Toyota Century V12 Engine
Article by: BRADSHAW PHILIP
The GZG-50 Toyota Century
Phone (New Zealand):
Some people will be aware of my mythical 34
‘Ford’ Woodie Station Wagon hotrod project that never makes any
headway due to a tendency for other projects to materialise and
take priority. Consequently ‘progress’ on the Woodie in real
terms equates to the slow accumulation of bits.
Almost as mythical as my
Woodie Project is the existence of a Toyota V12. I first heard
rumours of this engine about 6 years ago and physically clapped
eyes on one in a Century Limousine on display at a Tokyo Toyota
dealer during a visit to Japan some four years ago. At the time
This is the virtually
hand built limousine that features the 5 litre quad cam V12 that
I oh so want. No idea what I would do with it; I just want one.
In fact, more than ‘want’, I think I actually ‘need’ one!
Well, I have managed to
go one step better than ‘need’ and bought one for the Woodie
late last year.
A quick history lesson might be in order. Contrary to popular
belief the Lexus isn’t Toyotas Flagship model – that
responsibility falls to the Century Limousine. The Century was
launched way back in 1967 as an executive limousine for high
ranking Japanese governmental and business officials, with
modified versions used for the Japanese imperial Household. The
name is derived from its launch marking the 100th
anniversary of the birth of
Toyota founder Sakichi
The Century originally grew out of the V8 Toyota Crown with the
first generation body remaining externally virtually unchanged
until 1997 (apart from driveline and interior upgrades). An
entirely new model was released in 1997, however, the car’s
external appearance remained understated and was clearly a
descendant of the original.
Photo Courtesy of:
Under the skin was a
completely different story with the 1997 GZG-50 series Century
debuting Toyota (and Japan’s) first and only production V12
engine, the 1GZ-FE. The Century currently retails for the
equivalent of $US 95,000 in Japan, which has to be a bargain
considering the exterior sheet metal is literally polished
Given that the Century
is predominantly sold only in Japan with a monthly sales target
of 200 units it seems incredible that Toyota took the plunge to
develop the V12 and I wouldn’t be surprised if the car is
actually sold at a loss. After all, the profit from the
production of a few thousand Corollas per day have to go
Odds are that, like me,
your principal interest in the Century is as a source of an
engine – so might be best we ignore the rest of the car, which
is in fairness pretty trick. I’m just not really inclined to fit
electric curtains to the Woodie…
So, what exactly is a 1GZ-FE?
In simple terms it is a 5 litre, all alloy, 48 valve quad cam
V12. Of course, like many things Toyota ‘simple’ is a word that
really doesn’t apply. Short of adding boost of some kind
(probably best to leave that sort of thing up to others, who
have indeed done so – can you say 1000 horsepower…?) Toyota
basically ticked every single box on the feature menu:
- 6 bolt mains
- forged steel crank
- alloy block and
variable inlet valve timing (VVTI)
- variable length
inlet runners (ACIS)
- direct fire
ignition with waste spark
- electronic throttle
control (‘fly by wire’)
As such the 1GZ-FE is one of Toyota’s family of ‘BEAMS’ (Breakthrough
Engine with Advanced Mechanism System) engines such as the 3S-GE
fitted to the Altezza. The 1GZ-FE in
many ways is two inline six cylinder engines sharing a common
crank. This is evidenced by there being dedicated left and right
cylinder bank inlet manifolds, throttle bodies and EFI systems –
to the extent that there are separate ECUs for each bank, with
the engine capable of running as a six cylinder engine (with a 6
cylinder air compressor along for the ride) should one bank
suffer a significant failure.
Here are some basic specs for you:
Total displacement (cc)
Number of cylinders
60 degree V12
Bore x stroke (mm)
81.0 x 80.8 (same
as the 2.5
litre 1JZ 6 cylinder)
Pent roof type
10.5:1 (97 octane or better recommended)
Fuel supply system
Electronic Fuel Injection (EFI)
Fuel Tank Capacity
DOHC 4-valve; chain and gear drive
Maximum output (PS @ rpm)
280 @ 5,200 net
Maximum torque (kg-m @ rpm)
49.0 @ 4,000 net
Spark plug type and gap
Iridium SK16R11 1.0-1.1 mm gap
Intake valve opening
-7 to 53 degrees BTDC
Intake valve closing
57 to -3 degrees ATDC
Exhaust valve opening
41 degrees BBDC
Exhaust valve closing
3 degrees ATDC
API SH EC-II, SJ EC or ILSAC
Oil viscosity and capacity
5W-30. Capacity 8 litres
In typical Japanese
style the engine officially makes ~280 horsepower, with export
versions rated at a mild 220 kW (pretty much 300 horsepower) and
a relatively sedate 460 Nm of torque (about 350 ft.lbf). The
scary bit is it makes over 400 Nm of torque from 1000 rpm which
endows the 2000kg Century with quite surprising performance.
Compare that to the 1UZFE V8 figures in the graph below to gain
an appreciation of just how much additional torque the V12
In real terms the V12
makes almost as much power and ultimately more torque across the
entire rev range than the famous 1980s Ferrari BB 512…. Should
come in handy for getting the Woodie up hills.
As befits a flagship model Toyota set out to produce an engine
with unparalleled smoothness. A V12 not only has inherent
prestige, it also has inherent smoothness due to the shorter
interval between successive power strokes - literally occurring
three times as frequently as those in a four cylinder for any
chambers, iridium electrode spark plugs and Variable Valve
Timing-intelligent (VVT-i) combine to stabilise combustion and
enable smooth engine operation Toyota describes as ‘like that
found in electric motors’. VVTI operates on the inlet cams only
and advances valve timing by up to 60 degrees.
The valve angle in the
heads is 24.3 degrees. Inlet valves are 30 mm diameter and
exhaust 24.5. Both share 5.5 mm diameter stems. The valve
adjusting shim has a titanium coating and sits above the
aluminium alloy valve lifter buckets.
the valve timing to best suit driving conditions increases
torque, output and fuel efficiency whilst reducing NOx and HC
emissions. Whilst the V12 is not something you could describe as
‘economical’ in absolute terms, it certainly is in relative
terms when you consider the power and torque it produces, with
real world average economy of 7.2 km/l quoted for the 2-tonne
Century. By comparison my 1UZ Supra (which weighs ~500 kg less)
gets around 8.5 km/l.
Working in tandem with
the VVTI is a variable length intake system that alternates
between two set intake lengths thereby increasing torque in the
low to mid range, which realistically is where it is of most
benefit for real world use. The boffins at Link Electrosystems
(makers of Link aftermarket engine ECUs) maintain that the
variable intake runner length has the single greatest effect on
torque delivery – even more so than variable valve timing.
Coupled with an
increased rigidity of the engine block and reciprocating mass
this results in the V12 exhibiting 10% less vibration than the
already incredibly smooth 1UZ-FE Lexus V8. Titanium coated valve
shims (operated directly by the cam) and low viscosity 5W-30
engine oil (unfortunately it holds 8 litres of the stuff)
minimize friction loss.
The V12 bore and stoke is similar to the 1JZ-GE range of
engines, although I have no idea how compatible pistons and rods
etc are. One of the Japanese tuning companies has managed to
increase one to 6 litres and add a couple of turbos; it would be
nice if 2JZ-GTE components fitted with some fettling, but it is
kind of academic for my purposes.
The all alloy 60 degree
cylinder block utilises thin wall cast iron liners that are
pressed into position, and that the cylinder bores are on a 93
mm pitch. Accordingly the V12 is actually slightly narrower than
the 90 degree 1UZ-FE V8 (but about 120 mm longer). Pistons are
also aluminium alloy and utilise a taper squish design with semi
floating piston pins.
Similar to the 1UZ-FE
the V12 utilises sintered and forged connecting rods that are
asymmetric, being dedicated for left or right bank use only.
The forged crank runs in
seven aluminium alloy bearings and has 12 balance weights.
Somewhat curiously the V12 runs a direct ignition system (DIS)
waste spark set up. Basically the front 6 cylinders have a coil
mounted directly on top of the spark plug, however, each coil
also has a plug lead pig tail that attaches to another plug,
firing in pairs.
The firing order is
1-4-9-8-5-2-11-10-3-6-7-12 with the
following spark plug pairs:
1 & 11
3 & 9
5 & 7
4 & 10
6 & 8
The spark plugs are
iridium tipped Denso SK16R11 with a 1.0 to 1.1 mm electrode gap.
Noting that the V12 runs as two independent straight 6 cylinder
engines there are two crank angle sensors fitted 180 degrees
apart to read from a common timing rotor. The rotor is a ’36
minus 2’ configuration whereby teeth are placed 10 degrees apart
(with two adjacent teeth missing) giving a total of 34 teeth.
A camshaft position sensor is fitted to the rear of each inlet
camshaft with three evenly spaced teeth placed on the timing
The Variable Valve Timing Intelligent (VVTI) system fitted to
the V12 provides up to 60 degrees of inlet cam advance when
measured in terms of crankshaft angle. This improves torque and
economy whilst reducing emissions.
The engine runs 12 cylinder sequential injection; I will
probably have to rewire the injectors in pairs as the Link is
limited to a maximum of 8 cylinder sequential injection. The
fuel system runs a standard supply and return set up, with the
normal fuel pressure at around 41 PSI, dropping to 31 at idle.
The V12 is ‘fly by wire’ or Electronic
Throttle Control System-Intelligent (ETCS-i)
in Toyota speak. This means that the
accelerator pedal has a position indicator that sends a signal
to the engine ECU. This in turn drives the two throttle motors
(remember, there are two separate throttle bodies) that open the
throttle butterfly, driving a standard throttle position sensor
along the way.
The throttle motor is also used for idle speed control, cruise
control, traction control and ABS.
Air Flow Meters
The V12 runs two independent hot wire air flow meters.
Given that the V12 only comes in one vehicle there is only one
sump location, with the bowl at the front. The sump design is
typical in that there is an alloy upper pan and a pressed steel
sump bowl. The bowl is quite wide and holds around 8 litres of
oil. 5W-30 oil is recommended. The oil filter is huge and is
apparently standard fitment on a diesel Landcruiser. I intend to
change oil every 5,000 km and filter every 10,000 even though it
is probably overkill.
The good news is the V12 runs 3 timing chains, not a toothed
belt. These probably last the life of the motor and tension is
both sprung loaded and oil pressure controlled.
The V12 runs what appears to be an air conditioning compressor
very similar to the 1UZ, mounted in a similar location.
The power steering pump is also very similar to the 1UZ unit in
both design and location with an integral reservoir, however,
some minor fittings are different.
The hose connection on the right hand side of the thermostat
housing is the water inlet (i.e. bottom tank of the radiator)
and the left hand is the outlet. The supply to the heater comes
from the Y-junction fed from both cylinder heads and the return
is the single line leading to the back of the water pump.
The radiator is
approximately 660 mm high and 900 mm wide. An electronically
controlled hydraulic cooling fan similar to that fitted to some
other Toyotas is fitted to reduce engine cooling fan noise. The
fan’s speed is electronically controlled and infinitely
variable, with the objective being to operate at the minimum
speed to cool the engine. The large hydraulically driven fans
are also capable of shifting enormous volumes of air should
cooling demand dictate.
The V12 water pump is driven off the serpentine accessory belt,
as opposed to off the cam belt like the V8.
Hydraulic Fan Pump
The Century utilises an electronically controlled hydraulic
cooling fan system similar to some V8 variants. The V12
hydraulic pump is a separate accessory item and bolts to the
engine above the air conditioning pump, as opposed to the 1UZ
variant that is integral with the front engine cover.
The alternator is also very similar to the 1UZ unit, mounting in
a similar location with a rating of 1440 watts.
The starter motor mounts on the left hand side under the exhaust
manifold and draws upwards of 2 kW. Due to the 60 degree vee
there is insufficient room to mount the starter motor between
the heads like the V8 does.
The Century underwent a minor upgrade in 2001 and it is assumed
the change from 4 speed auto to 6 speed auto occurred at this
time. The 4 speed auto is a variant of the A342E which was
common fitment to the 2.5 litre twin turbo 6 cylinder 1JZ-GTE
JZA70 supra variant (1990-1993). The gear ratios are:
Reverse is 1.880 and
differential ratio is a new style code A01A which translates to
a 3.615 ratio. Note the crown wheel diameter is 8” and standard
tyre size is 225/60R16, which is similar in overall diameter to
For the Woodie I intend
to run a 255/45x18 tyre with a 3.727 ratio MA70 Supra diff; this
coupled with a R154 (0.75:1 5th gear) gearbox will
result in similar overall gearing to the Century (2208 rpm at
100 km/h as opposed to 2183 rpm for the Century).
I am still waiting on a bellhousing to arrive (another component
my V12 was missing) however I am confident the gearbox side is
more or less identical to the 1UZ, which means my gearbox
adapter plates will fit. My aim is to run a R154 heavy duty
Supra Turbo 5 speed (which is travelling with the bellhousing)
as I suspect the W-58 Supra gearbox will be a little stretched
behind the V12.
indicates that the back of the V12 crank is more or less
identical to the V8, which means that the ‘standard’ aftermarket
flywheels will fit, as will 3SGTE units with modification. I am
also awaiting on a tilton twin plate clutch (partially used) and
billet lightweight flywheel to arrive from Australia once my
mate removes it from his car (he is upgrading his twin turbo
Lexus V8 toy to an ex NASCAR triple plate unit).
Photo Courtesy of:
Once all the components arrive I will endeavour to mate the
engine to the 5 speed and document exactly what is required in
the way of gearbox input shaft shortening and how I end up
activating the clutch (seriously considering a hydraulic release
bearing at present). The drive train will be a little bit of
overkill but the price was right for the bits and I like the
idea of it being bullet-proof.
Ideally I would run the V12 on factory engine management, but
given that my engine did not include any ECUs or AFMs my
suspicion that the cost of getting them anytime soon will be
prohibitive. Even worse, I suspect that you need to have matched
engine ECUs, anti theft system ECU and smart key otherwise it
won’t work. My other concern is that the Century employs
multiplex comms between the engine ECUs, Body ECU and
ABS/Traction control ECU; there is also a possibility that the
engine may not like it if these units go AWOL.
That said, with a bit of
luck I may be able to borrow a complete set of matched units
from another Century V12 in the next few months to see if I can
get the engine floor running.
Failing that, I have
been in touch with the techies at Link Electrosystems and it
sounds like a Link Plus G3 aftermarket ECU will run the V12
successfully. It would appear that the main issues will be:
converting the engine to
mechanical throttle operation. Looking at it I believe it will
be relatively straightforward to remove both throttle control
motors and the innermost throttle position sensor, to then join
the two butterflies on a common shaft containing a mechanical
throttle mechanism with the remaining TPS providing info to the
running only two (the most the
Link can handle) of the four knock sensors. I will probably run
an opposite pair should the need arise;
cobbling up some sort of idle
speed control mechanism. Ordinarily idle speed control is
achieved via the throttle motors, however, this won’t work with
a standard accelerator cable as there will end up being a
varying amount of slack in the cable depending on how much the
butterfly will need to be opened to maintain idle speed. My
intention is to either modify a 1UZ idle speed control stepper
motor or a rotary solenoid valve as used on 20 valve 4AGEs to
bypass air around the throttle butterflies. At this stage I
favour the stepper motor as it will probably pass sufficient
running the injectors in pairs
as the Link can only handle 8 sequential injector drives and the
V12 runs 12 sequentially;
Load measurement; my aim will
be to dispense with the pair of AFMs completely and run a
manifold absolute pressure (MAP) sensor suitably plumbed to read
from both plenums. I will also install an intake air temperature
sender (probably a generic Toyota unit) mounted in the air
shouldn’t be an issue as the link won’t handle 12 cylinder
direct fire ignition, but can handle 12 cylinder waste spark.
With a bit of luck I will be able
to commence the construction of the Woodie’s spaceframe chassis
later this year (only been saying that for the past 5 years
now…). To be honest, as much as I like the Lexus V8, somehow it
just didn’t have the appeal of being sufficiently different for
the Woodie. I always hankered for the Corvette ZR1 all alloy 32
valve Lotus developed V8, but figured I could never afford one.
I played with the idea for a while with supercharging a 1UZ, but
the V12 just has an appeal, to say nothing of what is bound to
be a marvellous exhaust note.
The 1GZ-FE will never be
a common motor simply due to the very low production numbers,
but it will definitely become more common than it is now. Prices
will most likely remain high due to a big demand and low
availability. I am unaware of any running as yet in projects,
but it is only a matter of time as several are under
One of the Japanese
tuning houses fitted a custom built 6 litre twin turbo v12
(possibly using 2JZGTE internals) to a 80 series supra and
allegedly got 1000 horsepower in road trim, which must be a
viable option should the Woodie ever feel a little slow…
Just need to get the
pesky V8 Celica project finished!
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