Subaru has become popular in performance circles
largely thanks to its rally-proven EJ20 2-litre turbo engine. But the Japanese
company is also more than capable of building some damn fine six-cylinders –
with up to 184kW available from a beautifully free-spinning 3-litre six, there’s
a whole world of Subaru performance engines that go barely noticed.
So let’s sit up and take notice!
Early Subaru 6s
The first six-cylinder engine manufactured by
Subaru appeared in the 1989 model year – at around the same time the EJ20
four-cylinder turbo was born.
As the boxy looking Alcyone (aka Vortex) coupe
neared the end of its life, Subaru quietly introduced a six-cylinder version as
an option to the existing four-cylinder models. The six-cylinder Alcyone was
intended as the sophisticated, top-of-the-line version and was sold with a
standard four-speed auto and constant AWD.
Interestingly, the new six – coded ER27 – is
essentially a Subaru EA82 four-cylinder with a couple of extra pots. It’s a
horizontally-opposed design and the block and heads are made from
aluminium. Bore and stroke dimensions are 92 and 67mm respectively (identical to
the EA82) and total swept capacity is 2672cc. With relatively plain SOHC heads,
a 9.5:1 compression ratio, multi-point fuel injection and a distributor ignition
system, the ER27 is rated at 112kW at 5200 rpm and 211Nm at 4000 rpm. This is
achieved on normal unleaded fuel. The ER27 engine was seen in the Japanese
domestic market and America only.
The six-pot Alcyone went relatively unnoticed
until the formula was reinvented for the 1991 release of the Alcyone SVX (known
as simply SVX in most counties). The SVX brought much more stylish lines and, as
a result, the car received more attention. Under the bonnet lives a new
all-alloy EG-series six-cylinder engine – the horizontally-opposed EG33. At 3.3
litres (with a massively over-square 96.9mm bore and 75mm stroke), the SVX
engine holds a significant capacity advantage and benefits from DOHC,
four-valve-per-cylinder heads. A dual-stage induction system is also
incorporated to improve the spread of torque.
In Japanese spec, the EG33 puts out an impressive
179kW at 6000 rpm and 309Nm at 4000 rpm. Its 10:1 compression ratio requires
premium unleaded but there are twin knock sensors to alter the timing of the
direct-fire ignition system. Australian delivered versions are detuned slightly
to 172kW at 5600 rpm and 304Nm at 4000 rpm. Sales of the SVX dribbled through
until 1997.
Like its predecessor, the EG33 is engineered for
longitudinal mounting and comes tied to a standard four-speed AWD transmission.
This is a top-notch engine that, even by today’s standards, puts out excellent
power and torque. It also remains the largest engine produced by Subaru. Note
that the EG33 also has many similarities with the EJ-family four-cylinder – the
EG33 shares the same bore and stroke dimensions as the EJ22.
Late Subaru 6s
Subaru took a break from six-cylinders during the
late ‘90s but released a newie in 2000.
Introduced in the Japanese-spec Subaru Legacy
Lancaster 6 wagon, the new-generation six-cylinder is coded EZ30. The EZ30 has a
more balanced bore/stroke ratio (at 89.2 and 80mm respectively) and swept
capacity is 2999cc. Interestingly, minimising the distance between cylinders and
switching from a belt to a chain cam drive helped Subaru reduce the length of
the six-pot engine – it’s just 20mm longer than the EJ-series four cylinder!
Again, the EZ30 uses DOHC, multi-valve breathing and a variable induction
system. With a compression ratio elevated to 10.7:1 (requiring the use of
premium unleaded fuel), the EZ30 outputs 162kW at 6000 rpm and 289Nm at 4400
rpm. A four-speed auto comes standard – with trademark Subaru AWD, of course.
The same EZ30 engine was released in the
Australian-spec 2000 Subaru Outback H6 but output is choked down to 154kW at
6000 rpm and 282Nm at 4400 rpm. We believe this output is achieved on normal
unleaded fuel.
In 2002, the Japanese market EZ30 was given the
tweak it really needed to be taken seriously as a high-performance engine.
Subaru treated their 3-litre motor to AVCS+ continuously variable inlet valve
timing (across a 50- degree range) along with variable valve lift. VTEC style!
Cam switching occurs between 2000 and 4000 rpm depending on load. Retaining the
base engine’s 10.7:1 compression ratio, the newly created EZ30-R engine screams
out 184kW at 6600 rpm and 304Nm at 4200 rpm. This engine is reserved for
top-line versions of the 2002-onward Legacy wagon, Outback and B4.
The EZ30-R can also be found from late ’03 in the
local Outback 3.0R where it delivers slightly less grunt on 95 RON fuel – 180kW
and 297Nm. A five-speed auto trans is also adopted in place of the previous
four-speeder. In 2004, the Liberty 3.0R sedan and wagon was introduced sharing
the same driveline. A six-speed manual was also offered in the Liberty range.
Obviously, the EZ30-R engine is the hot choice in
the Subaru six-cylinder line-up but, given its age, we’d expect these engines to
be very expensive at the import wreckers - not to mention rare (we are yet to
see one). If you want maximum bang for buck, you can’t go past the big-cube EG33
from the SVX – with 179kW in Japanese guise, these engines are perfect for
conversions into Subaru Liberties/Legacies. Oh, and they’re also dirt cheap
because it seems nobody wants ‘em – we’ve seen a complete SVX half-cut at an
import wrecker for around AUD$2000!
Now, the next logical step is to create an EG33
turbo...
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