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Nitrous
The biggest value of nitrous is its versatility. It
doesn't care what you drive or what engine you have, as long as it's installed
right it will make power. There are application-specific kits offered and
universal kits, a big plus to those who who have cars for which no kit is
available.
Burning more fuel is the only way to make more power, but to
make power in an internal combustion engine there must be a proper ratio of fuel
and air. It is the air portion of the equation where nitrous makes its impact
felt. Nitrous oxide is a molecule with two nitrogen atoms and one oxygen atom.
In the nitrous bottle and under pressure the nitrous is in liquid form. When it
is released through the nozzle it turns to gas. The act of combustion breaks the
chemical bond of the molecule, releasing the oxygen atom. By weight, air is
23-percent oxygen while nitrous is 36-percent oxygen. So there is more oxygen
present in the nitrous-enhanced combustion chamber ready to make power. When the
proper amount of fuel is introduced and sparked that's what happens--more power.
Dry Manifold, Wet-Manifold, Direct Port
There are two basic types of nitrous systems--dry manifold and wet manifold. A
dry system uses a nozzle to inject only nitrous into the intake tract. Fuel
enrichment is handled via the fuel injectors by increasing fuel pressure or
injector pulsewidth when the system is activated. A wet system injects fuel and
nitrous through the same nozzle. In conventional set-ups the amount of fuel and
nitrous injected into the engine is determined by the orifice size of the jets
installed in the nozzle. The typical system is activated by a throttle-mounted
Hobbs switch that fires the nitrous solenoid and releases the nitrous when the
engine sees wide-open throttle.
A possible drawback with a single-nozzle system is it relies on the design of
the intake manifold to distribute the nitrous or nitrous/gasoline mixture to the
cylinders. By virtue of their design or casting shifts some intake manifolds do
not distribute air evenly to all the cylinders and as the power levels of the
nitrous system increase the small differences in flow become more critical. At
best, there is less precise distribution and a tuning challenge--at worst, the
chances of creating a lean condition are increased.
The answer here is a direct-port system where fuel and nitrous are injected at
the ports through individual nozzles positioned at each cylinder, ensuring even
distribution. If you plan to run a moderate, say a 50-75 hp shot, a conventional
single nozzle (wet or dry) system will work fine. At 100 shot one should
consider the flow properties of the intake tract. The direct-port system is more
involved from an installation standpoint as the intake must be drilled and
tapped in each runner to accommodate the nozzles. Also, the port system runs a
distribution block where the nitrous is routed to each individual nozzle. This
plumbing also takes time and skill to install.
For racing and extreme street cars staged nitrous is the next step up. In this
configuration, the system provides a set amount of nitrous at initial activation
then ups the dosage when the driver hits a button. These
systems are basically two systems in one as each stage has its own solenoid and
nozzles. The basic idea is to provide the extra power when the car has the
traction to make use of it. Throwing a 250-hp shot at a front drive off the line
will only granulate rubber and stress the driveline. There are endless
possibilities when it comes to configuring a staged system. The major factors
include engine status (built, stock), traction characteristics of the car and
intended usage (street or race).
For more precise control and linear application of nitrous-enhanced power
Progressive computer control is the way to go. A computer oversees the
application of nitrous. Depending on the complexity of the system, the system's
computer can be programmed to flow nitrous based on throttle position or over
time. Throttle position progressive systems use TPS voltage to calculate when to
start the flow. So at, say 2.5 volts, the nitrous begins to flow as voltage
increases so does the flow until WOT where the full capability of the nitrous
system is unleashed. Time-based progressive nitrous control allows the user to
select the percentage of initial flow and program the amount of time it will
take for the system to reach 100 percent flow. The range is 0-10 seconds. So 30
percent can be selected as the initial flow and the system can be programmed to
attain 100 percent at 4 seconds.
A more advanced time-based set-up allows the user to really micro-manage the
flow of nitrous. This system allows the user to program the percentage of
nitrous introduced and when said percentage is introduced and increased. For
example, in this scenario 25-percent of the system's capability can be brought
on-line at 0 seconds, 50 percent at 3.5 seconds, 80-percent at 5.6 seconds and
100 percent at 6.9 seconds.
There are also spool-up kits for turbocharged engines. This type of system is
designed to provide a moderate amount of nitrous until a pre-determined boost
level is attained. The nitrous adds power but more importantly adds to the
amount of exhaust gases which gets the turbo up to speed quicker. When at the
specified boost the nitrous kit hands the baton of power over to the turbo
system.
Engine Upgrades
For the basic 40- to 60-hp dry system no engine mods are needed. It would be
wise to run premium 100-octane fuel and reduce the gap of
the plugs. The fuel system should be checked to ensure it is in good working
order. For some engines a colder plug may pay dividends.
As the power potential of the system goes up so does the need for engine
improvements. More power is generated by burning more fuel; nitrous provides the
extra oxygen need to "release" the power. So as the power increases somewhere
down the line the fuel system will have to be upgraded.
A byproduct of nitrous oxide is increased cylinder pressures which is why the
plug gap should be closed in basic kits. As power goes up so does the internal
cylinder pressures so at some point the ignition system will need to be
upgraded. The power expectations of the nitrous system and the performance of
the particular stock ignition will determine when an upgrade is called for. Some
nitrous systems may also require timing retard. The heat generated by nitrous
can have an adverse effect on the exhaust valves and in some cases the pistons,
which may need to be upgraded by way of stainless-steel valves and forged
pistons. As with any performance engine, big power potential requires a built
bottom end.
Installation Quick Tips
Each manufacturer has its own instructions but here are some basics that are
universally applicable:
The nitrous bottle should be installed in the trunk with
the valve facing the front of the vehicle in a downward position with the valve
outlet aimed at the floor. The bottle should also be tilted with the valve end
higher off the floor. This is done to ensure the pick-up gets all the nitrous
possible.
The nozzle in non direct-port applications should be placed four to six inches
before the throttle body. This is done to ensure there is proper atomization of
the mixture prior to its entering the combustion chamber. Some nozzles are
directional designs that need to point in the same direction as the airflow into
the engine.
Do not use Teflon tape in the fittings. The tape can be sheared off and blown
into the solenoid where it can hinder the solenoid's operation and result in a
lean condition and possibly catastrophic engine failure.
Be wary of ROM-tuning or adding performance chips to a nitrous engine. Nitrous
likes retarded timing and chips or ROM tunes that advance timing can cause
detonation or worse.
Nitrous works best at maximum or near maximum bottle pressure. One way to keep
the pressure up is to install a bottle warmer, most manufacturers offer these as
optional equipment.
Check your fuel filter and replace it if needed. Fuel sediment can hurt the
performance of the solenoids and/or clog the jets in wet systems.
Purchase a tube-bending tool like the one NOS offers. It will save time, ensure
proper connections and make the install look cleaner.
Running the nitrous system continuously can be harmful
to the engine. At the most hit the button for 10 to 15 seconds at a time.
Nitrous is a potent power producer that hits hard from a performance standpoint
without the steep cost of general power adders. It is a transparent
technology--when not in use a nitrous system has no effect on the drivability of
the car it's installed on. Furthermore, nitrous can be made to work on just
about any engine. With the advent of computer control a properly installed and
tuned system is a reliable avenue to power and performance.
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