stands for Four-Speed Electronic Automatic Transmission. This simply
means that your vehicle is equipped with an automatic transmission with
four gears. The gears for the 4EAT are as follows:
Automatic transmission gear ratios for 2.5RS:
1st - 3.027
2nd - 1.619
3rd - 1.000
4th - 0.694
Reverse - 2.272
Final drive ratio - 4.44
Each gear can be taken to
the following MPH
4EAT is also equipped with the VTD (Variable Torque Distribution) AWD
system. This AWD system adjusts power to wheels depending on driving
conditions, making it more technically advanced than the AWD system
used in manual-equipped vehicles. The normal driving split is 45% to
the front wheels and 55% to the rear wheels.
How does the 4EAT differ
from the 5MT? Is it better or worse for performance?
first difference between the 4EAT and 5MT is the AWD system. 5MT models
use a permanent 50/50 split between the front and rear wheels, whereas
models equipped with the automatic make use of the technically superior
VTD system (mentioned above). The second difference is the gearing. The
4EAT uses 4 gears to make use of its power, where 5MT models make use
of 5 gears.
a stop: The 4EAT (stock) is much different performance-wise than the
5MT. Models equipped with the 5MT are able to achieve their
pavement-rippling sub-six second 0-60 and low 14 second ¼ mile times
thanks to its ability to launch at 4000+ RPM. Models equipped with the
4EAT must use the brake-torque technique (I also take no responsibility
for potential damage caused to your car using this technique), however,
stock 4EATs using this method can only launch at a maximum 3200 RPM,
leading to a 0-60 time in the low 7 second range and a ¼ mile in the
mid-to-high 15 second range.
a roll: Judging from the very few 4EAT vs 5MT races that I have
studied, a 5MT will have about a 2 car lead on a similarly equipped
4EAT in a race from 40 MPH to 100 MPH. Please note that in the few
documented races known, the 4EAT begins to trail after it shifts to 3rd
gear, leading me to believe that the 4EAT’s major weakness are it’s
5MT models dyno at around 170 WHP where 4EAT models dyno at around 150
WHP. From my research, I have noticed about a 20-25 WHP difference
between similarly equipped 4EAT and 5MT WRX’s due to the extra
driveline loss through the torque converter.
What you need to make the
4EAT comparable to a 5MT in acceleration and ¼ mile times.
need a high stall torque converter. The main purpose of this mod is to
raise the stall speed from 3200 RPM to around the 4200 RPM range;
allowing the 4EAT to run 0-60 and quarter mile times consistent with
5MT equipped vehicles. This mod is a MUST HAVE if you
are planning on consistently drag racing your vehicle. The use of this
mod for owners whom do not consistently drag race is debatable. Some
argue that it increases daily drivability; others argue that it does
not. You’ll have to decide.
I am not interested in 0-60
or ¼ mile times, how else can I make my 4EAT a better daily driver?
this is highly subjective, the general consensus is that the best
method to increase your 4EAT’s drivability is by installing an
aftermarket header, uppipe and turbo back exhaust system . This will
virtually eliminate turbo-lag and give much better low and mid-range
power. You can also add engine management to take full advantage of
your modifications to further increase responsiveness and decrease lag.
Best First Mod for the 4EAT
the idea of the best first mod is highly subjective, I, along with many
others, feel that an aftermarket exhaust system is the best first
modification for the money. This modification greatly decreases
turbo-lag, causing the car to perform better in all circumstances.
Best New Turbo for the 4EAT
have found that a GT30R is the best turbo replacement for the 4EAT.
Both the VF 34 and 39 have decent spool-up, with good mid-range and top
end. If you plan on doing short block upgrades and running higher than
18 psi, then we have found the GT30R to the our favorite.
course, you will also need the necessary supporting mods to run a new
turbo. A great deal of research must be done if you decide that a new
turbo upgrade is right for you.
Using a Blow-Off Valve on a
it can be done, but the difference between using a BOV on a 4EAT is
that you will not hear much of the “pssshhh” sound when the
transmission shifts. This is because the 4EAT holds its boost during
I heard that the
transmission in the Auto can hold more power than the transmission that
is used in the manual. Is this true?
this is true up to a point. The general consensus is that the 4EAT is a
stronger transmission than the 5MT and will last a very long time as
long as it is properly maintained and the abuse is kept to the minimum.
The 4EAT is an extremely hard transmission to “break,” but it is unable
to cope with too much extra power because its shifts are still tuned
for stock levels. Once you begin to cross to cross the 250 WHP barrier,
you need to consider “beefing up” your transmission with a performance
torque converter and valve body upgrade. This need increases if you
plan on launching your vehicle or driving it hard on a consistent
basis. Very few people have actually broken the "teeth" of the 4EAT,
and with a full internal transmission upgrade, the 4EAT will handle
Can I manually shift the transmission ala Manumatic?
available as a true manumatic in Japan, the American version of the
automatic WRX does not contain that feature. You may manually select
the gears, although there is little purpose as A) manually shifting
from a stop will not net you better acceleration and B) it does put
extra stress on your transmission. I manually shift the automatic from
a stop frequently and through the gears without any issues.
the manual functionality of the 4EAT can be useful for proper power
delivery when cornering, it can also be used to place the car in a
better gear when racing from a roll.
automatic in the WRX is a lot different than any other automatic that I
have driven. The 5MT guys can choose the gear that they want their car
to be in, keeping the car in it’s optimal power band. We can do that as
well, it just takes knowing how to fully use the automatic to take
advantage of the car’s power band. Lets review the different gear
selections on the automatic gear shifter. (please note that the
following information is intended towards stock vehicles. The rules are
completely different for modded or even lightly modded cars).
This is a special situation gear (explained further in the manual) It
should be used rarely, if never. Some owners like to start out in 1 to
‘manually shift” the gears. Please note that the transmission will not
automatically upshift while in 1, so when you shift into the next gear,
make sure to do so at least 1000 RPMs early because of the shifting
This is also a special situation gear (explained further in your
manual). Starting off in 2 will start your car in 2nd gear, not first,
making it perfect for dyno tuning, but doesn’t make much sense for
daily driving. Please note that the transmission will not automatically
upshift, so make sure to shift at least 1000 RPM early because of the
gear is sometimes referred to in other cars as “D.” By selecting 3, the
car will drive normally but will not upshift into 4. Selecting 3 is
ideal when you are driving in any situation where you will not be
maintaining a constant speed (while driving in the city, for example,
or climbing a steep grade). By selecting 3, your car will also be much
more willing to downshift into 2 when extra power is required, making 3
the Power Gear of the WRX. Interestingly enough, there have been some
reports of a .2 second better time at the track thanks to the more
aggressive torque split while in 3.
is sometimes referred to in other cars as “OD.” By selecting D, the car
will drive normally and shift into 4th gear as soon as it can. This is
only ideal while maintaining a constant speed (Highway, freeway
driving). While in D, the car does not like to downshift into 2nd gear,
making it a poor gear selection for times when quick passing response
Why the 4EAT is better
then the 5MT.
of us are forgetting the main advantage of the Auto-WRX: the AWD system
itself. When we talk of "Rally Proven", the "proof" is actually missing
in the Manual-WRX. Here is the reason why:
VTD-AWD system of the Auto-WRX is the most advanced AWD system of
Subaru, with a true torsen (torque sensing) planetary gear center
differential, which works in association with electronically controlled
continuously variable multi-plate clutch-packs. The torque split is at
45/55, with a slight rear bias in power, in normal driving, unless more
is needed front or back. This system equals in sophistication and
effectiveness, the best AWD systems currently available in the market
including the Audi Quattro (not the "Quattro" present in the Audi TT,
which is inferior to the VTD-AWD). The VTD-AWD system is conceptually
identical to the AWD systems present in the World Rally Conquering
Subarus, the significant difference being that the WRC cars have driver
adjustable torque splits and are much more of a heavy-duty kind. The
hardware otherwise is identical in design. The Rally Subarus also have
a true auto-manual transmission, which is actually a clutch-less
manual, but the underlying AWD system is better adaptable to the
Auto-WRX, not the manual-WRX, due to which the manual-WRX soldiers on
with an AWD system that is essentially tractor-technology. "Gets the
job done" but nothing to write home about.
The other Auto-Subarus do not have the
torque-sensing center differential and drive more like a FWD car in
manual WRX on the other hand, has the same Viscous coupling AWD system
present in all other manual Subarus, which is a reactive system, as
opposed to the proactive nature of the VTD-AWD system of the Auto-WRX.
The viscous fluid which is used to transfer torque front/back needs
slippage before it can react and transfer torque. Also, since
differential lock is achieved due to the viscous fluid being twisted
(unlike the torque sensing incredibly sturdy planetary gear
differential in the Auto-WRX), the torque-transfer is both slow and in
efficient. The AWD system of the manual WRX cannot be compared with the
Audi Quattro or any other sophisticated AWD system. It does not have
the breadth of operation (cannot transfer the amount of torque
front/back like the VTD-AWD), the reactiveness (reacts slowly due to
its very Viscous coupling nature) or the rapid torque transfer
characteristics (due to the "reactive" nature of the system) of the
VTD-AWD equipped Auto-WRX. With the Viscous coupling AWD system present
in the manual-WRX, Subaru certainly would not be winning many
rallies....just a heads-up.
else remaining the same, I would have preferred a manual in the WRX.
But in this particular case, everything else is not the same. Far from
it! Let’s face it - we love these cars for their AWD systems and not
for their "manual gear shift capability".
So on that criteria,
Manual-WRX has a huge and glaring deficit and the 4EAT is the “Best