- When it comes to getting stable accurate boost control, the wastegate technology
that we've been dealing with in the aftermarket is now pretty established.
And Turbosmart have long been one of the leaders in the aftermarket.
It's not often that we see a new innovation in this market but Turbosmart here at SEMA 2019
have release their new range of electronic external and internal wastegate actuators.
We're here with Chris to find out a little bit more about these wastegates.
Now Chris, I'll actually take a step backwards here because I did just mention that this
is a new innovation.
Let's just talk about the elephant in the room because I know a lot of people will be saying
well hey, OEs have been doing this for a while now and that is true.
How does the Turbosmart solution differ from what's in the OE world at the moment?
- Alright so the OE applications are usually designed for a fairly optimised package
and they never really run excessive boost pressures, or they might for the high
performance market but they're designed for that particular application.
Now in our industry, say for example drag racing, we can be running upwards of say
60, 70 psi worth of boost and these actuators are usually found in internally actuated
wastegates so when you've got a lot of drive pressure on that, you've got a lot of force
acting on that flapper and these actuators, they don't hold a position, they always need
a current supply to hold them in a particular position and they back drive as well.
So what I mean by back drive is if you apply a big enough force, the motor can't
provide the holding torque and it just moves from its target position.
- Alright let's just back up a little bit there, you talked about boost pressure,
60, 70 psi, but as far as the wastegate's concerned there, and that back driving
that you're talking about, the part that's easy to overlook for most enthusiasts
is that we also have a hell of a lot of back pressure in the exhaust manifold.
So you've got boost pressure in the inlet manifold, it's not uncommon, particularly
for some non optimised turbo packages to see the exhaust manifold back pressure
as much as double the inlet manifold pressure, so that force is trying to push
the wastegate open and you've got to deal with that correct?
- Correct, exactly right.
So for example in our test car, we've got an EFR 6258.
We run about 34 psi in the manifold, trying to max out that turbo
and we can see over 55 psi in the exhaust.
- So it's that back pressure that you're trying to fight so you were just saying there that
the OE applications, obviously they're not dealing with the performance world,
they're just making an actuator that's designed for that factory application,
obviously it's going to work well there but once you start increasing the boost
pressure, seeing the exhaust manifold back pressure rise, essentially you can see a situation
where those OE actuators can just be forced open?
- Correct, definitely and that's even true on the OE application tuning so for example,
guys using standard ECUs and reflashing them, they get so far with the boost
now in these hybrid turbos that the standard actuator can't even hold its
target position.
- Alright so let's also talk about why you've made the decision here to go to an
electronic actuator.
Obviously you've been making pneumatic actuators or mechanically actuated
wastegates for a long time now, the technology's very well developed.
Where are the advantages with the electronic control?
- So electronic control basically gives you complete freedom, you can map your boost
irrespective of what boost pressure the turbo's trying to make.
Sorry, you can map position, so if you want to open the wastegate for whatever reason,
you can open it, you just command a position or a boost and you can try and achieve that.
- Are we talking the ability for these electronic wastegates to open and close
faster than a conventional wastegate as well?
- Look really the conventional wastegates, the rate of open and close is dependant
on your pressure that's going to be seen in the canister so if you've got really high
pressure, well of course they're going to close really quick, but if you've got a low
pressure, you're fighting that spring as well so you might be in a situation where
the electronic actuator could be quicker but in another case, if you're feeding it
200 to 300 psi, something silly, well the mechanical actuator will close very quickly.
- Now that's another point that you've just touched on there as well that conventionally
with a normal wastegate if we want to make a wholesale change to our boost,
obviously we've got a range of boost control but if we want to make a large change to
our boost, probably also entails changing the base spring pressure so that we're getting
within a range where we can get good control.
Of course with the electronic control, wastegate springs, thing of the past,
don't need those.
Any boost is available basically depending on the capability of the turbo?
- That's right I mean you can run basically the limit of the system, equally you can run
as much boost as a turbo can provide safely.
And likewise you can run as low boost as you can provide as long as your
wastegate path is designed properly and you've got enough bypass capability.
- Alright so let's talk about the control strategy here.
The electronic actuator itself is quite a large unit and you've designed this to be
able to handle that immense back pressure, as you were just saying before,
something that the OE actuators may struggle with.
The problem we've got of course is we in the aftermarket, need a way of actually controlling
this so can you talk us through what the control strategy is for the electronic
actuator, what inputs and outputs we're going to need in order to actually
make it work.
- Alright so at the moment, we're collecting some feedback from aftermarket
ECU manufacturers as well but on its bare bones, essentially the motor has a two
pin drive for output, so that'll control the motor and then we've got an onboard
encoder which is feedback in position.
So to control it, at the moment we use a PWM signal and basically we convert the
PWM signal which otherwise would be a boost bleed on the solenoid,
to a target position.
So for example 75% bleed on the solenoid could be 75% of its max lift.
And then basically we will map the boost table which is your bleed as a target
position to control boost.
- Alright so essentially very similar to the likes of a drive by wire throttle body where
you've got position feedback and you're using something like an H bridge controller
in the ECU to actually drive the servo motor to open and close the
throttle body?
- Exactly right, you've just got a feedback for position and then a H bridge drive.
- Now there are some aftermarket ECUs out there already that are able to control
the likes of some of these OE electronic wastegate actuators.
There's some problems though potentially with those crossing over to the
Turbosmart, can you talk to us about the current handling capabilities?
- Yes so given the large force constraints we're dealing with, with these I guess
high performance aftermarket applications, there's no point in us introducing an
actuator that's just going to have the same problems as historical past.
So given that situation you can have a rising current.
Now at the moment, we have rated the actuator to be a 20 amp continuous drive.
We have done that from a safety perspective.
That's at its worst case condition.
So usually operating in a, I guess, transient state trying to control boost,
we'll be under that 20 amp threshold, it could be even less than 10 amps.
So some ECU manufacturers out there do have the capability to drive it as is.
They will be pin limited based on that package though.
- Now when you say pin limited, I mean obviously there's not a standardised
aftermarket ECU connector but the AMP Superseal is just one that springs to mind
because it is so common and with the AMP Superseal pins, you're sort of current
limited to a little bit under sort of 10 amps or thereabouts so what's the solution there,
can they use multiple pins?
- That's right, I believe, look this would be up to the ECU manufacturers really
to answer, I can't speak for them on their behalf but I mean look we've been
getting some feedback at the moment and it seems to be possible based on the
current configuration they have.
- Alright so in terms of other control strategies, is it something where
Turbosmart could look at developing your own standalone controller that then could be
more conventionally controlled with an aftermarket ECU with the likes of a
conventional low current PWM output?
- Yeah look I mean there's obviously many many ECUs out there at the moment and
people as of today are investing in an ECU that is very good at what it can do.
So we need to look at that and say right we want to support this as well,
because obviously they want to use the latest products that we sell so there
will be an intermediate box, basically if you like a high bridge drive that will link
between the ECU and also the wastegate as well to provide that high current.
- Alright so just coming back to the capabilities of the wastegate,
you've talked about the amount of force it can apply or the amount of back
pressure that it can withstand.
Can we actually put some numbers around that, how much force can it apply to the
wastegate valve and how much back pressure can that withstand?
- Sure so we've rated it to about 80 psi worth of exhaust manifold pressure.
Now obviously that could be more in your manifold or less depending on how
efficient your engine is.
In terms of force, that could be around 1200 newtons or 1.2 kilo newtons.
And that's in a transient state, in a stall torque situation that force drastically
goes up but we won't quote those numbers because we don't,
we shouldn't be operating in that range basically.
- Now that 80 psi of back pressure you just quoted as well, I understand that's on
your 60 mil wastegate so if you dropped down to the likes of the smaller wastegates,
that actually increases?
- Correct so if we use the same control actuator on the 60 mil and put it on
a 40 mil valve, that exhaust manifold pressure rating could be upwards of
150 psi.
- Probably safe to say it's going to be more than enough for most people.
Now the other aspect that I've seen on the stand here that's a little unique,
sort of goes hand in hand with the electronic control,
is you've moved away or got an option to move away form a poppet style wastegate
to a, essentially a butterfly style wastegate actuator or wastegate valve,
much like we see in a conventional throttle body so can you talk to us
about the advantages or pros and cons of going to a butterfly style wastegate?
- Alright so from our perspective we've got the butterfly valve that we've introduced,
I think it's going to have much more benefits over the popper valve.
So first you're going to have much better control, butterfly valves are inherently
designed to control mass flow.
So from a wastegating perspective you're going to have much better control
over what's going on in the exhaust and what's being bypassed.
Not only that, you've got a package constraint, so for a given valve size you're going to
outflow a poppet.
So we've got a 50 mil orifice butterfly valve and that outflows our 60 which is our
largest wastegate.
Having said that, on the low blade angle we've got the control of a 40 mil wastegate
as well so from the outset we've got one butterfly valve that can provide all the
solutions of our external wastegates at the moment.
Now one of the problems of course with anything that's in the exhaust system is
it's got to handle that heat.
And the way the poppet style valve works, you've got that valve seat,
so essentially as the valve heats up and the body of the wastegate heats up,
it's still going to seal, you've got an angled seat that it can basically grow on,
is that a problem with a butterfly style as the housing and the butterfly grow,
is there an issue there with trying to maintain a really solid seal when it is
closed so you've got no boost leaks?
Sorry no exhaust leaks.
- Right I understand, it's similar to the poppet valve, I mean we're dealing with
a lot of exhaust temperatures through that system.
And we've also got a valve guide there as well so we need to maintain a particular
clearance in that system and we've gone through years of development trying to
optimise that.
It's the same technology for the butterfly, we're using very similar materials as well
so we know what those rates are.
We've got experience with those materials and we've implemented that technology
into the butterfly and we're not using the
butterfly as a conventional throttle body butterfly where they don't really seal,
these have two positive stops that the butterfly goes home to seal against
at all times.
- Look Chris it's been really interesting to see something that is truely innovative
in the aftermarket boost control world and we look forward to seeing it come
out and be available to consumers.
Can you give us some indication of when that might be?
- The poppet valve should be available early next year.
- Alright thanks for the chat Chris.
- No worries, thank you very much.
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