Iron VS. Aluminum

Iron VS. Aluminum
When pushed to the extreme, it's pretty safe to say that the only advantage of an aluminum block over an iron block is weight savings. "Keeping all else equal, we take a 30-45hp hit in our aluminum motors compared to our iron motors." The rate of thermal dissipation is higher, but that only accounts for 10 percent of total power loss. "The bigger issue is that cylinder-wall retention is impossible to maintain. With aluminum, the cylinder walls can move around, ring seal is terrible, and leakdown is always worse." However, if a thicker cylinder wall is used in the block, the trade-off wouldn't be as bad and the weight savings could make up for the difference in power. We compensate for this by putting bigger cams in aluminum motors and by winding them out a little higher.