HAYNES combustion 4 cylinder engine model valves

However, a V6 with uneven firing intervals of 90° and 150° shows large torque variations of 185% above and 172% below mean torque. In the case of a four-cylinder engine, the peaks are approximately 270% above mean torque and 210% below mean torque, with 100% negative torque being delivered between strokes. In a six-cylinder engine with an even firing interval, the next piston starts its power stroke 60° before the previous one finishes, which results in smoother delivery of power to the flywheel.Ĭomparing engines on a dynamometer, a V6 engine shows instantaneous torque peaks of 154% above mean torque and valleys of 139% below mean torque, with a small amount of negative torque (engine torque reversals) between power strokes. Each piston comes to a complete stop and reverses direction before the next one starts its power stroke, which results in a gap between power strokes, especially at lower engine speeds (RPM). In a four-cylinder, four-stroke engine, only one piston is on a power stroke at any given time. Six-cylinder designs have less pulsation in the power delivery than four-cylinder engines, due to the overlap in the power strokes of the six-cylinder engine. To reduce the vibrations caused by this imbalance, most V6 engines use a harmonic damper on the crankshaft and/or a counter-rotating balance shaft. Straight-six engines and flat-six engines do not experience this imbalance. The displacement of modern V6 engines is typically between 2.5 to 4.0 L (153 to 244 cu in), though larger and smaller examples have been produced, such as the 1.8 L (110 cu in) Mazda V6 used in the 1991–1998 Mazda MX-3, or the 1.6 L (98 cu in) Mitsubishi V6 engine used in the 1992–1998 Mirage/ Lancer, while the largest V6 built was the 7.8 L (476 cu in) GMC V6 used in the 1962 GMC C/K series 6500.Īll V6 engines with even firing spacing-regardless of the V-angle between the cylinder banks-are subject to a primary imbalance caused by each bank consisting of an inline-three engine, due to the odd number of cylinders in each bank.

Some sports cars like the Porsche 911 use flat-six engines instead of V6 engines, due to their near perfect primary engine balance and lower centre of gravity (which improves the handling).

A downside for luxury cars is that V6 engines produce more vibrations than straight-six engines. Due to their short length, V6 engines are often used as the larger engine option for vehicles which are otherwise produced with inline-four engines, especially in transverse engine vehicles.

HAYNES combustion 4 cylinder engine model valves