Search results
Results From The WOW.Com Content Network
A hemispherical head ("hemi-head") gives an efficient combustion chamber with minimal heat loss to the head, and allows for two large valves.However, a hemi-head usually allows no more than two valves per cylinder due to the difficulty in arranging the valve gear for four valves at diverging angles, and these large valves are necessarily heavier than those in a multi-valve engine of similar ...
The Hemi-6 is a pushrod O.H.V. (overhead valve engine), with combustion chambers comprising about 35% of the top of the globe. This creates what is known as a low hemispherical shaped chamber. In this way, the "Hemi" moniker was used for the same kind of marketing cachet as Chrysler's 1950s-1970s Hemi V8 engines.
In return, hemi head engines tend to have complex valve trains, are expensive to build, and both larger and heavier than conventional designs. A hemispherical combustion chamber is an efficient shape, with an excellent surface-to-volume ratio, minimal heat loss to the cylinder head, [clarify] and room for two large valves.
The V family engine was used in the prestigious Toyota Century. Toyota had worked with Yamaha to produce the first Japanese full aluminum alloy block engine. The V family is often referred to as the "Toyota Hemi" [citation needed] as the engine features a cylinder head design with approximately hemispherical combustion chambers.
The engine's name is an acronym for either Compound Valve-angle Hemispherical or Canted Valve Hemispherical, where "Hemispherical" describes the shape of the combustion chamber. [ 1 ] [ 2 ] The CVH was introduced in 1980 in the third generation European Escort and in 1981 in the first generation North American Escort .
The cylinder head has four hemispherical combustion chambers, each with two valves having an included angle of slightly over 73°, with the exhaust valves being inclined from the horizontal about 4° more than the intakes. The valves are made of nimonic steel, and have double valve springs. The camshafts are hollow, and run in five bearings each.
The Alfa Romeo Twin Cam engine debuted in the 1954 Giulietta. The engine featured: An aluminium alloy engine block with cast iron "wet" cylinder liners; An aluminium alloy cylinder head with hemispherical combustion chambers. A forged steel crankshaft running in five main bearings; Double overhead camshafts driven by a double row timing chain
All T engines utilize a timing chain and have a cast iron block with an alloy cylinder head with hardened valve seats and a hemispherical combustion chamber design . All T engines are carburetted except those with electronic fuel injection, "E" designation. All T engines use a 2 valve OHV design except those with a DOHC performance head, "G ...