Subaru

H4 engine

H4 engine
Written by Editorial Staff

This engine is the face of Subaru cars.  Subaru Company uses opposed ones which are one of the internal combustion engine layouts. The pistons are installed at 180° and move horizontally to and from each other. Two adjacent pistons are always in the same position, e.g. at the upper dead centre.

The movement of the pistons in the engine can be compared with a boxer fight, hence another name for an opposed engine is a boxer. A special feature of the design is the installation of each piston and connecting rod on a separate connecting rod journal. Opposed ones always have an even number of cylinders (2, 4, 6, 8, 10, 12), the most common are four- and six-cylinder ones. The undeniable advantages of an opposed engine are its low center of gravity, minimal vibration during operation and a high level of safety in a frontal collision. Down shifted center of gravity provides better stability and handling of the vehicle. The low-mounted engine is on the same axis as the transmission, thus achieving a more efficient power transmission.

What engine does Subaru use?

History of Subaru four-cylinder engines has three generations: EA series (1966-1994); EJ series (1989-1998, crankshaft on 5 main bearings, 1999-2010, crankshaft on three main bearings); FB series (since 2010). Six-cylinder Boxers went into production later – ER series (1987-1991), EG series (1992-1997), EZ series (since 1999).

The opposed engine is almost completely free of vibration. Mutually coordinated motion of adjacent pistons ensures smooth operation. The mass balance in the opposed engine allows the crankshaft to be mounted on three main bearings (instead of the usual five), which significantly reduces the length and its weight.

Opposed motor meets passive safety requirements to a greater extent. In a head-on collision, the engine goes down under the vehicle and thus saves the lives of passengers in the passenger compartment.

Unfortunately, it has its disadvantages. The most serious is the high labor intensity of repair work associated with the peculiarity of the engine design. It is noted in some sources that the horizontal movement of the piston leads to uneven wear of the cylinder liner and, as a result, increased oil consumption.

They are currently being developed and installed by Subaru and Porsche. Earlier, it was possible to see an opposed engine on Alfa Romeo, Citroen, Chevrolet, Honda, Lancia, Toyota, Volkswagen and even Ferrari cars.

What is an h6 engine?

Inline six-cylinder engine pistons rotate the common crankshaft. In theory, the four-stroke six-cylinder one is fully balanced, as the inertia forces of the different cylinders compensate each other. In addition, in contrast with the inline four-cylinder one, the inertia forces of the second order are also mutually compensated. As a result, the six-cylinder inline engines are simple in construction and provide a high degree of smooth running. Again, the theory is that the mutual compensation of all forces is similar to that of the V12, which is two angled six-cylinder engines with a single crankshaft.

The V-shaped six-cylinder engine has a scheme with two rows of cylinders, three in a row, and a common crankshaft applied. The cylinders are arranged at an angle to each other, which is why the letter V appeared in the name.

They appeared on the Italian model Lancia Aurelia in 1950, and due to its compact size quickly gained popularity, especially during the period of mass transition to the transverse arrangement. The V6 was not balanced, but soothing shafts were not used – the vibration problem was solved by counterweights on the crankshaft.

What is the difference between 2.0 and 2.5 liter engine?

The power of a conventional engine (non-turbated and not boosted) depends directly on its working volume. It has two volume values: fiscal and real. Fiscal volume is the value from which the tax is calculated, it always has a “round” value and is indicated on the decorative nameplate of the body, in the name of the model.

The real volume is always smaller than the fiscal volume, as rounding goes up in order to increase the tax amount. So, an engine declared to be 2.5 liter can actually have 2,486 cc, etc.

The main difference between the two is their power, 2.5. liter engine has more horsepower than a 2.0 one.

Does Subaru have a turbo engine?

In all markets except North America, the EJ20H (183 and 190 kW), the EJ20R (205 kW) was equipped with a sequential twin-turbo system and had a characteristic failure in torque during the transition from single to twin-turbo, which was “cured” in the EJ206 (190kW) and EJ208 (205kW), put on the fourth generation of Legacy.

In 1993, there was a significant event that marked a new era in the development of the brand. The Subaru range included the Impreza WRX model (then they were called GT or Turbo, depending on the region of sales) with a 240 hp 2-liter turbo engine, which was also available on the Legacy, but there its power did not exceed 217 “horses”.

A year later, the engineers slightly increased the torque of this unit by 6 hp (although the maximum torque has decreased from 304 to 279 Nm). At the very beginning of 1994, Subaru presented a model WRX STi with EJ20 under the hood, 250 hp and torque of 309 Nm, which was as close as possible to the rally version of Impreza, which replaced Legacy at the World Championships since 1993.

Since then, the WRX and WRX STi have been iconic Subaru modifications and a favourite tuning spot around the world. Interestingly, in the U.S. 2-liter 227 hp WRX appeared only in 2002, and WRX STi – in mid-2003 with 2.5-liter engines of the same power.

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