Although a wedge-head design offers simplified valve actuation, it usually does so by placing the valves side by side within the chamber, with parallel stem axes. This can restrict the flow of the intake and exhaust into and out of the chamber by limiting the diameters of valve heads to total no more than the bore of the cylinder in a two valve per cylinder arrangement. With a hemispherical chamber with splayed valve stem angle, this limitation is increased by the angle, making the total valve diameter size possible to exceed the bore size within an overhead valve configuration. See IOE engine for another method.