- These days there's no shortage of Nissan GT-Rs pushing 2000, even 3000
horsepower but of course all of that power is useless if you can't get it to the track.
And this is where managing the power delivery or the torque delivery
is so critical.
So we're here with Tony Palo from T1 Race to talk about how that's
managed in the Motec M150 ECU.
So Tony the more typical way of managing torque in a turbocharged car
is really by adjusting the boost targets and often this is done as the car
goes down the track.
Now with the M150 package it's quite different in the way the ECU actually
works in that it's what's referred to as a torque based ECU.
So can you tell us what the differences are between a torque based system
and a conventional ECU?
- Yeah so almost any new car on the road now is a torque based system.
It offers a lot of advantages.
Whatever the reason is that you're limiting power or torque,
it all boils down to torque, whether it's the engine or transmission failing,
or traction, it all comes down to torque.
And so if we can maintain torque flat to redline, we can have a lot more
horsepower than a typical torque curve that just peaks and falls.
So the M150 for the GT-R incorporates a full torque based strategy that works
really well.
So that'll control throttle and/or boost to meet your torque limit.
So that torque limit based on gear, speed, driver switch, whatever you want.
- Now one of the reasons that is critical even in a relatively modest power GT-R
is because the torque needs to be modulated for the transmission to shift
is that correct?
- So there's different things, so we control torque under power,
typically just for traction.
Or if it's, we're knock limited, maybe we're on 93 octane and the turbo
could make a lot more.
But then there's also the torque reduction strategy that has to happen on the shifts.
So the way it works on these is the TCM sends a request for torque reduction,
and we have the option to fully listen to that request and obey that request,
or at higher torque levels when we're making more torque than the TCM
is kind of programmed for, then we take over to a full M1 strategy on that.
So we'll use the TCM request in full at lower torques so drivability's just
like stock, and then at higher power we have a threshold above 500,
800 foot pounds of torque, we go to a full M1 based strategy that is initiated
by the TCM requesting and then it's all on board in the M1.
- Now in terms of the tuner's aspect, this sounds like it could be quite complex
tuning all of the associated data or tables related to that so does that make
it any more difficult or is this all handled automatically in the background
by the Motec?
- It gives you more control.
- Sorry I'm talking about more in terms of does tuning the actual engine,
so fuel and ignition strategy, so when you're actually on the dyno,
do you need to tune a torque table to tell the ECU for a given throttle
position or boost pressure versus RPM, how much torque the engine
is actually producing, or is the ECU calculating or modelling that
in the background?
- It's calculating and modelling all that.
So it's primarily looking at your engine displacement and your volumetric efficiency.
It assumes you're at MBT so if you've got 10 degrees of timing out of it
and it's making a lot more torque than it thinks you're making,
there are compensation tables that you can go in if you find that the dyno
doesn't agree with this, maybe the V table's off a little bit, whatever it is,
you can make it as right as you want.
For most cars, as long as you're keeping torque reasonably flat,
everything's gonna work well.
It's not super critical that it's accurate to 50 foot pounds.
Because we're not doing this going oh I know I can't go past this number.
So if it's working well and it's within 30 or 50 pounds, it's gonna work the same
as if it wasn't.
- I'll just elaborate on what you talked about there for those who maybe,
that's new to, so MBT timing so that's where we're making maximum torque.
So the ECU, in this case the M1's, just assuming that we're always at
MBT timing and a lot of OE applications that use torque modelling,
they'll actually have a modification to the torque that's calculated based
on how far away from MBT timing we are.
So in this case that's not happening in the M1 as you say,
not really essential for the way you're using it.
So once it's actually tuned, once you've go the car off the dyno,
let's talk about some of those advantages with the torque based ECU.
So how are you then manipulating the torque output as the car goes
down the track?
What access have you got, what control have you got over that?
- I typically do torque by gear because the reality is the second that gear
changes, you've changed the torque to the tyre and you can have more boost.
And gear recognition is something that happens instantly on these.
So as soon as it changes gear, it shoots up to new torque limit.
Assuming you were reducing torque for traction.
It'll control boost, when you're going down the track it's always gonna be
boost control, you're at high enough boost.
I set 'em up, launch control and traction control are always active.
If I'm not at full torque and it's not spinning, then it needs more, right.
So I want it to be touching traction control here and there in every gear.
- When you're just coming into that traction control just very slightly
it means you're right on that limit of the available traction?
- Sure, if you're not spinning and you're not at full power, the car can go faster.
- Now in a lower sort of power application as well you've mentioned the fact you've
got the ability to use boost and or throttle control.
So obviously if you're in a position where you're already below the minimum
wastegate spring pressure, we can't use boost control to drop the boost any further
so this is where the throttle control strategy comes in.
So can you talk to us about how that works?
- So you're gonna be 100% on the pedal and the ECU will, you'll have your
torque limit and as torque approaches that, it'll just roll back the throttle
to maintain torque there.
A typical, this car for example makes 1500 horsepower.
I can run it at 700 foot pounds of torque and it'll be at 15% throttle position
at higher RPM but it'll hold it nice and steady.
- Look it's really impressive the advances we've seen in these aftermarket ECUs
and obviously this is why we're starting to see these cars go faster and faster.
So thanks for the time to give us some insight into how that all works
and we'll let you get back to tuning, thank Tony.
- Cool thanks.
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