Subaru EN engine

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The EN series engine is used for kei cars sold by Subaru in Japan. It is a four-cylinder, four-cycle engine introduced in 1988 as a replacement for the EK23 that was used in the Subaru Rex. While other manufacturers adopted a three-cylinder engine, the Subaru-EN is a four-cylinder. The EN05 547 cc four-cylinder engine block and the cylinder were based on the EK23. Subaru also did make a three-cylinder engine, called the Subaru EF engine which was used in the Subaru Justy, but the larger EF engine is no longer in production.

The following year, 1989, the Japanese Ministry of Transport revised the standards for kei cars. This resulted in the new 660 cc class series of four-cylinder engines, and the EN05 had its stroke increased to produce the EN07. The increased stroke helped make up for the lack of low-speed torque, a weakness of the other four-cylinder 660 cc engines. While four-cylinder engines are not typical in kei class cars, Subaru still primarily uses this layout. During the 20 years of kei car development, the two- and three-cylinder engines have improved to be on par with Subaru's four-cylinder designs.[1]

There was a turbocharged version, the EK23, used in the Subaru Rex, which competed with the Daihatsu Mira and Suzuki Alto. This was replaced with a supercharger. The EN-engine turbo version is not present in the following list, only the naturally aspirated and supercharged versions. The supercharged engine was nicknamed Clover, and Subaru engraved the head with a clover-leaf mark.

EN05[edit]

The EN05 was the first engine in the EN series. Variants include a naturally aspirated model with a carburetor, and the EMPi equipped with a supercharger. Cylinder dimensions are oversquare.

  • SOHC 8-valve
  • Displacement: 547 cc
  • Bore × stroke: 56.0 × 55.6 mm
  • Compression ratio: 10.0 (Naturally Aspirated carburetor) / 8.5 (supercharger)
  • Specifications: Naturally Aspirated carburetor 38PS / 7,500 rpm 4.5 kg m / 4,500 rpm (KH2 1986 Subaru Rex)
  • Specifications: supercharger 61PS / 6,400 rpm 7.6 kg m / 4,400 rpm (KH2 1986 Subaru Rex)

EN07A (Naturally Aspirated carburetor)[edit]

Installed in the Vivio Van.

  • SOHC 8-valve
  • Displacement: 658 cc
  • Bore × stroke: 56.0 × 66.8 mm
  • Compression ratio: 10.0
  • Specification Reference: 42PS / 7,000 rpm 5.3 kg m / 4,500 rpm (KW series Subaru Vivio)

EN07[edit]

The EN05 had its stroke lengthened to reach the new 660 cc limit set for kei cars by the Japanese government for March 1990.

EN07C (Naturally Aspirated carburetor)[edit]

The engine was installed in the early Sambar. Compression ratio dropped slightly, and tuning emphasized low-rpm torque.

  • SOHC 8-valve
  • Displacement: 658 cc
  • Bore × stroke: 56.0 × 66.8 mm
  • Compression ratio: 9.8
  • Specification Reference: 40PS / 6,500 rpm 5.5 kg m / 3,500 rpm (KV3 series Sambar)

EN07L (LPG carburetor version)[edit]

  • SOHC 8-valve
  • Displacement: 658 cc
  • Bore × stroke: 56.0 × 66.8 mm
  • Compression ratio: 9.8

Used in:

  • Subaru Sambar
  • Subaru Sambar Dias

EN07E (Naturally Aspirated EMPi)[edit]

The EN07A engine (with a carburetor) became EN07E with EMPi.

  • SOHC 8-valve
  • Displacement: 658 cc
  • Bore × stroke: 56.0 × 66.8 mm
  • Compression ratio: 10.0
  • Specification Reference: 38 kW (53PS; 52 hp) / 7200 rpm 53.9Nm (5.5 kg m) / 5600 rpm (KK3 VIVIO MT version)

Used in:

EN07F (Naturally Aspirated EMPi)[edit]

The EN07C engine (with a carburetor) became EN07F with EMPi. The rocker cover on the delivery service version had a crimson ceramic coating.

  • SOHC 8-valve
  • Displacement: 658 cc
  • Bore × stroke: 56.0 × 66.8 mm
  • Compression ratio: 9.8
  • Specification Reference: 35 kW (48PS) / 6,400 rpm 58 N m (5.9 kg m) / 3,200 rpm (TV1 series Sambar)

EN07S (Naturally Aspirated SPI)[edit]

Was installed in the Pleo Van EGI SPI (single point injection) engine design.

  • SOHC 8-valve
  • Displacement: 658 cc
  • Bore × stroke: 56.0 × 66.8 mm
  • Compression ratio: 10.0
  • Specification Reference: 45PS / 6,400 rpm 5.7 kg m / 4,000 rpm

Used in:

  • Subaru Pleo

EN07Y (supercharger EMPi)[edit]

The Rear engine/Rear drive version initially installed in the Sambar used a distributor, but a distributorless ignition was used from 1996 on. Like the EN07F, the high durability version used in the delivery-service version has a rocker cover decorated with a crimson ceramic coating.

  • SOHC 8-valve supercharger
  • Displacement: 658 cc
  • Bore × stroke: 56.0 × 66.8 mm
  • Compression ratio: 8.3
  • Specification Reference: 55ps / 6,200 rpm 7.1 kg m / 3,800 rpm (KV4 series Sambar Touring)
43 kW (58PS) / 6,000 rpm 74N m (7.5 kg m) / 4,400 rpm (TV1 series Sambar Dias)

EN07W (minor change SPI)[edit]

Equipped with a CVT for Pleo; previously called "mild change". For power and fuel economy the engine has both SPI and a low-pressure supercharger without intercooling.

  • SOHC 8-valve supercharger
  • Displacement: 658 cc
  • Bore × stroke: 56.0 × 66.8 mm
  • Compression ratio: 8.9
  • Specification Reference: 42 kW (58PS) / 6,400 rpm 74 N m (7.3 kg m) / 4,000 rpm

Subaru Pleo L (CVT transmission)

EN07U (mild change EMPi)[edit]

The EN07W engine became EN07U when fitted with EMPi and a small intercooler. The L-type Subaru Pleo late in the generation.

  • SOHC 8-valve supercharger intercooler (mild change)
  • Displacement: 658 cc
  • Bore × stroke: 56.0 × 66.8 mm
  • Compression ratio: 8.9
  • Specification Reference:: 44 kW (60PS) / 6,400 rpm 75 N m (7.6 kg m) / 4,000 rpm

Subaru Pleo L (CVT transmission)

EN07Z (IC supercharger with EMPi)[edit]

The EN variant for Rex's hot model and for Pleo RM. The MPI fuel injection (EMPi) was reset to make power at lower engine speeds.

  • SOHC 8-valve supercharger intercooler
  • Displacement: 658 cc
  • Bore × stroke: 56.0 × 66.8 mm
  • Compression ratio: 8.5
  • Specification Reference: 47 kW (64PS) at 6400 rpm, 84 N·m (8.6 kg·m) at 4400 rpm (Subaru Rex VX / Subaru Vivio GX)
64PS at 6000 rpm, 89 N·m (9.1 kg·m) at 3600 rpm (Subaru Pleo RM)

Used in:

EN07D (dohc AVCS)[edit]

The Subaru R2 was fitted with this version from its debut. It has a variable valve timing DOHC head and direct ignition.

  • DOHC 16-valve AVCS
  • Displacement: 658 cc
  • Bore × stroke: 56.0 × 66.8 mm
  • Specifications: 40 kW (54PS) at 6400 rpm. 63 N·m (6.4 kg·m) at 4400 rpm (R1, R2, Stella)

Used in:

EN07X (DOHC IC with supercharger)[edit]

VIVIO RX-R was developed at the time the DOHC head design appeared. It adopted direct push and a high lift cam like Toyota, but the timing belt drives only the exhaust camshaft; the method of driving the intake cam is synchronous from there. This 660 cc DOHC narrows the valve angle slightly aiming for a compact combustion chamber. The first-launched and latest versions take regular gasoline, but there is also a high-octane gasoline version. Cylinder head channel was changed for Subaru Pleo when heat damage appeared in the cylinder farthest away from the radiator.

  • Supercharger intercooler with a DOHC 16 Valve
  • Displacement: 658 cc
  • Bore × stroke: 56.0 × 66.8 mm
  • Compression ratio: 9.0
  • Specification Reference: 47 kW (64PS) at 7200 rpm 106 N·m (10.8 kg·m) at 4000 rpm (Subaru Vivio RX-R)
47 kW (64PS) at 6000 rpm 103 N·m (10.5 kg·m) at 3200 rpm (Subaru Pleo RS)

Used in:

EN08[edit]

The Subaru Fiori derivative of the Rex was also equipped with pink and blue pinstriping from factory and a 2 year, 50,000k warranty was offered when new. Equipped with a different engine, the Fiori had Subaru's 758 cc carburetted four-cylinder EN08 powerplant. Sold as the Fiori in Australia, this model was also marketed as the M80 and the Mini Jumbo in other export markets.

References[edit]

  1. ^ [1] (Japanese)
This article incorporates information from the equivalent article on the Japanese Wikipedia.

External links[edit]