We tried a few Cosworth cams in the Romeo 4-valve aluminum engine. In fact we tried MANY different cams. Some of the Cosworths had lobes that were on individual splines, probably made from powdered metal. Some of the camshafts were hollow. Since there are no pushrods, 14K rpms is possible. The valve train simply uses (roller) cam followers and (stationary) lash adjusters under the cam, so the valve train has very little mass.