter. No other reason. They also build the rest of the engine around it's use. That's my take anyway...