- Under Suzuki's Scorch Racing Nissan S15
has always been a crowd favourite
here at World Time Attack Challenge.
Until now though there's been very little information
out there about what makes this car tick.
We've taken the opportunity to get an in depth
tech tour of the S15.
The turbo charger is one of the key aspects
of any of these Time Attack cars,
and in this case the Scorch Racing S15
is fitted with one of the new Garret GTX3584Rs.
This uses a v-band exhaust housing
with a single scroll inlet.
The boot control is via a turbo smart external wastegate.
And heat control here is a major issue.
You can see that the team have built a guard
around the turbo charger to control the heat
in the engine bay.
And this results in a lot of heat being placed
into the wastegate.
In particular this can result in problems
with the wastegate diaphragm rupturing.
So the team have actually plumbed a supply of fresh air
directly from the front bumper,
straight onto the head of the wastegate in order to cool
it and make sure that it remains reliable
in the heat of battle.
On the inlet side of the engine,
there's a hypertune intlet plenum fitted with a set
of Injector Dynamics ID2000 injectors
to supply the E85 fuel that the engine runs on.
In order to make sure that the engine remains reliable,
under the extremely high lateral g forces
that these cars are pulling,
a full dry sump lubrication system has been fitted.
This takes the engine oil and extracts it out of the sump
and it stores it in a remote reservoir.
An external pump then sucks the oil from the reservoir
and pumps it back through the engine.
This ensures that regardless of the acceleration,
braking, or cornering loads,
a constant supply of high pressure oil is always available
to the engine.
A change this year to the drive train has been made.
Previously the car ran the older Holinger RD6
six speed sequential gear box that is manually actuated
by the driver.
For this year the team have switched to the later model
Holinger paddle shifter gear box,
which is actuated via air.
The driver now can change gears both up and down
using paddles on the steering wheel.
The up shift is completed under full throttle,
the clutch isn't needed after the car leaves the pits.
In order to actuate the up shift,
the Motec ECU cuts ignition momentarily
to allow the next gear to be engaged.
On the down shift a throttle blip is done automatically
via the Bosch drive by wire throttle body
to match revs for the next lower gear.
Another change for 2017 is to the electronics package
on the car.
Previously running the older Motec M800 ECU,
the team have now swapped to the new generation
Motec M150 which is running Motec's GPRP,
or general purpose race paddle shift package.
This controls the engine as well
as the paddle shifter gearbox.
The driver display is via a Motec C125 dash which keeps
the driver up to date with what's happening,
including the Motec shift light module,
this is also the central logging location,
where all of the logged data from the engine
and chassis can be extracted.
A Motec PDM30 and CAN based keypad
is also included to replace the traditional fuses
and relays that we'd normally find on a car.
The Motec PDM30 is a solid state power distribution module
which controls power distribution
to all of the engine's vitals,
as well as the other electronic components on the car.
Every year we see the power levels at World Time Attack
increase and for 2017 the Scorch Racing team
have also added a 200 horsepower shot of nitrous.
Now traditionally the nitrous systems at World Time Attack
have been used either right through the rev range,
or alternatively as an anti lag measure to help spool
a really large turbo.
The Scorch Racing team are using it in a slightly
unique way.
With the Garrett GTX3584 turbo charger
being essentially at its limit,
the team are enabling the nitrous flow above 7500 RPM
when the driver's at full throttle.
And this helps top up the power at that higher RPM range
right up to the engine's 9500 RPM limit,
and helps extend the power band of the engine.
The nitrous system is managed by the Motec M150 ECU
so it can be programmed to bring in the nitrous
based on gear, engine speed,
and the driver's throttle position.
Now when the nitrous system is active,
additional fuel is required to meet the additional oxygen
that's being injected by the nitrous oxide.
This is handled in two ways,
first of all the nitrous system here is what's referred
to as a wet system.
This means that nitrous oxide and fuel
are both injected via the nitrous nozzle,
fitted pre throttle body.
The Motec M150 ECU can then be used to trim
the fuel delivery as required in order to ensure
that the air fuel ratio is exactly what the team wants.
Now with a light two wheel drive car like this,
despite the high down force from the aerodynamics on the car
traction is always an issue.
And this is where power management is very critical.
In this case the boost is controlled via the M150 ECU,
based on gear and throttle position.
This ensures that the amount of power that the engine
is producing can be accurately mapped
to the amount of traction available from the track.
This means that in low speed corners,
where the car is heavily traction limited,
the boost is lower,
and this makes it easier for the driver to control the car.
Of course even with these strategies,
traction control is still vital,
and here the Motec M150 provides an advanced
traction control strategy where ignition and fuel cutting
can be used to control engine torque,
and manage any wheel spin that does occur.
Aerodynamics is understandably a really critical part
of any of the pro or pro am class cars
here at World Time Attack.
Scorch Racing have been working closely
with Andrew Brilliant from AMB Aero
over the last four years they've been competing
here at World Time Attack,
and each year small improvements have been made
to the aero package.
As you can see the entire outside body of the S15
is now carbon combined with a large front splitter,
as well as that large rear wing,
and the rear tunnel diffuser in order to optimise
the down force as well as the aero balance from the car.
Certainly this S15 is always one to watch,
and we admire Under Suzuki's commitment,
building this car and developing it,
essentially as a one man team with some of his friends
back in Japan.
We wish them all the best for the rest of their event
here at World Time Attack.
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