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 4-cylinder engine block and the cylinder were based on the EK23. Subaru did make a three-cylinder engine, called the Subaru EF engine that was used in the Subaru Justy, but the 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 4-cylinder engines are not typical in kei class cars, Subaru still primarily uses 4-cylinder engines. 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.
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 was first in the EN series. Variants include the Naturally Aspirated with a carburetor, and the EMPi equipped with a supercharger. Cylinder dimensions are over-square.
Installed in the Vivio Van.
The engine was installed in the early Sambar. Compression ratio dropped slightly, and tuning emphasized low-rpm torque.
Used in Subaru Sambar Subaru Sambar Dias
The EN07A engine (with a carburetor) became EN07E with EMPi.
Used in Subaru Rex Subaru Vivio Subaru Pleo
The EN07C engine (with a carburetor) became EN07F with EMPi. The rocker cover on the delivery service version had a crimson ceramic coating.
Was installed in the Pleo Van EGI SPI (single point injection) engine design.
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.
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.
Subaru Pleo L (CVT transmission)
The EN07W engine became EN07U when fitted with EMPi and a small intercooler. The L-type Subaru Pleo late in the generation.
Subaru Pleo L (CVT transmission)
The EN variant for Rex's hot model and for Pleo RM. The MPI fuel injection (EMPi) was reset to make power at lower rpm.
Used in Subaru Rex VX Subaru Vivio GX Subaru Pleo RM
R2 was fitted with this version from its debut. It has a variable valve timing DOHC head and direct ignition.
Used in Subaru R2 Subaru R1 Subaru Stella
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.
Used in Subaru Vivio RX-R Subaru Pleo RS Subaru R2 Subaru R1 Subaru Stella
The Subaru Fiori derivative 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 4-cylinder EN08 powerplant.