Pent Roof Engine

31 hp largest air cooled engine in b s history.

Pent roof engine.

In engine design the penta engine or penta head is an arrangement of the upper portion of the cylinder and valves that is common in engines using four valves per cylinder. Larger valves are possible and the combustion chamber is very small less heat loss then came the pinto and the cvh engine in which at last one cam was raised over the cylinder head but this was still a compromise. New high and low for briggs stratton. In the pent roof design the top of the combustion chamber is angled and the valves are positioned at a 45 degrees slant relative to the center of the cylinder.

427 pent roof valve covers this popular chrome valve cover came on many 427 engines in the 60 s including most 427 and 428 powered cars that included the 427 cobras 7 liter galaxies r code 427 fairlanes and numerous racing vehicles of the day. It is similar in concept to the hemi engine both in design and purpose but a hemispherical cylinder head is limited to only two valves without the use of a. A pent roof combustion chamber has no similarity to five ness or a single faced wedge. Pentastar is dodge s trademark for their pentroof head engine.

The unique pent roof combustion chamber has an inverted v shape with side by side valves and uses domed pistons with a top shape that promotes turbulence. The evolution of pent roof combustion chambers began in the early 1900 s with the first side valve engine that had an l shape combustion chamber and was produced by the ford motor company. Pentroof based in tokyo japan offer complete workshop and tuning services specialising in high performance japanese vehicles. While pent as in pent roof means single sided wedge shape as in a window awning.

It s a narrow v 8 due to the vertical 45 degree angle to the cylinder axis positioning of the 1 875 1 50 inch valves from which it earned its nailhead nickname. Various shapes of combustion chamber have been used such as l head or flathead for side valve engines bathtub hemispherical and wedge for overhead valve engines and pent roof for engines having 3 4 or 5 valves per cylinder. Company expands commercial lineup with new engines at both ends of the spectrum. The side valve lasted about fifty years before being succeeded by the overhead valve engines that were operated by pushrods from an integral camshaft.