Straight-six engine
Due to its well-balanced configuration, the straight-six can be scaled up to substantial sizes for heavy trucks, locomotives, industrial and marine use.
The primary balance is due to the front and rear trio of cylinders moving in pairs (albeit 360° out of phase), thus canceling out the rocking motion present in a straight-three engine.
Still, all of them have a rocking imbalance that may or may not require a balance shaft, depending on the application.
[7] Mercury came to use a configuration that canceled only the primary rocking couple and was run without a balancer.
Still, the balance of kinetic energy exchange between pistons has improved to a residual 6th-order-and-up inertial torque oscillation compared with the four-stroke design being imbalanced at 3rd-order and up.
[9] Straight-six engines increased in popularity in the years after and by 1909, approximately 80 manufacturers were using them (including 62 in the United Kingdom).
An exception to this trend is the German brand BMW, which has always used a straight-six layout for its six-cylinder engines.
This car was replaced by the 1906–1926 Rolls-Royce Silver Ghost, which switched to a flathead (side-valve) design for its straight-six engine.
In 1906, the Standard Six luxury car was introduced, powered by a 20 hp (15 kW; 20 PS) I6 petrol engine.
The 1927 Rover Two-litre luxury car introduced the company's IOE straight-six petrol engine.
[19] The 1930–1936 Wolseley Hornet six lightweight car was powered by a 1.3-1.6 L overhead camshaft straight-six petrol engine.
The Triumph I6 overhead valve straight-six petrol engine was produced from 1960 to 1977 and debuted in the Standard Vanguard Six sports saloon.
The Ford 300 cu in (4.9 L) version of the straight-six engine was built from 1965 until 1996, with notable uses in trucks, SUVs, and vans.
The unrelated Pontiac OHV 6 overhead valve engine was produced in 1964–1965, based on a Chevrolet design.
[22][23][24] Production of the Hudson I6 continued after the 1954 merger forming American Motors Corporation and was eventually replaced by a new Rambler V8 after 1956.
The Slant-6 was released in the Dodge Dart economy car and used in many models until a V6 engine replaced it after 30 years.
[26][27] The final application for the AMC Straight-6 engine was the 2006 Jeep Wrangler (TJ), after which a V6 replaced it.
[31] Also, the Duramax Straight-6 turbocharged diesel engine has been available in several General Motors SUV and light truck models since 2020.
[32] On March 25, 2022, Stellantis announced their new turbocharged straight-six engine, called Hurricane.
[33] Two outputs are available, a standard 400 or 500 hp (298 or 373 kW; 406 or 507 PS) high performance rated at 450 or 475 pound force-feet (610 or 644 N⋅m) of torque.
The turbos on the Hurricane Standard Output deliver a peak boost of 22 psi, while the Hurricane High Output turbos deliver 26 psi of peak boost.
This was replaced by the dual overhead camshaft Toyota FZ engine, produced from 1993 until 2008.
The 1985–2004 Nissan RB engine, used in the Nissan Skyline and several other cars, was produced in single overhead camshaft and dual overhead camshaft configurations until a V6 engine replaced it.
Ford produced straight-six engines for the longest time of any Australian manufacturer.
This was followed in 2002 by the Ford Barra dual overhead camshaft engine in 2002, which was produced in both naturally aspirated and turbocharged versions.
[34] The 1962–1965 Austin Freeway and Wolseley 24/80 large sedans were powered by BMC Australia's Blue Streak overhead valve petrol engine.
[35] This engine was upsized to a 2.6 L displacement in 1973 and used Leyland P76 and the Morris Marina large cars until 1975.
[37] The unrelated road-use Honda CBX was produced from 1978 to 1982 and was powered by a 1,047 cc (63.9 cu in) dual overhead camshaft petrol engine.
[40] The 1979–1989 Kawasaki Z1300 roadster motorcycle was powered by a 1,286 cc (78.5 cu in) dual overhead camshaft petrol engine.
[41] From 2011–present, the BMW K1600 series of touring motorcycles have been powered by a 1,649 cc (100.6 cu in) dual overhead camshaft petrol engine.
