Overhead Valve

Overhead Valve

An overhead valve (OHV) engine, also informally called pushrod engine or I-head engine, is a type of piston engine that places the camshaft within the cylinder block (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 actuate rocker arms above the cylinder head to actuate the valves. Lifters or tappets are located in the engine block between the camshaft and pushrods. The more modern overhead camshaft (OHC) design (still literally overhead valve) avoids the use of pushrods by putting the camshaft in the cylinder head.

In 1949, Oldsmobile introduced the Rocket V8. It was the first high-compression I-head design, and is the archetype for most modern pushrod engines. General Motors is the world's largest pushrod engine producer, producing both V6 and V8 pushrod engines.

Few pushrod type engines remain in production outside of the United States market. This is in part a result of some countries passing laws to tax engines based on displacement, because displacement is somewhat related to the emissions and fuel efficiency of an automobile. This has given OHC engines a regulatory advantage in those countries, which resulted in few manufacturers wanting to design both OHV and OHC engines.

However, in 2002, Chrysler introduced a new pushrod engine: a 5.7 litre Hemi engine. The new Chrysler Hemi engine presents advanced features such as variable displacement technology and has been a popular option with buyers. The Hemi was on the Ward's 10 Best Engines list for 2003 through 2007. Chrysler also produced the world's first production variable valve OHV engine with independent intake and exhaust phasing. The system is called CamInCam, and was first used in the 600 horsepower (447 kW) SRT-10 engine for the 2008 Dodge Viper.

Read more about Overhead ValveHistory, Advantages, Limitations, 1994 Mercedes/Ilmor Indianapolis 500 Engine

Other articles related to "overhead valve, valve, overhead":

Overhead Valve - 1994 Mercedes/Ilmor Indianapolis 500 Engine - See Also
... Valvetrain Overhead camshaft Cam-in-block Flathead engine. ...
Harley-Davidson XA
... were based on the flathead BMW R71 (1938-1941) versus the overhead valve (OHV) BMW R75 (1941-1946) ... was "dead" as far as the military was concerned for full-blown production, both the side-valve and overhead-valve versions of the XA engine were explored according to Jerry Hatfield in his book "Inside Harley-Dav ... A 45 cu in (740 cc) overhead-valve version XA motor was sent to Detroit Wax Paper for testing as a generator set ...
Straight-eight Engine - Post-war
... time Cadillac also introduced their first overhead valve V8 ... ended production of their signature straight-8 at the end of 1954, replacing it with an overhead valve V8 ... By the end of the 1970s overhead valve V8s powered 80% of automobiles built in the US, and most of the rest had six-cylinder engines ...
Victoria (motorcycle) - 1920–1932
... In 1920 Victoria launched the model KR 1, which has a 494 cc BMW twin-cylinder side-valve flat twin (boxer engine) mounted longitudinally in the motorcycle ... In 1923 Victoria launched its KR 2, an overhead valve (OHV) flat twin producing 9 horsepower (6.7 kW) ... At the same time Victoria also offered the 200 cc side-valve KR 20 and 350 cc overhead valve KR 35 models ...

Famous quotes containing the word overhead:

    What a fog! Plane been buzzin’ around overhead for the last half hour. Must be like trying to find your way through the inside of a cow. I never did see such a country. Even the birds are walkin’.
    Dalton Trumbo (1905–1976)