- When most people think of nitrous oxide,
they probably think of the Fast and the Furious movies
and think back to Brian O'Connor pulling what seems
like 15 gears along a quarter mile run that takes
about 30 seconds.
Well we're here to show you that there are some legitimate
uses for nitrous oxide outside of the movies
and drag racing.
Behind me is Tony Quinn's Highlands Motorsport part,
Ford Focus hillclimb car that competes in the unlimited
class at Pike's Peak.
Last year we found that despite the relatively small sized
Garrett GT-30 turbos fitted to the Nissan VR38 engine,
at Pike's Peak, we suffered from a huge amount
of turbo lag.
Here on our dyno at close to sea level
we were seeing full boost by around about 4000 RPM
however at the very high altitude at Pike's Peak
we were seeing a lot more lag and the turbos
weren't reaching full boost until 5000 or 5500 RPM.
Now particularly in the centre section of Pike's Peak,
this was really hurting the car as there's a lot of very
slow first and second gear switchback hairpins.
The driver would go to full throttle and it would take
as much as a full second for the turbos to reach
full boost.
After analysing the problem we decided to fit a small
nitrous kit to the car for the 2018 running
of the Pike's Peak International Hillclimb.
Nitrous works by injecting oxygen straight into
the intake system where it makes its way into the cylinders.
By chemically adding additional oxygen,
we can then add additional fuel,
this results in a larger combustion charge,
and produces more power from the engine.
With a turbocharged engine,
it also has the added benefit of producing increased
exhaust flow and this helps spool up the turbo chargers,
bringing them on boost much faster.
In order to make a full bottle of nitrous last one run,
we're using the nitrous solely for anti lag,
and this is all controlled through the Motec ECU.
Now I'm going to explain exactly how that works.
Let's start though by talking about the components
of the nitrous system.
This starts right at the back of the car with the 12 pound
carbon fibre nitrous bottle.
The carbon fibre bottle is not a particularly common choice
but it does save a lot of weight compared to
the conventional aluminium bottle.
It's mounted at the rear of the car simply because
this was one of the few places where there was enough
space to mount the bottle securely and safely.
Moving forward from the nitrous bottle,
we have a nitrous filter.
Now this just makes sure that the very small nitrous
jets aren't going to be blocked if there's any foreign
material or debris in the nitrous system.
You can also see that there is a pressure sensor
fitted to the nitrous filter inlet and this is connected
up to the Motec ECU.
This particular sensor can read up to 2000 psi.
I'll talk more about why we've got that in a moment.
Moving forward from the nitrous filter,
we move up to the Cheater solenoid,
this is a NOS product,
and this is what the ECU activates in order to actually
spray nitrous into the engine.
Because the VR38 runs two inlets with twin throttle bodies,
we've had to T the nitrous feed off that solenoid
and we're running two individual nitrous jets.
Now this system is what's referred to as a dry nitrous
installation where we are only adding the nitrous itself
through that solenoid.
When we inject the nitrous however,
we do need to add additional fuel to maintain
a safe air fuel ratio.
We're also going to potentially need to retard the ignition
timing as well.
This is all handled seamlessly through the Motec's
nitrous control strategy.
Around the nitrous bottle you can also see we've installed
a bottle heater.
Now this is just like an electric blanket
for your nitrous bottle.
The idea here is that the heater heats up the nitrous
gas inside the bottle in order to achieve and maintain
a consistent pressure in the bottle.
It's really important to try and maintain a consistent
pressure in the bottle to ensure that you get
optimum performance as well as consistency
out of the nitrous kit.
The nitrous system is all controlled electronically
via the Motec M150 ECU.
Starting with the bottle heater,
the ECU is monitoring the bottle pressure,
and via the Motec PDM or power distribution module,
the ECU can trigger a power supply to the heater
to turn the heater on until the bottle reaches
its optimum pressure of approximately 950 psi
or 65 bar.
Once that pressure's achieved the ECU then tells
the PDM to switch off the power to the nitrous heater.
The nitrous heater control is used both prior
to a run up Pike's Peak as well as during the competition
run itself.
The ECU also has a range of parameters that define
when the nitrous will actually be injected into the engine.
And we can use these to make sure that the nitrous
only sprays exactly when we want it to.
In this case we're using trigger points for both
throttle position and engine RPM.
We're limiting the nitrous flow so it will only inject
when the driver is above 90% throttle
and the engine RPM is above 3500.
For our anti lag strategy,
we also want to then switch the nitrous off
as soon as we reach a preset boost level.
Now unfortunately we couldn't actually do this
with the standard Motec package
and we had to get a little creative.
In this case because the car's also fitted with a Motec
C125 dash, we created a user condition inside the dash.
This user condition looks at our manifold pressure,
and we've also set it up to look at the driver boost
position switch.
This is a rotary switch that the driver can use
to select the boost pressure setting.
This allows us to deactivate the entire nitrous system
at the lower boost pressure settings
and also deactivate the nitrous control once
our boost pressure has reached our target.
Now we're sending the result of this user condition
out to the Motec M150 ECU via a CAN message.
So with the interaction of the Motec M150,
and that user condition in the C125 dash,
we've got complete control over exactly when the nitrous
activates and deactivates.
The aim of this strategy is to only inject nitrous
when the driver goes to full throttle,
but doesn't have sufficient boost.
As soon as the nitrous is injected,
the engine will produce more power,
more exhaust gas and this very quickly spools the turbos.
As soon as the turbos come on boost,
the nitrous can then be deactivated,
and this means that the nitrous is only active
for a very short period of time when the driver
goes back to full throttle,
out of those tight, low speed, hairpin corners.
We've got the car strapped down on our Mainline
dyno now, so we're gonna jump in and get the system
up and running.
We've completed the configuration and tuning
of the nitrous system and the results are in line
with what we were hoping for.
Here with our facility being close to sea level,
we're not seeing the true potential or advantage
of the nitrous because we didn't really have problems
with lag here in the first place.
The true potential of the nitrous system is really
going to show when the car heads to Pike's Peak
next year.
The main aim of our tuning exercise here
was simply to ensure that the fuelling and ignition timing
were safe when the nitrous system was activated.
In order to show how the nitrous system affects
the boost response though,
we have performed one run where we've activated
the nitrous a little earlier than
we intend to at Pike's Peak,
at just 3000 RPM.
Here on the dyno you can see that the boost comes
in earlier and we're making approximately an additional
25 kilowatts at the wheels through the mid range here.
Now that might not sound like an impressive figure,
but we're expecting the effect of the nitrous sytem
to be magnified at the 14000 foot altitude of Pike's Peak
and in turn this should add up to a significantly
faster run.
We're looking forward to seeing how the car performs
when it competes next.
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