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Tech download: Tricks of the trade in IndyCar fuel saving

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emailBy Stan Sandoval | January 19, 2023 10:34 AM ET

After discussing why teams will resort to fuel saving in the last column, the natural follow-up question is, how do teams go about doing this? While there are many strategic reasons that teams will turn to fuel saving during a race, in every scenario teams will try to save fuel in the most efficient way possible. That is, minimizing the lap time penalty as best they can while still hitting the fuel target.

How teams go about minimizing their lap time loss when needing to save fuel depends on several factors: the capability of the engine manufacturer to run different engine modes, the ability of the driver to adapt their driving technique, as well as the characteristics of the track and the current traffic situation. Engine manufacturers, teams, and drivers will work together and spend huge amounts of resources to optimize this aspect of performance, be it on the dyno, in simulation, or during track testing. The ability to save fuel without losing much time can be a huge differentiator throughout a race.

There are two primary techniques for saving fuel: the driver can either change engine modes, or incorporate lifting and coasting. Each has their own advantages and disadvantages, but they effectively achieve the same thing: completing the lap while saving fuel compared to running at 100%. Deciding the most efficient way to use one or both of these techniques over an entire lap however, is very difficult. Oftentimes, there are an infinite number of ways to hit the same fuel target, so teams will set about using the engineering tools at their disposal to find the best approach.

Engine modes

Changing engine modes is relatively straightforward. The engine manufacturer can load various settings into the car’s ECU, which can then be selected by the driver by adjusting a dial on the steering wheel during the race. Doing so will effectively (and without giving too much away) reduce engine power and fuel consumption in lockstep.

When it comes to fuel saving, this is where the battle between manufacturers lies. Offering reduced fuel consumption for the same power compared to the competition not only gives teams additional race pace when hitting the same fuel target, but also opens up the number of strategy options available to them.

Since fuel targets can change throughout the race, teams will always ensure there are multiple options available on the dial, each with its own compromise of power reduction and reduced fuel consumption. Teams will also use data from practice sessions to advise over the radio as to what engine mode should be used for a given fuel target. With engine modes, the driver can continue to push with their driving style while still saving fuel. Typically, when resorting to changing engine modes, acceleration is the biggest compromise to performance (though there is also an effect on top speed) due to having less power available. On the plus side, drivers can continue to attack brake zones and corner entries and they normally would.

Lift and coast

The most common fuel saving technique for a driver is ‘lift and coast.’ As the driver is nearing the end of a straight and approaching a brake zone, they will lift well before the normal braking point, coast without any input on throttle or brake for some distance, and then apply the brake when sufficiently close to corner entry.
Alexander Rossi showed just how effective the lift and coast approach can be at Indy in 2016. F. Peirce Williams/Motorsport Images

The idea is that fuel consumption is closely tied to being on-throttle, so if a driver needs to reduce consumption, they will have to lift for some amount of time during the lap. Lifting towards the end of a straight is ideal because this is when the driver is closest to top speed, so they will coast farther, and therefore save more fuel. Additionally, a car is accelerating much less at the end of the straight than it is at the beginning (since acceleration begins to taper off the closer the car gets to top speed), so lifting at the end of the straight is also less penalizing on lap time. Therefore, the higher the entry speed into a corner, the better it typically is to use lift and coast to save fuel.

The main benefit to lift and coast is that there is no de-tuning of the engine: acceleration for most of the straight remains the same as it would when not saving fuel. However, the detriment to lift and coast is quite clear: all the time loss is concentrated at corner entries.

Comparing fuel save methods

To get an initial comparison between approaches, engineers will turn to a vital tool called lap time simulation. This is a software that will use a numerically modeled car, track, and driver to solve physics equations as a way of creating data for a virtual lap as if it really happened on track, but with the benefit of every single parameter being controlled by the engineer.

Lap time simulation is a hugely complex subject in its own right; one that can do everything from investigating potential setups to predicting the effect of changing ambient conditions. It is one of the most important pieces of software an engineer will use. For the scope of this article though, it allows the engineer to compare fuel saving approaches to see whether changing engine mode or lift and coast is the fastest way to hit a fuel target.


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Starting with the most basic of examples, a simulation of accelerating from the apex of one corner, down a straight, to the apex of the next corner is modeled. Running at 100% burns 0.301 gallons, but say the fuel target is 0.286 gallons (5% savings). The engine manufacturer – who has been doing some work on the dyno – says that they have three engine modes to try. The first is full power and full consumption (Mode 1), the next offers 4% power reduction for a 5% savings in fuel consumption (Mode 2), and the final option offers 8% power reduction for 9% fuel savings (Mode 3). Lap time simulation can be run iteratively in order to solve for the required lift and coast distance until the fuel target is achieved. Mode 1 is going to require 135 ft of lift and coast to hit the fuel target, Mode 2 will still need 50 ft of lift and coast, and Mode 3 can be run without any driving adjustments needed to be made. With these simulations, overlays of speed, fuel consumption, and lap time (plotted versus distance) can be compared to a push lap with no fuel saving, and the results can then be analyzed.

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Move your cursor over the graphs to reveal additional details



In this example, all three fuel saving approaches use the same amount of fuel, but using Mode 1 and 135 ft of lift and coast is 0.23s faster than going straight to Mode 3. That is a massive amount of time for just one corner! Also of note, using Mode 1 and 135 ft of lift and coast is only 0.02s than pushing flat-out, which is hardly any loss time at all for using 5% less fuel. When done efficiently, the lap time loss from fuel saving came close to nothing.

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Tricks of the trade in IndyCar fuel saving

Gavin Baker/Motorsport Images
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emailBy Stan Sandoval | January 19, 2023 10:34 AM ET

Optimizing for lap time

The idea of simulating potential fuel saving approaches can be expanded from a basic example of just one straight to simulating an entire lap, but doing so brings additional complexity. Distributing where the driver lifts and coasts throughout the lap increases the number of simulations by several orders of magnitude. Putting aside engine modes for this example, say that at a (fictional) street course with five corners, a push lap burns 0.742 gallons and the fuel target is 0.668 gallons (or 10% reduction in consumption). Now, the driver wants to know where the best places to lift are and how much should they be lifting in each corner. Is it faster to only do one big, long lift on one straight to save the entire 0.074 gallons in one go? Or should the driver do smaller, shorter lifts throughout the lap adding up to 0.074 gallons saved in total? Once again, lap time simulation is an engineer’s best friend. These simulations can run hundreds of thousands of laps at the click of a button, and then data analysis software can immediately point to the best solutions. Below is a typical sweep of various lift and coast distances for each corner of the track.

Move your cursor over the graphs to reveal additional details



After using lap time simulation to create this data, finding the combination of lift and coast distances in each corner that can stay under the fuel target while also going the fastest is now a straightforward data analysis problem. Code can be written to create theoretical laps for every combination of lift and coast distance in every corner (that’s 16,807 laps in this example!), and the fastest approach that hits the fuel target will become apparent. In this sweep, the engine mode has been fixed and only one fuel target has been given. But in reality, both of those parameters are also variable during the race and so the amount of pre-event simulation done by the teams and manufacturers in the weeks building up to a race weekend can become enormous, as they have to be prepared for all possible scenarios.



The simulations say that when fuel consumption is reduced by 10%, the lap time loss can be anywhere from 0.121s when done optimally to 1.678s if done inefficiently. Since fuel saving simulations like this are so important and are used week-in and week-out, teams have typically developed software and code to automate these tasks to immediately solve for an ideal approach.

Also from these results, something else that has already been touched on (but can now be seen in the data) is that the higher the entry speed, the better suited that corner is for lift and coast. From this, it follows that the fuel saving characteristics of each track are different from one another. Tracks with long straights and big braking zones (like Nashville) tend to be more suited for lift and coast, whereas tracks with shorter straights and flowing corners (like Barber) tend to prefer using engine modes.

Traffic and track position also plays a big factor in how teams save fuel throughout the race. Thus far, fuel saving has only been discussed through the lens of optimizing lap time. But for a track like Nashville, the end of the two long straights are also great overtaking spots. If a driver needs to save fuel but also defend their track position, a big lift and coast at the end of each straight leaves them vulnerable to being passed. In these situations, drivers will do their fuel saving in parts of the track where overtaking is impossible, like the back section of Nashville from T4 to T7. While this certainly isn’t ideal for lap time, it does allow the driver to hit the fuel target while giving them the best chance of maintaining position. The optimum fuel save approach will always depend on how much fuel needs to be saved, but the characteristics of the track and traffic are just more variables for drivers and engineers to consider as they hone in on a best solution.

The driver

A deeper look at these overlays can also begin to show why resorting to lift and coast requires a change in driving style, and why some drivers are better at it than others. Adding a lift at the end of the straight obviously lowers the entry speed compared to pushing at 100%, so drivers can actually brake later when doing lift and coast and still achieve the same apex speed. This means that braking is done over a much shorter distance when saving fuel, which changes the required peak brake pressure and the bleed-off technique that should be used. Because there is only a finite amount of tire grip to be allocated for both braking and turning, the knock-on effect of changing braking technique is that the steering technique to rotate the car on entry changes as well.
The most effective drivers are able to stretch their fuel with virtually no penalty to their lap time. Joe Skibinski/Penske Entertainment

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The reason for this last segment being slightly shorter is that I was over the character limit by 283
and that necessitated a "pit stop" so to speak, to pause, and split the last article segment into two pieces...for a total of three segments.

If I did better character management, I would have typed a slightly shorter article, and finished sooner...with only one pit stop
mid way to adjust article length.

The person who is still typing after I have finished had divided his article into 4 segments to be sure he would have enough space remaining
.............but he required an extra pause/pit stop and he ultimately took longer because of that pause.

So what is the trade off? Type slow enough that you can count the characters and finish with barely space left, or
make an extra pausing pit stop which costs you even more time.
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article resumes under the above line.......
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In fact, the driving style through the entire entry phase to the corner changes when doing lift and coast: switching from a late braking, aggressive style towards being more ‘efficient’ in the way drivers simultaneously slow down and rotate the car in order to scrub off as little speed as possible. There is no fuel saving done whatsoever from apex to exit, so despite having to change the way they approach the entries, drivers need to be sure that minimizing time loss on entry doesn’t compromise the exit phase. Depending on a driver’s ability to adapt their style, some teams are better off using engine modes for the same fuel target that other teams might choose to lift and coast. Ultimately, each team is going to do whatever is fastest for them.

As fuel targets often change throughout the race, lift and coast distances (and thus entry speeds) will also change. Drivers that can adjust their style the quickest are at a huge advantage in these situations. If strategy dictates going directly from pushing flat-out to a massive amount of fuel saving, a driver that takes a couple of laps to settle in to such a big shift may lose heaps of time to drivers that can adapt at a moment’s notice.

Driver consistency can also make a big difference. Once a lift and coast distance is determined, a new braking point is found, and the driving style has adapted accordingly, being able to repeat this every time gives a competitive advantage over drivers who may struggle to drive the car the same way each lap. Consistency is obviously beneficial in many aspects of driving, but when it comes to minimizing losses from fuel saving, it becomes even more critical.

Finally, a driver being good at fuel saving isn’t dictated purely by their driving technique. Before each race, engineers and drivers will review the best combination of engine mode and lift and coast distances in each corner for a series of possible fuel targets. Once a fuel target is called out on the radio, the driver should know what engine mode and where/how much lift and coast to do. Still, when adjusting to a new fuel target there is always a period of feeling it out. In the heat of the moment, drivers with the ability to recall the most efficient approach to save fuel for a given fuel target can gain time on drivers that might need a couple of laps to arrive at the most efficient approach through experimenting, or drivers that may require some coaching on the radio.

All this to say, drivers can have a huge effect on race pace when fuel saving. The best drivers can save fuel and minimize their lap time loss to the point that they are almost as fast as they are when pushing. It is truly impressive to see how drivers can adapt their braking points and driving style on a moment’s notice and then consistently run lap after lap without fault.

Running it dry

There’s an old adage in race car design that because of the compromise between speed and reliability, the perfect racecar takes the checkered flag and immediately falls apart.

Ultimately, any fuel left in the car at the end of a stint is a performance loss. That fuel is weight that was carried around the track for a whole stint to eventually serve no purpose. When this happens, a higher consumption could have been used to complete the same number of laps. Every car in the paddock has an engineer dedicated to fuel strategy during the race: they are typically calculating and recalculating fuel targets in live time, updating pit windows as the race goes on, all in order to run the car as close to empty as they dare at every opportunity. While it may sound obvious, the best way to go fast while saving fuel is to save less fuel! Still, no sensor is perfect and so engineers will always want to err on the conservative side if they can’t be exact. Fuel left over in the tank is certainly better than running out on track.

The perfect stint means the car gets to pit lane, or finishes the race, practically dry. These engineers are playing the world’s scariest game of the The Price is Right: get as close to the perfect amount without ever going over. Run out of fuel and they’ll be out of the race, leave too much fuel in the tank and they are leaving performance on the table. While it’s not a particularly popular move with mechanics, when it comes to threading that needle, finishing the race – but not the cooldown lap – is an engineering gold star!

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Measuring Surface Grip at Texas IndyCar.

See also

https://www.tamparacing.com/forums/chassis-suspension-tech/848342-racing-lines-rubber-rain-agenda-texas.html#post9449098


The RACER Channel
58.5K subscribers6,041 views Mar 31, 2023 TEXAS MOTOR SPEEDWAY
The turns at Texas Motor Speedway have varying levels of grip to offer IndyCar drivers, and with the help of Firestone's Dan Bishop and a device they call 'Mr. T,' RACER's Marshall Pruett learns about how the low lane and the darker high lane pose different challenges to the drivers.

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Neither Kirkwood nor Rossi were at fault in Texas.

Amazing that they don't crash more often when crossing in or out of the pits.

How one organization handles it when they have space for three lanes.

Michael Levitt/Motorsport Images
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emailBy Marshall Pruett | April 4, 2023 4:22 PM ET

As IndyCar’s rules for pit lane procedures are written, Kyle Kirkwood did nothing wrong on Sunday afternoon as he attempted to turn into his pit box with the No. 27 Andretti Autosport Honda.

Alexander Rossi – the former driver of the No.27, with whom Kirkwood made contact – was also a blameless party in the unintentional incident that was triggered when he was exiting his pit box and did his best Roman Reigns impression by spearing Kirkwood.

Rossi’s race was ruined on the spot as the crisscrossing cars collided; his No. 7 Chevy needed repairs to its suspension which cost the team multiple laps. Despite being briefly slightly delayed, Kirkwood’s day was unaffected until an unrelated suspension failure took him out of the 250-lap contest.

Where heat and scrutiny began to rise with the situation was in the NTT IndyCar Series’ decision to penalize Rossi rather than Kirkwood, who was initially thought to have breached protocol. NBC’s commentators went hard against Kirkwood during the broadcast, which then led to a volley of criticism directed at Kirkwood on social media, but at least one host later apologized to the sophomore driver after getting a better picture of the situation.

As the series has instructed its teams and drivers, those in the outer lane — the ‘fast’ lane — are the top priority on pit lane when it comes to decision-making. Those in the middle lane — the ‘transition lane’ — are second on the priority list when drivers either pull away from or pull into their pit box. Last on the list are those who are in their pit box.

Drivers are also told to remain in the fast lane until it’s time to steer into their pit box; they’re only allowed to drive straight within the transition lane on approach to their pit box in the rare instance of finding some sort of blockage in the fast lane.

Otherwise, turning from the outermost lane across the transition lane and into the pit box, as Kirkwood attempted to do, is precisely what’s expected of each driver.

Whether Kirkwood did or didn’t make a late turn out of the fast lane to meet his Andretti Autosport pit crew sitting four boxes down the road from Rossi’s Arrow McLaren crew is immaterial. Unlike IMSA, which has a regulation that limits how soon drivers can start turning towards their pit box, IndyCar drivers are free to choose — within reason – when they start to turn out of the fast lane to make a pit stop. Considering Kirkwood’s late and sharp turn-in point, which happened after Rossi dropped the clutch and kicked his car sideways in his pit box with smoke pouring off the rear tires, one can see how a mistake could be made on where the No. 27 was headed.

Despite being unable to see each other from the confines of their open-wheel race cars, Kirkwood followed all of IndyCar’s rules for pitting, and accordingly, was not penalized. And Rossi followed the instructions from his team to engage first gear and fire out of his pit box after service was complete, but was deemed to be a rule-breaking instigator.

Their collision, a surprise to both parties, was initially attributed by the series as a breach of Rule 7.11.1.10, ‘unsafe release of a car from its pit box’, which led to a lap 62 drive-through penalty for Rossi. It was later revised to a violation of Rule 7.11.1.7, ‘contact with another car,’ which is an interesting adjustment as the penalty gives the impression of shifting the blame from the No. 7 Chevy’s crew to its driver.

Rossi followed orders from Brian Barnhart, his car controller, and was understandably incensed when he was told to serve the penalty. It’s here where a few points have emerged that would be worth evaluation by IndyCar and its rule makers.
Kirkwood’s approach to his pit box at Texas was completely within the rules – which suggests that the rules, or pit entry procedures, could do with some tweaking. Joe Skibinski

Just as drivers have adopted the somewhat recent practice of exiting Turn 2 on ovals and weaving hard left to indicate to those who are following that they will be pitting — a signal to steer clear because they will be slowing significantly in a few seconds — it seems like a similar conveyance of information to crew chiefs and car controllers about a driver’s intent in the fast lane would do wonders to avoid future clashes.

It’s a miracle that dozens of crashes aren’t the norm on pit lane at every race. But thanks to the incredibly talented and quick-thinking outside front tire changers or car controllers who reside on the timing stands and decide when to release their drivers from the pit box, they are rarities.

Nonetheless, the person in charge of releasing their driver is asked to process an amount of information that would overwhelm most people.

In a pit stop that lasts around eight seconds or so, it starts with using the last two or three seconds of the stop to assess local information about the readiness of their car: Are all tires properly secured? Has the refueller successfully removed the fuel probe? Has a wing change been completed? Is the car on the ground and are all wheel guns and hoses clear of the car’s exit route?

Once that mental checklist is completed, the next task — done in the final second or two of the stop — involves looking up the road, judging the distance between oncoming cars and their own, trying to recall whether those cars are pitted in front or behind their driver, which is important to know as it’s used to judge whether those cars are driving out of pit lane and continuing on or are due to pull in and pit, and then, while making an assumption that those who are likely to pit aren’t serving a drive-through penalty or continuing without stopping due to being called in by mistake, the car chief or controller elects to hold or send their car.

All while the 100-plus decibels of racing sounds and other assaults on the senses must be filtered out, and all in less time than it takes to read these final few words. Multiply the number of cars entered in each race — at least 27 per round this year — and the number of pit stops per car — between four and six at Texas — and these rapid-fire calculations were performed more than 100 times on Sunday without contact. That only one car-to-car crash happened defies all odds.

In the case of the No. 7 Chevy, the team could have held Rossi for another beat or two and let Kirkwood clear their box. And had Kirkwood seen Rossi as he started to turn in, he could have tapped the brakes and waited for the No. 7 to drive off. But as he said in a post-race interview, with the narrow view out of the No. 27 Honda, Kirkwood only saw the two cars ahead of Rossi: Scott Dixon and Alex Palou.

But those things didn’t happen and we’re left to ask how some blind spots can be removed in the future.

Whether it’s a similar pit-in type of weave, provided it’s a pit lane like TMS that’s wide enough to safely perform such a maneuver, or to have the soon-to-turn driver straddle the white line between the fast and transition lanes once they get within a three or four pit boxes of their own stall, or the adoption of a Formula E-style overheard light that informs car chiefs and controllers as to whether the oncoming car has or hasn’t pitted, it’s clear that each car’s decision maker could use more visual cues to understand the intent of cars coming toward their own in the fast lane.

We just could default to the rule that gives cars in that outer lane top priority, but no team — not in a fiercely competitive series like IndyCar — is willing to surrender extra seconds on pit lane. The ability for most car chiefs and controllers to recall where their rivals are pitted from race to race and whether an oncoming car is likely to turn or go straight is another miracle that seems ripe for simplification and clarity.

Given a chance for a do-over, a no-call from IndyCar seems appropriate.

Thankfully, the vast amount of pit stops are completed without drama, but when a Kirkwood vs Rossi situation arises, it presents an opportunity to ask whether more can be done to help pit crews make better decisions in the fastest and most extreme aspects of their jobs. Start by removing the unnecessary guesswork about what the cars in the fast lane are doing so the odds of contact-free pit stops will edge closer to 100 percent.

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IndyCar tech download: Taming the track

Michael Levitt/Motorsport Images Why do black lines lead to a terminal point and the other line leads to winning the race?
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emailBy Stan Sandoval | April 11, 2023 4:11 PM ET

The IndyCar calendar offers what is probably the most diverse collection of tracks of any racing series in the world. This is usually taken to mean that over a season, IndyCar pays visits to the likes of speedways, short ovals, road courses, and street courses. However, the variability in surface type, bumpiness, grip level, and ambient conditions that IndyCar teams will experience over the course of a season is also extraordinarily diverse, and something that engineers are constantly analyzing and assessing as they fine-tune setups in search of every ounce of performance.

Unlike every other sport, in racing each team is not only battling with one another but also with the field of play itself, and that arena changes from week to week (and even session to session) in ways that no other sport would allow. While the likes of soccer, football, and baseball have standardized their playing surfaces – and even gone so far as to play indoors under stadium roofs to protect from outside conditions – teams in racing are left to adapt on the fly to the ever-changing characteristics of the race track.

Engineers are almost always thought of as engineering the car, but there times when a better way to think about it might be that they are trying to reverse-engineer the track, and simply apply the appropriate changes to the car as a result.

Teams and engineers are constantly adjusting a whole host of setup parameters in reaction and anticipation to track surface and ambient conditions changes that occur throughout a race weekend. Being able to adapt (and even predict) these changes offers a huge competitive advantage to those that can continuously keep the car’s setup in the optimum window, even as the variables are changing all around them.

The track surface

The joke that is made wherever race car engineering is taught is that the four most important parts of a race car are the tire, the tire, the tire, and the tire. It’s a saying based on truth: the importance of the tires is no joke, they are the only part of the race car that actually comes into contact with the road. By extension, the most important part of the race track is the surface, for largely the same reason. The state of the racing surface is the dominant factor in the amount of available grip for the tires in a given session, lap, or even corner.

Track temperature is the single biggest consideration when assessing the surface. Tires have an operating window where they produce the most grip: too cold and the rubber doesn’t get sticky, too hot and the tire will oversaturate and begin to slide. Given the relationship between a tire’s pressure and temperature, engineers are constantly adjusting the starting tire pressures based on track temperature in order to keep the tire in its operating window.

Track temperature is hugely influential on tire pressure and temperature, and therefore its effect on overall grip is very powerful. The track grip, usually quantified as a friction coefficient, then dictates practically every aspect of a setup: from downforce level to spring stiffnesses to static alignments to gearing. Put simply, a car setup exists to take advantage of the available track grip at all times if possible, or make the best compromise for overall lap time if not.

Not only does track temperature dictate the grip level, but also the car balance. Since the front and rear tires are different widths, have different forces acting on them, and are used in different ways, a change in track temperature does not have an equal effect on the front tires as the rears. A sudden shift in track temperature will not only change the grip level, but also the understeer or oversteer characteristics of the car. As track temperature itself is constantly changing, an engineer’s job of dialing in a setup is a never-ending task.
Street courses often serve up different surfaces on different parts of the lap, forcing engineers to hunt for a compromise. Phillip Abbott/Motorsport Images

The road material is another factor influencing grip, because that is what has to interact with rubber of the tire. Different types and ages of asphalts, tarmacs, concretes, and sometimes resins are seen over the course of an IndyCar season, and each offers slightly differing amounts of grip. This isn’t so much an issue when the track is one uniform surface, but tracks like Toronto famously use different materials in different corners. In this case, engineers simply have to make more compromises: a setup change that might benefit one corner but hurt another.

Road material is also a big reason why teams go test at tracks after they’ve been repaved. Barber Motorsports Park was completely repaved in late 2019, and because of this there was an enormous increase in grip. Testing in early 2021 was important: laps were more than 2.0s faster than the pole time from 2019 (and that’s despite the addition of the aeroscreen). Such a big difference required not only a rethink on setup, but a completely new stack on gears given the difference in cornering speeds.

Track surfaces can also vary wildly in terms of bumpiness. A lap around Detroit is a very different experience compared to a lap around Barber in this regard. The primary effect of bumps on setup is the spring and damper package. Stiffer cars can be run lower to the ground, which is good for downforce, and are more reactive and better at changing direction. However, stiff cars do not handle bumps well at all. The ability of a softer setup to absorb the bumps and keep the tires on the ground is critical; the tire can’t do anything if it’s not on the track because it’s bouncing up in the air!

Finally, when analyzing the track surface, another vital factor is ‘track evolution,’ or the amount of rubber that’s been put down. To start a race weekend (or after a rain shower), the track is referred to as “green,” meaning a fresh track. As cars beginning completing laps, they will leave a layer of rubber down on the track. The more laps that are run, the more rubber there is on the surface. This beneficial for grip: the best thing that rubber can stick to is more rubber, so the more laps that are run on a track, the faster it gets. This why it’s called ‘track evolution’, and it’s the reason teams typically wait before they start running at the beginning of the first practice, and why teams will always try to leave their qualifying laps as late as possible. Like many of the other factors discussed already, as track grip changes so does the balance, and so engineers will have to compensate accordingly with the setup.

Teams will always try to stay ahead of track evolution because it is relatively predictable. However, a quirk of putting rubber down is that the calculation changes depending on what kind of rubber was put down most recently. Different tire compounds don’t always agree with one another. Engineers will always take note of what series ran on track immediately before a session, as a race weekend typically has many series competing one after another. If for example, a NASCAR session ran immediately before an IndyCar session, engineers would expect the grip to be slightly reduced to start the session, because NASCAR rubber doesn’t aid track evolution for an IndyCar.

Another aspect of track evolution is marbles. If you’ve ever taken an eraser to a piece of paper and seen bits of rubber chunks fall off, then you’ll be familiar with the concept. As tires are grated against the track surface, the worn rubber is shed from the tire and lands off the racing line. Driving on the marbles is a massive grip loss and can be very treacherous; they get between the tire and track surface, like a cartoon character trying to run on ball bearings.

Ambient conditions

As IndyCar races everywhere from Florida to Oregon over a seven-month period, naturally a wide range of temperatures, air conditions, and wind will be encountered during the year. Changes in these conditions will have knock-on effects to the car’s setup that are vital to get right: a team’s ability to adjust their setups as conditions changes can be the difference between having a competitive setup or a poor balance by the time the race comes around.

Changes in air temperature will affect several aspects of car setup. The importance of track temperature has already been discussed, but track temperature is heavily influenced by air temperature and cloud cover. The radiator covers, sometimes called blockers or blanking, come in various sizes and are largely dictated by air temperature. These covers can be seen at the inlet of the side pod, and their shapes differ depending on the engine manufacturer. Covering more of the radiator is beneficial for drag, but also leads to higher oil and water temperatures for the engine, which affects power output. Finding the right compromise of drag, power, and reliability by adjusting these blockers depending on the air temperature can have a huge impact on performance, especially at aero-sensitive tracks like Indianapolis Motor Speedway, where drag and power are the dominant factors on lap time.

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part 2 taming the trackHitting on the right configuration for the radiator blockers can make a massive difference at aero-sensitive tracks like IMS. Michael Levitt/Motorsport Images

Air density, which is influenced not only by air temperature but by humidity and air pressure, has a big effect on a car’s downforce, which in turn influences the starting ride heights. As an example, the same car going the same speed will generate more downforce in denser air. When conditions are predicted to generate more downforce, engineers will need to raise the starting ride heights of the car in order to compensate (and similarly they can lower the car when air density is predicted to go down).

This is done to keep the car operating at a similar proximity to the ground (where generating downforce is most efficient), no matter the air conditions. A car that is not lowered sufficiently in response to a drop in air density will be too high throughout the lap, losing large amounts of downforce due to operating far from the aerodynamic optimum. A car that is not raised in response to an increase is air density will be lower everywhere on track, which can potentially make the car undrivable. A car that is too low will actually be pushed into the ground by the downforce, called ‘touching’ or ‘bottoming’, when the car is traveling near top speed. Small amounts of bottoming are to be expected as the cars approach top speed, but too much will cause the car to hit the ground so hard that it unloads the tires, which can unsettle the car and cause time loss or even force the driver off the track.

Wind is another aspect that can vary drastically, and since it has a huge aerodynamic effect, it needs to be accounted for in the setup. Anticipating the wind is one of the most difficult aspects of adjusting the setup to get right. Drivers and engineers are constantly kept updated on the current state of the wind speed and direction when working trackside.

Typically, drivers and engineers talk in terms headwind, tailwind, and crosswind relative to various locations on the track. For example, when driving on a straight leading into a high-speed corner, a headwind will do several things: it lowers the car’s top speed, it creates more downforce, and also shifts the aero balance of the car. A tailwind does the opposite of these.

As a consequence, the gear ratios are typically adjusted based on the simulation’s prediction for top speed, which will have to accurately account for the wind. From a performance perspective, selecting gears is a give and take between top speed and acceleration. If a big headwind is predicted then the top gears can be shortened to give better acceleration (since the previous top speed is no longer attainable due to the headwind). In the case of a tailwind, the gears will need to be made longer to gives additional headroom to avoid hitting the rev limiter.

A headwind will also lead to more downforce as there is more air going over the wings, so a ride height compensation will be required to avoid bottoming too hard at the end of the straight. A strong tailwind will have the opposite effect: air going over the wings collides with wind going the opposite direction, and less downforce is generated. The result is a grip reduction, and when a tailwind picks up suddenly it can really catch a driver out. A great example of this was in Turn 2 at last year’s Indy 500. Turn 2 is unique at Indy because it’s the only corner without a massive grandstand to shield the track from the wind. Sudden gusts on corner exit caught more than a few drivers out that day.

Finally, strong winds will change the car’s aero balance, or center of pressure. Aero balance is the distribution of downforce front to rear, so it plays a big part in the whether a car will understeer or oversteer, particularly in highspeed corners. The most common method to adjust aero balance is with the front wing flap. However, since this can only be done between outings or during pit stops, compromises in some corners will have to be made for the benefit of others. When dealing with a big headwind, downforce is added, but it will not do so proportionately front to rear – the wind will change the balance of the car. This can be particularly unnerving because a sudden aero balance shift from a gust of wind (especially when a disproportionate amount of front grip is added compared to rear grip), can cause entry instability and lead to sudden spins because the rear can’t keep up with the front.

Further complicating this matter is that fact that all the corners are oriented differently, so a headwind entering one corner may also be a tailwind or a crosswind for another. To protect from this, engineers sometimes choose to lower the front wing flap angle to give the rear a higher percentage of the overall grip if they think strong winds will make the car unstable. That may compromise the balance in other corners, but it will do so in a stabilizing (read: not crashing) manner.

Summing up

The car is constantly interacting with the track, which means the state of the surface and the ambient conditions will play a huge part in how the car behaves. So powerful is this effect that sometimes teams won’t even venture out if they think the conditions for a practice session aren’t going to be representative to the forecast for qualifying or the race. This is also why the morning warm-up is such an important session for teams, as it is the session where the track surface and ambient conditions are typically most similar to the race. Still, from time to time a race will take place in conditions that haven’t been seen at any point in the weekend, and the teams will simply have to react.

It cannot be overstated how crucial a role simulation plays in reacting accordingly to an ever-changing track. It is pivotal for a team to roll off the truck fast, keep up with a changing track from session to session, and determine the right adjustments (or right amount of adjustment) in order to be successful. Many teams have dedicated Simulation Engineers whose job is to match a mathematical model to reality at the end of a session based on the collected data, then use that model predictively for the subsequent session to determine a best course of action.

Even before the debrief for a session finishes, teams are already looking ahead to potential changes for the next session, especially when the turnaround time is tight during a race weekend. Determining the best setup changes to make between sessions is one of the hardest aspects of a race weekend for the engineers; there are an endless number of changes and combinations of changes that could be done. Ultimately, since the track surface and ambient conditions are the same for everybody during the race, the car setup doesn’t actually need to be perfect, or even good. It just needs to be better than everyone else’s.

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How to LeMons - Racing Do's and Don'ts - "Lemonade" - A 24hrs of LeMons Film | Everyday Driver

EverydayDriver
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178,385 views Mar 26, 2020
If you've ever wanted to be a racing driver, we show just how low the bar can be! This compilation of our 24 hours of LeMons experience shows the do's, don'ts, and bad decisions available to everyone. Taken from 3 episodes of our TV show, this has already inspired many novice drivers to start their own LeMons team. We encourage you to try this madness as well! All our TV shows with full car comparison episodes can be found on Amazon and Vimeo, and films on all formats available here: https://www.everydaydriver.com Our Podcast, "The Car Debate", can be found every Tuesday and Friday wherever you get Podcasts. Articles on Mondays and Wednesdays New videos on YouTube on Thursdays. (and sometimes Tuesday too!)

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How good is your simulator?
How racers are simulating their way to success

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emailBy Dominik Wilde | August 12, 2023 11:55 AM ET

As costs continue to rise and prying eyes aim to peek at any advantage they can see a rival working on, simulation is becoming an increasingly vital tool in motorsport. Its advantages for drivers — giving them near endless seat time ahead of events to learn tracks, cars, and procedures – are obvious, but simulation has a much wider use aside from letting people log laps.

NASCAR’s Next Gen car, now in its second season, was of course the product of countless real-world laps at a number of tracks, both on and off the Cup Series schedule. But while it was turning laps on track in late 2019 and early 2020, Landon Cassill was turning laps in the virtual world. Simulation has been a key component of NASCAR for over a decade now, with Cassill describing it as “absolutely fundamental.”

“The simulators are running all day, every day,” he tells RACER. “The only teams that aren’t using simulators at a large scale are the teams that aren’t factory backed or manufacturer supported. The largest teams like Hendrick, Joe Gibbs Racing, Stewart-Haas, those guys are probably in the simulator every single day. Maybe it’s not every driver every day and every team every day, but there’s probably some sort of team representation in that simulator seemingly every day.”

Such reliance on simulation is far from unique. Virtually — if you’ll pardon the pun — every series does it with track testing either outlawed or deemed too expensive to do on a regular basis.
For Landon Cassill, plugging into a simulator yields valuable seat time as a driver along with the vital data for the teams and manufacturers. Motorsport Images

“There’s been an evolution from on-track testing, which is really the best way to test a car but not necessarily the most efficient or cost-effective way,” says Cassill. “Racing series years ago put limitations around testing in an effort to control the costs that were spent on R&D, but if that money’s there, it’s going to get spent and smart people find a way to work around it, so that’s where simulation was created.

“But even before we were driving driver-in-loop simulators, the teams and manufacturers were building their cars and building their setups in simulation programs,” explains Cassill, who first tested with Chevrolet in the early 2010s. “Essentially (they were) preparing a virtual version of their race car and evaluating the potential data of that car before they ever put those setups underneath the real car. So NASCAR’s been pretty far along for a decade when it comes to engineering and simulation.”

It’s not all about cost-saving and efficiency, though. In series where regulations are tightly policed, simulation gives the opportunity to find sneaky advantages.

“In our sport, our cars are intended to look the same,” Cassill notes, “and so we don’t have the visual control of a wing of change or an underbody change that F1 has, where you can see those changes right in front of you and it’s easy to talk about. The teams have no choice but to talk about them or, or acknowledge them. As proprietary as the technology is, they can’t avoid it.

“In NASCAR — unfortunately for the sport, in my opinion, and for the fans — the teams are able to hide a lot of their technology around this stock body. And for years and years, there’s a lot of ingenuity that doesn’t get talked about because we don’t have to talk about it.”
NASCAR sampled Le Mans virtually before the Hendrick Motorsports Garage 56 Camaro took to the real track. Nikolaz Godet/Motorsport Images

The incognito nature of simulation also came in pretty handy for NASCAR’s recent foray at Le Mans. Before the Garage 56 project even got off the ground, Cassill may have — unknowingly, at the time — laid some of the groundwork while helping develop the Next Gen in its early days, as he divulged on Twitter back in June.

“I got a call from NASCAR — I’ve been in the sport for a long time and know a lot of the guys in the R&D center — and so got a call from them to come do a test, which to me wasn’t too unusual and I was happy to help with the Next Gen,” he explains. “They had a couple things that they were working through that I had known about, just being a full-time Cup driver at the time. I had known that they were testing and solving and developing that car to get it ready for us to race in the Cup Series.

“So nothing was too unusual for me, but they did ask me not to share much of the test plan when they sent it to me and showed me what we were doing — and the fact that we had Le Mans and the Daytona road course on the test plans. They had asked me to be prepared to run laps at Le Mans.”

For Le Mans, a baseline was needed. That was done with the help of iRacing laps in a Mercedes-AMG GT3 racer, and the previous generation of Cup Series car.

“It wasn’t super in-depth — it’s not like we were really turning big knobs, but they wanted to see a baseline of where we are at on this car at Le Mans. I wouldn’t say at the time that I had any specific knowledge or indication to myself that this was a potential Garage 56 entry and from that point on, I didn’t think much of it, to be honest with you.”

In fact, despite what NASCAR’s interest in Le Mans would develop into over the next three years, the simulator laps on Daytona’s road course drew Cassill’s attention more.

“I was, at the time, more interested in the fact that I ran laps on the Daytona road course as well because, being a current NASCAR driver, Le Mans seemed so far out there,” he says. “To me, I was more thinking, ‘Oh man, I’m probably going to end up racing at the Daytona road course’ and I hadn’t heard anybody talk about it. Obviously, that came into fruition pretty quickly because the Cup Series raced at the Daytona road course in short order after that.

“So the Le Mans thing wasn’t even really on my radar in the immediate future, other than I thought it was very exploratory. It didn’t feel random — I did feel like there was a purpose that NASCAR wanted to see some data of that car at Le Mans, how fast did it go down the straightaway and what the lap time looked like, the braking zones and what a general lap data would look like. So I knew there was a purpose. I just didn’t put too much thought into it like, ‘Oh, this thing might actually race.’

The on-track benefits of simulation to prepare cars and drivers might be relatively new, but the reasons for it are apparent. But now we’re also seeing engineers get their start in the virtual world as well.

“I’d say it’s happening a lot,” says Prescott Campell, an Oxford Brookes University student currently working as a structural engineer at the Williams F1 team, but who is also an engineer for Williams’ Esports division. “A lot of the other students I study with work part-time as engineers for various Esports teams, and they develop these skills that you don’t really learn during university — how to set up a race strategy, that’s not really a course that’s taught.

“So they can build these skills by being engineers for Esports teams and the software that’s used to analyze data is the exact same software that’s used in real life, so you get familiar with software that they need to use to get a job after graduating.”

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Williams has found useful synergy between the engineering requirements of real world motorsport and Esports, which can help prepare young engineers for racing. Zak Mauger/Motorsport Images

The idea of an “engineer” in a virtual world might seem baffling at first but, as with driver and car prep, the reasons behind it are straightforward.

“With anything that’s extremely competitive, you need as many tools and people on the case as possible to efficiently find every advantage you can,” says Campbell. “It’s possible, but it requires a lot of work for a driver to converge on setups and they might not have the skills to use the software and the tools available in order to exploit these advantages that they might never come across.

“So it takes an engineer that has experience with data analysis and the tools they need to extract data from the driver running, then sweep through it, working with the driver — who might also pick up things that the engineer might not notice — and then try different things when the driver’s complaining about something or saying the car can be improved in a certain way.

“It’s the engineer’s expertise that can tell them what sort of setup change and direction they can go in. That’s not something the driver might know unless they have so much experience with setup changes.”

The virtual world also gives engineers — either working exclusively in the virtual world, or preparing for the real world — more time and space to figure out solutions.

“In real life, often the engineer has to make informed decisions on what not to look into, and to decide just based on their own experience, different aspects of the car to ignore or keep the same while they try and converge on a precise setting on a different aspect of the car,” Campbell says. “While in sim racing, you can basically sweep through all of these things because you have as much time as the drivers are willing to spend online.”

That being said, for drivers, the idea of “just pressing the reset button” feels like less of a luxury.

“Even just the process of resetting the lap if you make a mistake or crash still takes time — the time it takes to reset, but also the time it takes to start that lap over,” explains Cassill. “If you’re doing that, not even on a warmup, on a run change that you make in the car so that they can compare the data after the fact, you’re trying to get a clean lap for every single change.

“If you keep making mistakes or if you keep crashing, you’re kind of muddying up the data and resetting and that time compounds on itself. Just like any line of work — racing isn’t really that special when you’re trying to think of time over productivity, right? Just like anything, you get to the end of your shift and you’re like, ‘Man, have two more runs to get through — where did we lose that time?’ So I always try to be as efficient as possible in my feedback and how I get up to speed.

“To me it’s very similar to the final hour of a practice session. It’s like a two-minute drill for a quarterback. I try to approach the sim sessions as seriously as I would a practice session and be as efficient and diligent as possible.”

Because saving time, ultimately, is what results on the racetrack are all about unless you race in IMSA which is known for juggling and penalizing so as to screw you out of anything which you gained as the result of hard work during a race. IMSA wants everyone to "be equal" and everyone to get a participation trophy since competition is bad.........according to the IMSA liberals.

The glaring example is IMSA holding the leader in the pits until they are so far behing that someone else wins the race instead of those who did it better.(Daytona 24) Another example is presenting the winners trophy months after a race is completed (24 Hours Lemans) , while liberal IMSA officials decide which IMSA liberal that IMSA thinks should have won.

https://www.tamparacing.com/forums/a...w-you-out.html (6,000 views)

Most people believe that by competing, everything gets better for everyone.
Liberals believe that it is unfair to be better than anyone else and that only liberals are allowed to determine which liberal is allowed to be better.

IMSA liberals believe that endless hours of pit stop practice is unfair to teams who did not practice at all..
.and the teams who had faster pit stops "unfairly stole a win away from it's rightful owners."

Liberals want EQUITY OF RESULTS and NOT EQUALITY OF OPPORTUNITY TO HAVE SUCCESS,
where those who do something better are rewarded for their efforts at achieving more and better results.