The SVX debuted with and remained available with only one engine, the EG33 model 3.3-liter boxer horizontally opposed flat-six.
This engine was the largest engine produced by Subaru for its passenger cars until the introduction of the 3.6-liter EZ36 engine in the 2008 Subaru Tribeca.
The previous generation Subaru Alcyone had a turbocharged four-cylinder engine, but the larger EG33 was more powerful and so a turbo was not installed.

Internally, the engine is essentially a six-cylinder variant of the EJ22 found in the first-generation Japanese market Legacy and Impreza.
The new 3.3-liter variant was equipped with DOHC and four valves per cylinder, and had an increased compression ratio of 10.1:1, bringing horsepower up to 172 kilowatts (231 hp) at 5,400 rpm with 309 newton metres (228 lb⋅ft) of torque at 4,400 rpm.
Fuel delivery was accomplished with sequential multi-port fuel injection with dual-spray injectors.
Engine ignition used platinum spark plugs and a computerized management system with "limp home feature", which included over-rev protection, as well as monitors for fuel injection and ignition.

The exhaust system consisted of head pipes from each bank of cylinders with their own pre-catalytic converters, which entered a dual-inlet / single outlet main catalytic converter.
A single 2.5-inch (64 mm) exhaust pipe exited the main converter and went into a resonator, and onto the main, transverse, single-inlet muffler with twin exhaust tips in the bumper.

The SVX was offered solely with an automatic transmissions, as Subaru did not offer a manual transmission capable of handling the horsepower and torque of the EG33 engine at the time.

Subaru offered two all-wheel drive systems for the automatic transmission, called ACT-4 or VTD.
The first system, called ACT-4 (active torque split) was introduced on the 1988.5 Alcyone using an electronic control unit to vary the torque applied to the rear wheels dynamically based on driving conditions.
As an active system, it varied the torque split infinitely based on several inputs.
This AWD system was used throughout the entire production run in vehicles manufactured for sale in the US, Canada, Germany, France and Switzerland.
A more advanced system called VTD (variable torque distribution), was introduced and used on SVX for sale in Japan, the UK, the Benelux region, Sweden, Australia, Spain, Austria and Brazil.
The VTD AWD system adds a planetary center differential.
The system retains the use of the ACT clutch and active control, though its size and role are much smaller as it is used only to suppress differential action instead of the complete differential function.
When no speed difference exists between front and rear, the entire VTD gear rotates as a unit and torque split is at a mechanical 36/64 biased by the planetary gear ratio.
The clutch is incorporated to prevent and suppress any differential action that may occur as the planetary gear will send virtually all torque to the axle with the highest speed if not restrained.
By using a similar logic to the previous ACT system, the clutch can theoretically direct any percentage of torque to either axle, but in practice the variation remains between 34-50% front and 64-50% rear.
This system is not capable of operating in 2WD and therefore could not be used on 2WD dynos as required for emissions testing in some states.
This prevented VTD as an option on Subaru vehicles offered for sale in US until passenger car regulations were changed, which occurred long after the end of svx production.
It was later introduced to the US with the Outback VDC.

Problems with early SVX transmissions included a defective torque converter clutch which disintegrates and clogs early radiators (both clutch and radiator changed in 1993), and had systemic high clutch failures due to lower than spec pump pressure, fluid evacuation, and clutch balance pressure.
Several major revisions were made, all of which are included by late 1994 production.
Shortly after the SVX ended production Subaru transitioned to a completely redesigned 4 speed unit.

The Japanes
The SVX debuted with and remained available with only one engine, the EG33 model 3.3-liter boxer horizontally opposed flat-six. This engine was the largest engine produced by Subaru for its passenger cars until the introduction of the 3.6-liter EZ36 engine in the 2008 Subaru Tribeca. The previous generation Subaru Alcyone had a turbocharged four-cylinder engine, but the larger EG33 was more powerful and so a turbo was not installed.
Internally, the engine is essentially a six-cylinder variant of the EJ22 found in the first-generation Japanese market Legacy and Impreza. The new 3.3-liter variant was equipped with DOHC and four valves per cylinder, and had an increased compression ratio of 10.1:1, bringing horsepower up to 172 kilowatts (231 hp) at 5,400 rpm with 309 newton metres (228 lb⋅ft) of torque at 4,400 rpm. Fuel delivery was accomplished with sequential multi-port fuel injection with dual-spray injectors. Engine ignition used platinum spark plugs and a computerized management system with "limp home feature", which included over-rev protection, as well as monitors for fuel injection and ignition.
The exhaust system consisted of head pipes from each bank of cylinders with their own pre-catalytic converters, which entered a dual-inlet / single outlet main catalytic converter. A single 2.5-inch (64 mm) exhaust pipe exited the main converter and went into a resonator, and onto the main, transverse, single-inlet muffler with twin exhaust tips in the bumper.
The SVX was offered solely with an automatic transmissions, as Subaru did not offer a manual transmission capable of handling the horsepower and torque of the EG33 engine at the time.
Subaru offered two all-wheel drive systems for the automatic transmission, called ACT-4 or VTD. The first system, called ACT-4 (active torque split) was introduced on the 1988.5 Alcyone using an electronic control unit to vary the torque applied to the rear wheels dynamically based on driving conditions. As an active system, it varied the torque split infinitely based on several inputs. This AWD system was used throughout the entire production run in vehicles manufactured for sale in the US, Canada, Germany, France and Switzerland. A more advanced system called VTD (variable torque distribution), was introduced and used on SVX for sale in Japan, the UK, the Benelux region, Sweden, Australia, Spain, Austria and Brazil. The VTD AWD system adds a planetary center differential. The system retains the use of the ACT clutch and active control, though its size and role are much smaller as it is used only to suppress differential action instead of the complete differential function. When no speed difference exists between front and rear, the entire VTD gear rotates as a unit and torque split is at a mechanical 36/64 biased by the planetary gear ratio. The clutch is incorporated to prevent and suppress any differential action that may occur as the planetary gear will send virtually all torque to the axle with the highest speed if not restrained. By using a similar logic to the previous ACT system, the clutch can theoretically direct any percentage of torque to either axle, but in practice the variation remains between 34-50% front and 64-50% rear. This system is not capable of operating in 2WD and therefore could not be used on 2WD dynos as required for emissions testing in some states. This prevented VTD as an option on Subaru vehicles offered for sale in US until passenger car regulations were changed, which occurred long after the end of svx production. It was later introduced to the US with the Outback VDC.
Problems with early SVX transmissions included a defective torque converter clutch which disintegrates and clogs early radiators (both clutch and radiator changed in 1993), and had systemic high clutch failures due to lower than spec pump pressure, fluid evacuation, and clutch balance pressure. Several major revisions were made, all of which are included by late 1994 production. Shortly after the SVX ended production Subaru transitioned to a completely redesigned 4 speed unit.
The Japanes
Subaru Alcyone SVX