[TECH TALK] How the pros tune for high altitude | LS Powered Hill Climb Car


One of the biggest advantages
of modern EFI systems is their ability to monitor
atmospheric conditions, and make changes to both
fuel and ignition timing to cope with those changes. Now, this is obviously really important when we’re at an event like Pike’s Peak International Hill Climb, where we’re climbing up a hill that peaks at over 14,000 feet. The atmospheric pressure at the summit of Pike’s
Peak is incredibly low, and this means that there’s
less oxygen available in the air, and this affects
the way the engine performs. So we took the opportunity to grab Adam from Smart EFI aside, He’s the tuner for the Enviate Hypercar, and I wanted to take the opportunity to just discuss with Adam what
tuning changes he’s making based on that high
altitude at Pike’s Peak. So first of all, Adam, can we just go over what the hardware for the EFI system in this car is, so we know
what we’re dealing with? Yeah, we’re actually doing
something really basic, so we started with a
Haltech Elite 2500 ECU, and we actually ended up using
the Haltech LS engine harness that they manufacture, that
basically just lay on the motor, and then we added to that to
add our additional sensors. The car is set up so that
we can monitor shock travel, shock velocity, wheel
speeds, steering angle, clutch pressure, brake
pressure, you name it, we pretty much wired it
so that it can be there. At this point in time,
we’re actually monitoring very little of that, we’re
doing basic engine changes, so we’ve got, obviously,
manifold pressure, exhaust back pressure, turbine speed, and that’s basically-
Lambda as well? Lambda of course, yeah, sorry. And we have a Haltech
dual-channel wide band on it, so we’re utilizing that and
it’s working extremely well, giving us really accurate measurements, so that’s been really,
really great to work with. Obviously, using components
that are all manufactured by the same company,
generally makes it much easier for the whole system to work together, and you fight that a lot less. Now, what are the challenges you face when you perhaps tune a car
like this at low altitude? I mean, we’re here in Colorado Springs, we’re still at about
2000 meters in altitude, but what challenges do you
face when you’re tuning a car at relatively low altitude
and then it’s going to compete at much higher altitude at Pike’s Peak? When you’re tuning at
altitude versus at sea level, a lot of people think that
fueling is the big difference. What we’ve learned is that
actually isn’t the truth. When you have a proper VE model, and it’s, modeled correctly with accurate data, so that the math is
actually correct, then, when you actually go to altitude, yeah, there is a fueling change, because the air density changes, but it’s not as significant
as people think. We’re actually only seeing
a seven percent increase in fueling at the the
peak versus at the base, the summit, the starting
line, for this race. So just to go back on that,
so you’re actually increasing the fueling by seven
percent from where you start at the base of the hill
climb to the summit? Correct, yeah, which is counterintuitive. You would think that you would
need to decrease the fuel, but, and in theory you would, but in reality, what we’ve found, is that that’s not the case. It actually requires more fuel. So we actually added
seven percent at the peak, versus what we were at at the base, and what we also found was at the base, the percentage difference from sea level, was only about three to four percent. So it really surprised
me, this is my first time up here on the mountain, and I, obviously, came into it with an expectation, and the mountain has taught me a lot. So, excited to be learning that. That’s interesting, because as you say, that’s definitely
counterintuitive, obviously, as you go up in altitude,
the air density decreases, so you would assume or think that less fuel would be required. I’m just interested to delve into how you’re applying that correction to the VE or the fuel map, how you’re applying that correction as the car goes up towards the summit. Yeah, so, right now, we
use an external sensor on the engine for manifold pressure, and we’re using actually
the onboard Haltech sensor for the ECU to measure barometric pressure as we go up the mountain. What we’ve found is basically, I just have a percentage
change on barometric pressure for the VE curve, and
it’s been really accurate, so what we did was, up at
the top of the mountain, I just made a baro change and linearized down to where we were at the base, and just checking it
every day to make sure it’s where I think it should be, and it is a fairly linear change, which is what I expected
for pressure changes, but, I think my belief is that
the air temperature change coming out of the turbos
because they’re working so much harder at altitude to
make the same boost pressure is why we have to add fuel. So I believe what the issue is, that’s making me add this change is that, the air temp correction is not quite where I wanted it to be, but that’s one, something you really can’t
discover at sea level unless you put the car
into those situations. I think that’s one of the things that a lot of people overlook
with these modern ECUs, even though we’ve got
very advanced fuel models on the likes of the Haltech Elite ECU. We are still talking about an ECU that is applying a generic fuel model that’s supposed to be accurate enough to work on thousands of engines, so it is likely that there will be potentially some discrepancy creep in, and the fuel model may
not be 100% accurate across the board, would that
be a reasonable thing to say? Uh, yeah, for sure, and
a lot of it is also that, you know, if you look
at an OEM calibration, they test those calibrations in so many different environments. We’re so limited on what we can do because of the time constraint. They spend thousands of
hours calibrating an engine, we’re spending a few, you know, at best, and sometimes 10, 20, you know, we have obviously a lot of work into this calibration up here, but, it’s little bits in
comparison to what an OEM ECU is capable of doing, and it’s
not that it’s not capable to do it, it’s the amount
of time that it takes to build that model
from nothing, you know. Standalones, they don’t have
the stock map out of a car, you start from nothing, and you have to build your
maps from scratch, so, we skip steps, really, I mean, to put it bluntly, we
skip steps to save time and to meet the needs that we’re facing because we don’t always tune cars that go all over the planet, we generally tune for one environment. Now, just with those
discrepancies in the fueling that you’re talking about, and I mean, even if we’re competing
at a fixed altitude, maybe at a race track,
it is typical to see small discrepancies in the air fuel ratio from one lap to another as some
of the operating conditions vary outside of the conditions we saw when we tuned it, and a common technique to combat that, those small
variations that we’re seeing, would be to use closed loop air fuel ratio or lambda control. Is that something you’re
using on the Enviate Hypercar? Yeah, definitely, a lot
of people are scared of closed loop O2 control, they’re worried that it will overshoot or undershoot and put you in conditions
that you wouldn’t foresee. We logged the change that
the controller is making, and then I make my adjustments to the map based on that, and then watch
the trims change lap to lap. Like I said, first day when we got up to the top of the mountain,
it was adding eight percent, so I put seven percent fuel in the map, and bam, my trims were at one percent. So that’s how I knew what to do. The ECU does all the work for you and you just read the data out and say, “Okay, great, here’s the change,” and you have to figure out
where the most effective place to make that change was. I knew the VE map was
correct at sea level, so obviously changing the
VE map isn’t the answer. You have to change a correction, so barometric pressure made
the most sense at the time. Now that we’re running at
the base of the mountain, and seeing more conditions and
seeing how the car develops, in hindsight, maybe, barometric
pressure isn’t perfect, but it definitely has a lot to do with it, so there are definitely
different varying factors that you have to consider,
and you just decide what’s the best change for
your application at the time. Now, when it comes to a turbo-charged car running at higher altitude,
and there’s the argument that, in terms of the fuel requirements, manifold pressure is manifold pressure, and the absolute manifold
pressure is really the key element that the ECU needs to know,
but another side effect that is probably often overlooked is, as we go up in altitude, the
barometric pressure drops. If we want to maintain a fixed
manifold absolute pressure, what this means is, we actually have to drive
the turbo chargers harder, they’re working at a higher
pressure ratio and in turn, this increases the exhaust
manifold back pressure. So how do you see the exhaust
manifold back pressure playing into your tuning? It’s actually a big effect. What we’ve found is, we needed
more power on the mountain than what we needed at sea level. The car wants more, as we
get the chassis dialed in, the driver wants more, so
we keep putting more boost into the engine, and
obviously as we do that, as we command more boost duty,
the back pressure increases. So you’re fighting that balance, you know, as boost pressure goes
up, back pressure goes up. What we’ve actually found
is that our turbine housings are too small up here, so when we went to make 20 pounds of boost
on this engine, we couldn’t. You could put 100% boost duty in there, and all you see is the drive
pressure just skyrocket. You don’t actually get
any more boost pressure, you just get tons of back pressure because the waste gate won’t
let any of the pressure out of the exhaust, and it
actually ends up hurting power. A lot of people don’t realize that, when you run out of efficiency, if you just keep asking for more, you’re just gonna hurt your goal. So what we’ve decided is, we’re gonna try and get some new back housings on it to be able to be more efficient and allow us that headroom so
we can make more power up top. Just while we’re talking
about the turbo chargers, you’ve also got turbo
speed as an input, so, what relevance is that to
you when you’re looking at the data, how you’re using it
to help you modify the tune? Yeah, so, obviously as we
increase waste gate duty, that increases drive pressure,
which increases drive speed. Especially at altitude,
where the air is less dense, the turbo charger has to speed
up to make the same amount of pressure that we’re commanding, so we’re obviously commanding more duty, which is more drive pressure,
which is more speed. Unfortunately, there’s a really
fine line and balance there, but what a lot of people don’t realize is, you can really push the turbo chargers harder than you’d expect,
and they’re really robust, especially the newer units,
they’re in really good shape. We have Garrett Gen2s
on the car right now, and they’re really,
really stout, so, to me, turbine speed isn’t a huge concern, as long as we’re not
fighting back pressure. You have to be smart
about what you’re doing, but overall, the turbine speed
is just kind of what it is, and we’re just monitoring to make sure we’re not working the
turbo chargers too hard. They’re pretty happy, right now, at about 16 pounds of boost. We can squeeze 18 or so out of it, but again, your drive pressure goes up, your turbine speed goes up a ton to make that extra two pounds of boost, but in this car, two pounds
of boost is 150 horsepower, so it’s a big change. All right, let’s just
talk a little bit about the data that you’re looking
at when the car’s running on the mountain and
particularly, in practice, we’re very limited on the timeframe, so, can you talk me through the
process that you go through when the car comes back from a run? Yeah, so, obviously you’ve
been on the mountain. It’s really stringent
as far as timeline goes. We get on the mountain at
about 3:30 in the morning, and we have to be off by
9:30 in the morning, like, not just packed up, but
off the mountain by 9:30. So that really gives us a six-hour window to not only unload the car,
prep the car, race the car, and to get the car back in the trailer. So between runs, when
we bring the car back, the first thing I do is
straight on the laptop, connect to the ECU, pull the
data out, and view the data. For me, with the stringent timelines, because I know that the engine is healthy, and I know basically where we’re
at as far as the tune goes, I’m really quick with it,
I look at oil pressure, oil temperature, and coolant temperature are my biggest priorities. A lot of people don’t know about the mountain’s strenuous
activity on your cooling system. It is the biggest, hardest item for people to tackle up here, the air is really thin, it’s hard to get enough
airflow across your radiator. We actually have two on the car and about three and a half
gallons worth of fluid. So, a really really high capacity system that still fights cooling issues. I’ll just go into that a little bit deeper just sort of for those of our listeners who don’t really understand
what that means, so, while the lower air density
means that the engine is struggling to make power,
that lower air density also affects the ability
for us to dissipate heat out of the radiators,
out of the oil coolers, so that, coupled with the fact that, for a lot of the course, Pike’s Peak’s actually
relatively low-speed, so, you’ve got the engine
working incredibly hard, high RPM, sustained high RPM, but relatively low vehicle speed, so you’re not getting that
airflow across the radiator, so it’s sort of a perfect
storm of a situation that really adds up to
make a cooling system that works perfectly at sea
level really really struggle. That’s what you’re finding? Yeah, absolutely, and I think a lot of the teams struggle with it. But we were really fortunate to overcome our cooling issues on day one, so we went up on the mountain, we found some issues
with our cooling system, we came back and addressed them, but that’s always the one
thing that you’re looking for because, oil pressure, oil temperature, and coolant temperature
are the three things that will really ruin your day. If you have a boost leak,
you can go back and fix it, and if you have a cylinder down,
you can go back and fix it, but if your oil temperature
goes to 350 degrees, that’s gonna ruin your day, you know. Same thing with oil pressure falling off or coolant temp going
crazy, so that’s the thing that we’re most cognizant about, is, make sure that the car is healthy enough to go back out for another run, and then everything else is secondary. So after I get through
those three pieces of data and make sure that we didn’t
increase, go over our limits, and our targeted areas of where
we wanted to be in the tune, we look at, obviously, engine
RPM, where was the driver at? And as far as, in the power
band for most of the run, what was the average engine RPM, we’re looking at manifold pressure, how much did it make, did we
make more boost than we wanted, less boost than we wanted,
right exactly where we wanted? What was boost duty cycle
doing to achieve those numbers? And then obviously check the widebands and the knock control. It seems like a lot, but I
go through it really quickly, obviously with knock data
it’s usually really apparent with, you have a knock event, so, you can look at that really briefly and if you don’t see a knock event, move it out of the way and
move on to the next thing. And just talking about that, so you’re running on a Sunoco 118 octane, which is a petroleum-based fuel, it’s not an alcohol-based fuel, so this engine on that
fuel is still knock limited at nine to one compression? It’s not, not that we’ve found. So, we run it really conservatively. I know that there is a knock limit. We haven’t been there,
we look at the plugs fairly frequently to make sure that we’re where we want
to be on the tune-up. We’re probably three or four degrees down from the peak timing value that
we could put in the engine, but obviously longevity is
priority number one at this race. We can make all the power in the world by just throwing boost at the engine, so, conservative timing keeps it alive, and we run with that theory that, be conservative, be easy on it, and it will last all
the way up the mountain. Just one last thing that I
wanted to touch on as well, is you’ve obviously got a lot of ways with this particular car
given the adjustability and the suspension and
also the aero package. You’ve got a lot of ways of
improving its performance. You can make adjustments to suspension, you can make adjustments to downforce, or you can also make adjustments to the power the engine’s producing. Do you find that there
is one specific area that’s really the key,
is it engine performance or is it chassis
performance, when it comes to getting those improvements, or do they all have to
really go hand-in-hand? They really go hand-in-hand. Obviously, without the
chassis set up properly, you can make all the power in the world, and not put it down,
and it does you no good. But with all the chassis in the world, if you don’t have any power,
you can’t get up the mountain. It’s not a downhill race,
it’s an uphill race, so you need power and torque to do that. So it’s a fine balance, we work on all of it at the same time. It’s really a mad scramble
with very little sleep. This mountain definitely tests, not only the car, but the team. Do you have the mettle to see
it from day one to day ten? It’s a really long week,
really testing the car, putting it through its
paces, but, you know, you have to balance, you
have to talk to the driver and see what the driver wants, and you have to talk to
the chassis people and see, is it pushing, do I need more power here? We’ve done a lot of adjusting, actually in the low RPM ranges. What we found was, going into the turns and coming out of the
turns, we were slowing down so much that the engine
was dropping out of power and just didn’t have enough torque to accelerate out of the
turn the way we wanted to. So we basically went
into that low load area where we’re not making really much boost, and really low RPM and just
threw a ton of timing at it, to wake the car up there, and the driver’s really happy with that. It’s an orchestra. You’ve gotta, you know, get
everybody to play together, and everybody’s playing the same tune, and you get a successful project, and so far, we’ve been really successful and we’re really happy with were we’re at. I think that is an area
that is often overlooked, and people tend to think they
can focus on just one aspect, their engine performance or the chassis. So, as you say, you really
need everything working in harmony to get the
best possible results. Well, look, it’s Thursday
here and you’ve completed the second day of practice
on the middle section of the mountain and despite
a severe ignition misfire, Which had the engine I think
running on five cylinders? Yeah, five cylinders.
You still put in, second fastest in the unlimited class, so that’s a pretty impressive
place to be on Thursday. Thanks for the chat, Adam,
and we really look forward to seeing how the car progresses and what it can do on Sunday. Really appreciate it, and really glad to talk to you guys about it. Thanks.
Thanks.


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