- When it comes to selecting ECUs for an aftermarket engine management project,
there's a wide range of options and of course all of those options come
with a vast range of price points.
Now of course there's also different feature sets that go with those different ECUs
and this can be a little bit frustrating and confusing for the average enthusiast.
Of course the sort of ECU that we may choose for our street car project is going
to be quite different to what we may want to choose for a high end professional level
of motorsport but we've got Martin from BM Technik here to just talk us through
some of those options and find out what we're actually getting for our money
when we're laying down perhaps USD$10,000 plus for an ECU.
So I guess Martin to start with, talking about the feature sets from an ECU,
I think it's important to understand that when we're looking at a different ECU
feature set, if we've got an ECU that lists that it has traction control,
that doesn't necessarily mean that every traction control strategy works in the
same way.
Can you talk us through a little bit about the differences you see between different
brands and how that transpires when you've actually got a car on a damp surface?
- Well one of the biggest differences between entry level ECUs and high performance
ECUs is the one box solution, you get much more packed into one device.
The datalogger sits on top of it which is important to always know what the strategy
does at each individual time.
Not just to get the raw data sampled fast enough but also what are the process
steps in between.
That is one major difference and just the complexity of embedded systems in a
high performance ECU is by a factor of 100 different to more simple ECUs.
- Actually you just mentioned there about datalogging and I think we'll come back
to that traction control issue but just because you've mentioned the datalogging
there, and again this is an area where an ECU will say that it's got datalogging
capability and on face value that may seem to be enough but of course depending
on what you're doing, you may need more channels which takes up more memory
and also the speed that we're able to log different channels is really important.
Can you tell us about how that works out in professional motorsport and what you
actually need?
- Datalogging systems, just the name datalogging doesn't mean the functionalities
are identical.
High performance ECUs nowadays are capable of logging 100s and 100s of
channels at a very high rate.
So modern ECUs like a Cosworth ECU are capable of going up to 200 kilohertz
nowadays.
They can capture data in an aperiodic way, they can capture data very fast
and very synchronous to each other.
That's something a lower entry level ECU would not be capable of.
- Now you just mentioned 200,000 hertz so what that means is you're able to
capture a certain signal 200,000 times a second.
Now of course you don't need to capture every signal going into the ECU
at that speed.
Some of the slower moving signals such as perhaps air temperature and coolant
temperature, probably we're quite capable of logging that at a low frequency,
maybe two to five hertz.
But of course when you start looking at things like maybe in cylinder pressure,
this is something that's happening very fast and to get that data in a useful format,
this is where those frequencies are important?
- Correct, absolutely.
So there are things like damper movement, in cylinder position sensors or cylinder
pressure sensors where having such a high rate is critical.
- Now just because we've talked about or mentioned there, in cylinder pressure,
this is something that we again don't see at the entry level, club level, street level,
it's just not something we use for tuning but of course at professional motorsport levels
and OE levels, this is how the engines are calibrated.
So normally this is a tool that's only used during the dyno session and it's monitoring
the actual pressure inside the combustion chamber so we can see exactly where
peak cylinder pressure is occurring, helping us to optimise spark timing
as well as make sure we can see if detonation or pre ignition are occurring.
But now some of these aftermarket ECUs at high end are able to also do this
on the fly, is this correct?
- That's correct yeah absolutely.
Even in a professional realm and I have to say it's not that easy to get the
sensors or to get the business case and get it justified to have this equipment on board.
The amplifiers and the sensors can be really expensive.
Monitoring eight cylinder engines where you need eight of them is,
it collects to a lot of money.
But having access to these sensors is, what you have is you have the final
puzzle piece of being really closed loop.
Normally more or less, your fire orders, at a point where you think you shoot fire,
you throw in an amount which you think should be alright.
You have sensors like the lambda sensors sitting behind it where you can have
a bit of an idea of what happened.
But having access to the pressure curve itself is something, you actually see what
is going on at which crank angle and position.
- Now for me it's of interest there, if you've got this data on the dyno,
that's one thing, as I've said you can use that for calibration which is fine but if
you've now got ECUs that have the ability to monitor this in real time on an eight
cylinder engine for example, is it then possible to use strategies to provide
essentially closed loop control of the ignition timing?
In other words, adjusting the timing on the fly as the engine's running to make sure
that each cylinder is always achieving optimal timing?
- That is possible.
There is a lot of strategies which can be derived from having this information.
There are strategies for basically engine wear detection, there are strategies
for knock control, there are strategies to basically work out how equally balanced
each cylinder is to each other.
You can compensate for different views, there is a lot of compensation
you can run it with.
Actually having access to a closed loop real time ignition control method
is like the most sophisticated thing you can do.
What it is in general, without going too much into detail is basically equalising the
mass fraction burned points at a certain spot.
So rather than having them jumping around and having effects like remaining exhaust
within the cylinder which affects the next cycle, you can compensate for these
effects and always get the optimum performance out of that cycle,
out of that moment.
- Now I think it's also worth mentioning here that the cost, which you've kind of touched on
there of the sensors and integrating those sensors into the engine,
if you're looking at applying that to your engine, probably the cost of the ECU is
the least of your worries.
So this, just so everyone viewing this is aware, this is a very expensive system
to add to any engine.
Now just talking about some of the other strategies there, when you're talking about
an ECU that is used at the highest levels of motorsport, perhaps LMP1 LMP2
for example, what sort of strategies are being used there that we don't see
at club level motorsport that can be useful to getting the last little bit of performance
out of an engine and out of the chassis?
- The complexity of the strategies is big nowadays compared to where they are
10, 15 years ago.
As I mentioned before, having a single box solution where one ECU is running
not just the fuelling and the ignition but traction control, knock control,
transmission control, pit lane limit control full course yellow control,
everything which is logged.
AXON displays are driven off ECUs nowadays as well, they are just sitting there as a
satellite remote display.
So while configuring the display or with the display setup,
the ECU does all that work.
So there's a lot going on within a single device, there are thousands
of parameters, thousands of channels.
If you want to hear about an example, talking about, I think you mentioned
traction control earlier, where simple traction controls only more or less
looking at a percentage of absolute comparison of the undriven and the
driven wheel speeds.
Things like grip estimation can be added where you're actually forecasting
the grip levels under certain conditions.
In combination with using different pedal maps, so basically the translation
between your pedal sensor and the fly by wire actuators sitting in the front
of the engine.
It's so much linked into each other, you wouldn't find this on
an entry level device.
- So it sounds to me like you're talking more about preemptive or predictive
traction control rather than actually dealing with the situation once the
car is wheel spinning, is that correct?
- Yes that is correct.
- And of course if you can keep the car hooked up and keep traction,
it's going to make the car easier for the driver to control and when we're not
wheel spinning, you're able to get maximum acceleration, is that fair to say?
- Yes so maximum acceleration is one of the reasons why you would add it
but also in general I always look at the traction control as a performance item
but also as a health insurance.
We're doing a lot of work in the endurance racing and with endurance racing if you
think about being at Nurburgring 24 hour at 4 o'clock in the morning doing a triple stint,
you want something which always does the job.
When you're coming into slippery, greasy, raining conditions,
you want something which reacts very quick, helps you in every situation.
Having something where just the sudden change of the wheel speed,
what in a PID, the detune would help you with, everything is tuned to perfection
and would help you under these conditions.
- Look Martin, been great to get some insight into what goes into an ECU at
that price point and hopefully that's given our viewers at least a little bit more of an
idea of why these ECUs are priced at that level.
Obviously not suitable for every application but if you've got a pretty big cheque book
and you're racing at those levels, it's going to give you an advantage.
Now if people want to reach out and find out more about you and your company,
where can they go to?
- That would be bmracetec.de or martin@bmracetec.de,
I'm more than happy to answer questions and to help with any enquiries.
- Perfect, thanks a lot for the chat.
- Thank you, no problem.
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