Overhead cam (OHC) piston engines place the camshaft above the cylinder heads and drive the valves or lifters directly instead of using pushrods. This arrangement is more complex, and relies on a timing belt or chain, but allows for greater valvetrain flexibility. Currently, engines have used single overhead camshafts (SOHC) or dual overhead camshafts (DOHC), which refers to the number of camshafts per cylinder bank. Components of a typical, four stroke cycle, DOHC piston engine. ... The camshaft is an apparatus used in piston engines to operate poppet valves. ... The cylinder head from a GMC van. ... poppet valve A poppet valve is the type of valve system used in most piston engines, used to seal the intake and exhaust ports. ... For the ionic propulsion device, see Lifter (ionic propulsion device). ... A pushrod engine or overhead valve (OHV) engine is a type of piston engine that places the camshaft below the pistons (usually beside and slightly above the crankshaft in a straight engine or directly above the crankshaft in the V of a V engine) and uses pushrods or rods to... Timing belt A timing belt, timing chain or cam belt is a part of an internal combustion engine that controls the timing of the engines valves. ... Single overhead cam (also SOHC) refers to the internal combustion engine design where one camshaft is located above the valves. ... A double overhead cam (also called a dual overhead cam, DOHC, or twincam) engine is a type of internal combustion engine where the camshafts that operate the intake and exhaust valves are mounted above the cylinders, and where there are separate camshafts for inlet and exhaust valves. ...

Many OHC engines today employ Variable Valve Timing and multiple valves to improve efficiency and power. OHC also allows for greater RPM, though pushrod designs have closed the gap somewhat. Variable valve timing, or VVT, is a generic term for an automobile piston engine technology. ... In automotive engineering, an engine is referred to as multi-valve (or multivalve) when each cylinder has more than two valves. ...

The highest-revving automobile piston-engine currently available from a large-scale manufacturer is a DOHC design found in the Honda S2000 with a 9,000 RPM limit. Most production car engines with an OHC-controlled valvetrain have limits between 6000 and 7000 RPM. Honda achieves this unusually high rev-limit by use of lightweight components and techniques learned from their design of motorcycle engines. The Honda S2000 is a roadster automobile built by Honda. ...

In addition, purpose-built small-volume engines like the Powertec RPA V8 engine from Radical Motorsport can be built to higher specifications than mass-produced engines. The 2.6 L version has a 10,500 RPM limit and there is a de-stroked 2.0 L version planned that is said to have a 12,500 RPM limit. Powertec RPA is the name of a V8 engine developed by Radical Motorsport in Peterborough England. ... The Liberty V8 aircraft engine clearly shows the configuration A V8 engine is a V engine with eight cylinders. ...