Modified Magazine's review of
the Nissan 350z Twin Turbo kit
Once the turbos, exhaust manifolds
and turbo piping are mounted to the engine it
is ready to go back in the car with the transmission.
The radiator, core support and steering shaft
are buttoned back up and the massive FMIC is bolted
into place. Once the turbo compressor piping is
connected to the inlet side of the FMIC and the
FMIC outlet joined to the intake piping with 3-inch
silicone hose, the front bumper and bumper support
brace can be re-installed.
APS designed the FMIC to fit with the front bumper
support brace, maintaining full OEM front impact
protection features. Flexible ducting connects
the two cold air intake filters to the turbo intake
piping and the supplied brackets ensure that they
maintain their intended location underneath the
headlights. Finally, the stock transmission cooler
is relocated to the front bumper support brace
to make room for the passenger side intake.
Fuel Supply
More air plus more fuel equals more power. In
order to compensate for massive amounts of extra
air supplied by the twin Garrett turbos, more
fuel is required. After removing the upper and
lower intake plenum the stock injectors can be
easily replaced with the drop-in quad orifice
directional pattern injectors supplied in the
APS Twin Turbo kit. These injectors flow 500 cc
at 4.0 Bar (58 psi) differential fuel pressure
and each of these are capable of sustaining 100
horsepower (flywheel) while maintaining a 12.0:1
airfuel ratio. That's enough fuel for 600 flywheel
horsepower!
Differential pressure is the critical yardstick
when discussing injectors in forced induction
applications. As boost pressure increases inside
the inlet manifold where the injectors are situated
(lower half of the intake manifold the fuel rail
pressure must also increase proportionally in
order to maintain a constant pressure difference
across the injector orifice. This is called a
constant differential pressure fuel system. Less
sophisticated fuel systems may not employ a constant
differential pressure fuel supply. These are called
constant fuel pressure systems and were only ever
intended for naturally aspirated applications.
APS supplies an advanced injector-wiring loom
in the upgraded fuel system in order to avoid
cutting and soldering of the original injector
looms.
The stock fuel pump assembly is located behind
the passenger seat and removed for slight modification.
In order to ensure precise fuel pressure delivery
at high horsepower levels, a 4.0 Bar fuel pressure
regulator replaces the stock 3.5 Bar unit. A vacuum
line is run from the engine bay to the APS fuel
pressure regulator which is vacuum/pressure referenced
to the engine's intake manifold. The regulator
is then mounted on the outside of the stock fuel
pump/sender unit – and housed in a custom high
flow housing assembly. In this way, fuel pressure
across each injector orifice is maintained at
a constant level regardless of the turbocharger
boost pressure level - a configuration found in
the world's best turbocharged production engines.
The restriction caused by the stock 3.5 Bar regulator
is removed completely and a new custom replacement
plug is included to facilitate this. The APS custom
high flow regulator housing is safely bracketed
on the top of the stock fuel pump/sending unit
and therefore no cutting of the stock sheetmetal
is required.
Engine Management
If left alone the stock ECU would not know what
to do with all the extra air and fuel available
to it. In order to put the extra fuel and air
to use, APS enlisted Unichip of North America
to handle fuel and ignition timing. The Unichip
piggyback module is a solid-state computer about
the size of an MP3 player that comes pre-programmed
with an 8.5 PSI map claimed to be good for 400+
rwhp. By including a plug-and play adaptor to
the stock wiring harness, the APS kit eliminates
the need or splicing into the stock harness associated
with many piggy back engine management solutions.
One item of interest is that the
end user cannot tune the Unichip piggy back module
and it can only be tuned by a certified Unichip
tuner. While this may frustrate the hobby tuners
out there, it is undoubtedly safer for the average
enthusiast to seek the services of a trained professional
tuner when attempting to adjust the fuel and timing
maps.
APS 350ZTT DRIVING IMPRESSIONS
Wow. This is what I wanted the 350Z to be from
Nissan, a linear improvement on the Z32TT. With
a 120 rwhp bump in power and a 122Ib-ft gain in
torque, the already torquey VQ35 supplies power
on demand throughout the RPM band. At 3500 rpm
there are 60lb-ft more torque than stock and 100
more at 4000 RPM.
Unlike the Z32 there is little if any delay in
throttle response or "turbo lag", the
power is just there whenever you want it! The
only downfall with all this new torque is that
a heavy foot will produce gobs of wheel spin and
smoky burnouts off the line. Even having Volk
SF Challenges wrapped with super sticky 275/35YR19
Michelin Pilot Sport PS2s, wheel spin through
first, second and into third requires nothing
more than a 2500 rpm clutch dump.
From a roll the extra power kicks in quickly
and the 350Z really stretches its legs without
gasping for air like it did in stock form. I took
the car to the drag strip and the APS TT kit paired
with Mickey Thompson ET Street Drag Radials produced
a 12.44 with bracket-winning consistency at the
NOPIX-Box event in Alabama.
There's not much more to say about the APS Twin
Turbo kit other than you have to experience the
thrill ride yourself!
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2004-2005 AutoTech Engineering