One of the biggest recent movers in the high performance scene has been
Subaru (aka Fuji Heavy Industries). Since the release of the Liberty (Legacy) RS side-by-side
with the SVX, Subaru has continued to build grunty engines with a reputation for
reliability.
Modern Subaru engines are identified by a fairly simple four-character code
system. The first two characters are letters that indicate the engine family and
the second two characters are numbers relating to engine capacity.
Here’s some common Subaru engine codes and what they identify...
|
Engine Code |
Engine Configuration/ Capacity |
|
EJ18 |
Flat-four/1.8 litre |
|
EJ20 |
Flat-four/2.0 litre (available in naturally aspirated and turbocharged
form) |
|
EG33 |
Flat-six/3.3 litre |
|
ER27 |
Flat six/2.7 litre |
|
EN07 |
In-line four/660cc (available in naturally aspirated and turbocharged
form) |
Subaru Sixes...
The most potent six-cylinder release from Subaru is the EZ30-R 3.0-litre
DOHC, 24-valve flat-six as fitted to the current top-line Japanese Legacy
Touring Wagon, B4 and Outback (the latter also available in Australia). This
all-alloy motor features AVCS+ continuously variable inlet valve timing (across
a 50-degree range) along with variable valve lift. As far as we can
determine, variable valve lift in this engine is a first for Subaru. Using a 10.7:1 compression
ratio, this sporting engine is rated with a healthy 184kW at 6600 rpm and 304Nm
at 4200 rpm. In Australian delivered guise (in the new Outback 3.0R) it delivers
4kW and 7Nm less. A very desirable engine.
Almost as powerful – thanks to a capacity advantage – is the early ‘90s EG33
3.3-litre DOHC, 24-valve flat-six, as fitted to the Subaru SVX coupe. The engine
uses a variable induction system, twin knock sensors, 10.0:1 compression and -
in Japanese guise - it generates an impressive 179kW at 6000 rpm together with
309Nm at 4800 rpm. Australian delivered examples make 172kW. Like most Subaru
engines, the EG33 has many engineering ties to the EJ-series flat-four of the
same era.
Next most powerful is the EZ30 3.0-litre, DOHC, 24-valve flat-six as fitted
to the mid-range version of the Japanese Legacy. Using the same 10.7:1
compression ratio as the hot EZ30-R engine and with a variable induction system,
this motor puts out 162kW at 6000 rpm and 289Nm at 4400 rpm.
Australian-delivered EZ30s (non AVCS+) make 154kW and 282Nm at the same revs as
the Japanese version.
Reaching back into history, the Japanese model mid ‘80s Subaru Vortex was
released with an optional 2.7-litre flat-six. The SOHC fuel injected ER27 was no
powerhouse at 112kW, but it was Subaru’s first attempt at a mass produced
six-cylinder. Things have improved!
Subaru Fours...
Subaru has earned an enviable go-fast image in the past 10 – 15 years.
The real action started in Japan during
1989, when the local market received the Legacy RS. The RS debuted the
now-famous EJ20 2.0-litre turbo engine with DOHC, 16-valve breathing, single
turbocharger and an intercooler (which was water-to-air in those early days).
Using 8.0:1 compression, the first Japanese-spec Legacy RSs could crank out
147kW at 6000 rpm and 260Nm at 3600 rpm. The same output was claimed by the
Australian-delivered Liberty RS of the early ‘90s (essentially a facelift of the
original Liberty/Legacy design).
The EJ20 turbo engine has since evolved with various different compression
ratios, camshafts, turbocharger sizes, intercoolers and more. There is a
bewildering number of variations, but the more common later-model EJ20 turbo
engines are rated at 162, 176, 184 and 206kW. These outputs became available in
GC-series Impreza WRX sedans and wagons.
Today, the latest Japanese-spec WRX EJ20 turbo engine uses 9.0:1 compression,
AVCS variable inlet cam timing and makes 184kW with 333Nm. The current Legacy GT
also uses a single (twin scroll) turbo with AVCS and makes up to 206kW and 343Nm
at a low 2400 rpm.
In
Australia, the
’94 – ‘96 EJ20 turbo engine used a large TD05 turbocharger to make 155kW at 6000
rpm and 270Nm at 4800 rpm. The ‘97/’98 model got a smaller, more responsive
turbocharger and a larger intercooler (amongst other things) but output remained
at 155kW – though peak power was now at a more accessible 5600 rpm and there was
an extra 20Nm 800 rpm lower than before. For the ‘99/’00 power increased to
160kW – with no explanation of how... Power remained at 160kW until the release of
the ’03/’04 Australian-spec WRX.
The current model Australian
WRX uses a 9.0:1 static compression ratio, AVCS variable valve timing and makes
168kW and 300Nm (at 6000 and 3600 rpm). The local Liberty GT also carries over
the EJ20 single turbo design but generates a tidy 180kW at 6400 rpm and 310Nm at
just 2400 rpm. At 9.5:1, its static compression ratio is high for a turbocharged
engine.
A twin-turbocharged version of the EJ20 - as previously fitted to the
Liberty/Legacy B4 – was also introduced in
Japan in about
1994. Using a sequentially staged pair of turbochargers and an air-to-air
intercooler, these engines started off generating 194kW but soon rose to the regulation 206kW output. Note
that output depends on whether the vehicle is fitted with a manual or auto
transmission – and whether it is detuned for the Australian market. One thing to
plague all EJ20 twin-turbo engines is a mid-range torque hole that occurs as the
secondary turbocharger comes into action. Subaru has now dropped the sequential
twin-turbo engine...
But the most desirable EJ20 turbo engines are those tweaked by STi. Bigger
turbochargers, improved intercoolers with water sprayers, stronger engine
internals and a more aggressive overall tune are hallmarks of a STi rework...
Today, the latest Japanese-spec Impreza STi uses 8.0:1 compression, a
twin-scroll turbocharger and AVCS variable inlet cam timing to reach 394Nm at
4400 rpm and the regulation 206kW output. Note that the same 206kW output has
been achieved by most Impreza STis since late ’96. In comparison, the current
Australian-spec STi (with the same mechanicals) is rated at a more modest 195kW
and 343Nm.But there’s nothing modest about the Impreza STi that’s currently on
offer in North America! The North American STi uses a
2.5-litre capacity (a 25 percent advantage) and thrusts out a substantial 224kW
and 408Nm...
Outside of the American Impreza
STi, the turbocharged 2.5-litre flat-four – the EJ25-T – can be found in the
current Australian Forester XT. Tuned for maximum driveability, this DOHC turbo
engine generates 155kW at 5600 rpm and 320Nm at 3600 rpm. In
Japan,
meanwhile, a Forester STi is available pushing out a massive 195kW – as seen in
this graph.
The hottest atmo version of the
2.5-litre flat-four is the Japanese-spec EJ25 DOHC, 16-valver with AVCS that
makes 125kW and 238Nm at 6000 and 2800 rpm respectively. Unfortunately,
Australia has
never received this engine – we get the SOHC version, which currently makes
121kW and 226Nm. Earlier Australian-spec 2.5s made just 119kW and 211Nm.
You might also be interested in
another motor not seen in
Australia - the
highly tuned atmo version of the EJ20. Factory fitted to the current
Legacy 2.0R 5-speed manual, this engine employs a high 11.5:1 compression ratio
and DOHC, 16-valve heads with AVCS. Output is an impressive 140kW at 7100 rpm
(!) with 196Nm at 4400 rpm.
On the smaller side of things,
the Subaru EN07 engine flies the flag. Displacing just 660cc, the EN07 is
available in various different guises but the hottest is fitted to the Japanese
Pleo and R2-S Kei-classer. With DOHC, 16-valve breathing, a 9.0:1 static
compression ratio and the aid of a supercharger and intercooler, this in-line
four-banger slogs out 47kW at 6000 rpm. Peak torque is 103Nm at 3200 rpm. A
naturally aspirated DOHC version with AVCS is also available – this makes 40kW
at 6400 rpm.
For those with a good memory, Subaru also dabbled with turbocharging in the
early/mid ‘80s with their EA-series flat-four. The ‘ultimate’ OHC version of the
EA82 1.8-litre turbo came non-intercooled and producing up to a meagre 101kW at
5600 rpm. While it's no powerhouse, these engines are tough-as-nails – something
Subaru has built its reputation on.
Subaru Performance Motors at a Glance...
Sixes |
|
EZ30-R 3.0 litre flat-six DOHC (AVCS+) |
184/180kW |
|
EG33 3.3 litre flat-six DOHC |
179/172kW |
|
EZ30 3.0 litre flat-six DOHC |
162/154kW |
|
ER27 2.7 litre flat-six SOHC |
112kW |
Fours |
|
EJ25 2.5 litre DOHC Turbo (US STi) |
224kW |
|
EJ20 2.0 litre DOHC Turbo |
147 - 206kW |
|
EJ20 2.0 litre DOHC Twin Turbo |
194 - 206kW |
|
EJ25 2.5 litre DOHC Turbo (Forester STi) |
195kW |
|
EJ25 2.5 litre DOHC Turbo |
155kW |
|
EJ20 2.0 litre DOHC (11.5:1 CR) |
140kW |
|
EJ25 2.5 litre DOHC |
125kW |
|
EJ25 2.5 litre SOHC |
121/119kW |
|
EA82 1.8 litre SOHC Turbo |
101kW |
|
EN07 660cc DOHC Supercharged |
47kW |
|
EN07 660cc DOHC AVCS |
40kW |
|