Power: Because each cylinder on a radial engine has its own head, it is impractical to use a multivalve valvetrain on a radial engine. Therefore, almost all radial engines use a two valve pushrod-type valvetrain which may result in less power for a given displacement than multi-valve inline engines. The limitations of the poppet valve were largely overcome by the development of the sleeve valve, but at the cost of increased complexity, maintenance costs and reduced reliability.[citation needed]