Originally Posted by JAMMINKRAZY

My experiences are that aluminum cools better. I know for a fact, that's why OS switched to aluminum. Atleast that's what they claimed when the AL head speed was first released. I also know that many guys were running standard v-spec heads on thier speeds before the Al head speed was out for just that reason. That was also GRP's reason for going to the big orange aluminum head over the mag ninja head they had developed for the ninja before they were producing thier engines under the GRP name. I don't know the properties of the metal. I just know what myself and others have experienced, which is that magnesium heads don't cool as well as aluminum heads do. Those are just my findings.