- As long as chassis dynos have been in existence, the age old debate has
always been how does power at the wheels relate to power at the flywheel?
For example is it 10% or 15%?
Does that drive train loss stay the same if your engine's making 500 horsepower
or 1500 horsepower?
Well the cart behind me has been built by Mainline dyno to answer those
exact questions.
The basis of this cart is the DIY chassis kit imported from the USA,
and then modified in house by Mainline to suit their requirements.
It's been fitted with a Brodix 632 cubic inch cast iron block and topped with a pair
of Brodix heads and a Hogan sheet metal aluminium inlet manifold.
There's nothing particularly special inside that engine, however it is built with
some top line equipment and designed to support in excess of 3500 horsepower.
In particular the compression ratio of the engine has been selected at a
relatively mild 9:1 allowing the team at Mainline to test this engine on a
variety of different fuels, including pump gas, E85, and methanol.
Providing air flow into the engine is a pair of Garrett GTX 5533 turbochargers,
mounted on a set of PAC Performance built exhaust manifolds,
with boost being controlled by a pair of Turbosmart external wastegates.
Probably the most standout feature of the whole car though is the fact
that the engine as well as the Rossler Turbo 400 transmission,
are both mounted on gimbles.
What htis means is that the engine and the transmission are both supported
inside the chassis on a gimble that rotates on bearings front and rear.
This allows a load cell to measure exactly how much torque is being
produced at each location through the chassis.
So with a load cell on the engine, a load cell on the transmission,
and then of course a pair of load cells in the dyno itself,
this allows the torque and hence horsepower to be measured and
calculated at each of those points at the rear axles, at the transmission,
and then also at the engine.
And this is how Mainline are going to answer that question as to exactly
what sort of drive train losses you do see on a chassis dyno.
When it comes to data and sensors, our personal philosophy is the more
you've got, the better, and Mainline clearly agree.
This car is running just about every sensor known to man.
Starting with the most obvious, we can see that there are a lot of exhaust gas
lambda sensors fitted to the engine.
In particular there is one exhaust gas lambda sensor fitted to the header
or exhaust runner on each cylinder, allowing for individual cylinder
lambda readings.
These all run to what appears to be one of Todd's fettishes, the Autronic air fuel
ratio meter.
He's got a lot of them.
On top of this there's also a pair of lambda sensors on the outlet of the turbochargers.
Now there are a few intricacies and a few tricky bits when it comes to measuring
exhaust gas lambda pre turbocharger.
The exhaust gas lambda reading is skewed or affected by exhaust gas
back pressure.
So this is why you can see there is also exhaust gas back pressure
pre turbocharger and then of course post turbocharger as well.
While the Autronic air fuel ration meters are used for the individual cylinder
lambda readings, post turbocharger, one of the sensors is a Bosch LSU 4.9
lambda sensor going directly into the Emtron KV16 ECU.
The other is an NTK sensor that is running into a Motec dual lambda to CAN module.
The intention with this system is that Todd and the Mainline crew will be able
to compare the accuracy and the readings from different lambda sensors.
In particular in the exhaust headers, you can see there is an unused port
at the moment allowing that comparison to take place.
A little bit trickier to see, on the underside of the exhaust runners,
is a set of exhaust gas temperature sensors.
Now this is what a lot of tuners rely on traditionally to adjust individual
cylinder fuel trimming, although really this is a round about way of deducing
the air fuel ratio.
So it will also be interesting to see the comparison between the individual
cylinder lambda and the individual cylinder exhaust gas temperature.
Moving forward to the turbochargers, there's a lot of data and sensors around
these too.
Starting with the turbo speed sensor, this will be helpful for deducing exactly
where abouts on the turbo compressor map the compressor is running.
Pressure and temperature at the outlet of the turbocharger is also being measured,
and this allows the pressure ratio the turbocharger's operating at to be
accurately measured, as well as being able to calculate the adiabatic efficiency
of the turbo compressor.
Once that hot air exits the turbocharger compressor, it runs into a water to air
intercooler.
Now this is oversize with the massive supply of ice water that allows it to remain
consistent and cool that temperature over an extended dyno session.
By measuring both the pressure pre and post intercooler as well as the
temperature pre and post intercooler, the efficiency of that intercooler
can be accurately calculated and measured.
While the dyno cart has initially been developed to run on the Emtron KV16 ECU,
there is a Milspec connector that allows a variety of ECUs to quickly be plugged
in with just the construction of a basic jumper harness.
In the future, Mainline intend to run the dyno cart on a Haltech and just about any
other ECU that they're interested in testing out.
With so many sensors on this dyno cart, collecting and analysing the data
is obviously a major factor.
In this case a Motec C1212 dash logger has been fitted and this comprises a central
logging hub.
Data is collected directly from all of the sensors as well as taking data in from
whichever ECU is fitted via a CAN data stream.
This allows all of that data to be collected in one single place,
making it really easy to analyse that data regardless which ECU
is fitted at the time.
With the complexity of the Mainline dyno, all of the data from the Motec
C1212 dash can also be output and analysed and viewed inside
the Mainline Dynolog software while the dyno cart is running on the dyno.
With a relatively complex setup, a lot of things going on, a lot of electrical
circuits to control, a Motec PDM or power distribution module has been fitted.
Now this is essentially a solid state relay or a set of solid state relays
that allows really flexible and specific control of the power distribution
to all of the required circuits.
This is incredibly used friendly as well because all of the functions that the
PDM is in charge of can be controlled via a simple CAN based keypad,
that's mounted on top of the dash.
The dyno cart is incredibly close to being up and running, and once it is,
we're gonna be heading back across to Sydney to have a go on it ourselves.
With the potential to make close to 3500 horsepower,
we're certainly excited to have a go and we're also really interested to see
some hard data and some facts on that relationship between flywheel power
and power at the rear wheels.
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