Crossflow cylinder head

Crossflow cylinder head

A crossflow cylinder head is a cylinder head that features the intake and exhaust ports on opposite sides. The gases can be thought to flow across the head. This is in contrast to reverse-flow cylinder head designs that have the ports on the same side.

A crossflow head gives better performance, but the popular explanation put forward for this — that the gases don't have to change direction and hence are moved into and out of the cylinder more efficiently — is a simplification since there is no continuous flow because of valve opening and closing. But since there is overlap between the intake and exhaust profiles there is a point in which both valves are open. At that point the inertia of the exhaust gases leaving the cylinder helps to aspirate the intake gases into the cylinder. The other main reason for a crossflow's performance is that the ports and valves can be larger and its physical separation of the hot exhaust manifold keeps the air in the intake manifold cooler. Most modern engines are of a crossflow design.

"Crossflow" is often used to refer specifically to Ford Motor Company's Kent Crossflow 4-cylinder OHV engine. This unit has been used in cars from the 1960s up to the present day, albeit with the addition of fuel injection and a modern engine management system. The term was also briefly used in the early 1980s in Australia for the revised 4.1 litre inline six-cylinder engine in Ford's Australian large family car, the Falcon. This was in response to the post-1979 fuel crisis where the Falcon was a comparatively fuel-inefficient car compared to its contemporary rivals.

This term is used for engines which have only one intake and one exhaust valve per cylinder; four (or five) valves per cylinder result in engines having superior performance sourced from total port size, rather than the relative location of the ports.

See also

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • crossflow cylinder head — A cylinder head design (especially in an OHC engine) with the inlet manifold on one side and the exhaust manifold on the other side of the head, so that inlet and exhaust valves are arranged on opposite sides of the combustion chamber, giving a… …   Dictionary of automotive terms

  • cylinder head — The detachable metal (aluminum or iron) plate or cap that is bolted to the top of the cylinder block. It is used to cover the tops of the cylinders, in many cases the cylinder head contains the valves, it also forms part of the combustion chamber …   Dictionary of automotive terms

  • Reverse-flow cylinder head — A reverse flow or non crossflow cylinder head is one that locates the intake and exhaust ports on the same side of the engine. The gases can be thought to enter the cylinder head and then change direction in order to exit the head. This is in… …   Wikipedia

  • X-flow cylinder head — See crossflow cylinder head …   Dictionary of automotive terms

  • Crossflow — may refer to: Ford Kent engine Crossflow cylinder head This disambiguation page lists articles associated with the same title. If an internal link led you here, you may wish to change the link to point directly …   Wikipedia

  • head — [1] The upper part of something. [2] A term used to express the increase of energy content in a fluid pumped, expressed in units of energy per unit of mass, usually simply ft (feet). [3] A part of the engine which covers the piston and creates… …   Dictionary of automotive terms

  • crossflow head — A cylinder head with the intake valves) on one side of the combustion chamber and the exhaust valve(s) on the other. Also called T head …   Dictionary of automotive terms

  • T-head — [1] A type of cylinder head in a side valve engine where the valves are either adjacent and parallel or installed on opposite sides of the piston in a configuration resembling a T . [2] A type of screw or bolt head shaped like a T . See T head… …   Dictionary of automotive terms

  • T-head engine — An engine in which the arrangement of the valves on either side of the combustion chamber creates a T configuration. Usually the intake valves are on one side and the exhaust on the other. The modern crossflow cylinder heads are variations on… …   Dictionary of automotive terms

  • Ford Straight-6 engine — Straight 6 Manufacturer Ford Motor Company Production 1941 1996 (US) 1960 present (AUS) 1961 1991 (ARG) …   Wikipedia