[HO] iRacing 2.0

The 2018 Season 1 build brings with it another physics overhaul to the asphalt oval series of the iRacing Service. In March, we saw sweeping changes across both the Class A and Class B NASCAR iRacing Series vehicles in an effort to bring the two cars closer to their real world counterparts and the Season 1 build in December will take these changes even further, with many of the changes being adapted to the NASCAR iRacing Class C Trucks as well as the NASCAR National Series car.

One of the first things you'll notice when getting behind the wheel of these cars is a dramatic change in aerodynamic performance. Each of the cars updated in the Season 1 build have had a full rebuild of the aerodynamic map, with each car getting its own unique update:

-Monster Energy NASCAR Cup Cars: The Gen 6 cars used in the NASCAR iRacing Series and NASCAR iRacing Class A Series have had a full aero-map rebuild to bring them up to the 2018 regulations. A reduction in overall downforce and sideforce will place more control in the drivers hands and reduce dependence on aerodynamics relative to previous builds.

-NASCAR Xfinity Cars: An aero-map rebuild of the Xfinity Class B cars brings downforce levels down to the numbers expected from the 2018 specifications, as well as a mild reduction in overall sideforce acting on the car.

-NASCAR Trucks: The Trucks have had the most dramatic aerodynamic change of all four NASCAR vehicles. In previous builds the Truck has had too much rear downforce which has required chassis setups to be mechanically very loose. This has caused rear tires to overheat on large tracks where aerodynamics are key, usually resulting in a spin. For the 2018 Season 1 build, the Truck has had an increase in front downforce to correct this issue. Not only has this corrected the issue with overheated tires, but testers have said this makes the Trucks drive even better than before!

-NASCAR National Series Car: Similar to the Trucks, the National car sees a slight increase in front downforce to correct aerodynamically-induced understeer issues seen in previous builds.

The updates were not limited to just aerodynamics! In fact, a lot of changes were made to the chassis themselves to bring them up to spec with what you see on TV on any given Sunday. While the aerodynamic updates were tailored to the specific car, these chassis updates were made across the board:

-Front Suspension Geometry: The front suspension geometry and kinematics were updated to improve platform / roll / ride height control. Drivers will see issues that were common at short tracks like mid-corner balance shifts, late corner spins, and the high splitter heights have now been erased completely.

-Sway Bar Update: The code for the front sway bar has been updated to more accurately produce the roll stiffness values that the various sway bar arrangements should produce. Further, sway bar preload limits have been narrowed even further to bring them in line with NASCAR's inspection process.

-Front Shock Rebound: For the Trucks and Xfinity cars, maximum rebound in the front shocks has been increased significantly. The Cup cars have had a mild increase in rebound. Setup builders will notice that a full-rebound shock can now be used to "tie down" the front end. This update has also opened up the possibility for various setup types without sacrificing speed.

-Track Bar Rake: When the car is loaded into the world and the car settles, the track bar heights we set in the garage are not the values registered in the sim. With the 4" rake limit imposed in the March 2017 build, this produced an effect where the right side of the track bar could never be higher than the left side. To correct this, the range has been opened up to allow for proper track bar configurations. No need to worry though, as the issue with high rake angle and rear toe has been eliminated with a tech inspection check on the rear toe values.

Finally, we move to the most dramatic change drivers will feel in the cars: Tires. Great care was taken when updating the tires to not only slow the cars down, but put a much stronger emphasis on tire management. All told, cars should be 1-3 seconds slower at 1.5-mile tracks, as well as seeing a much steeper initial falloff for over-stressing tires. Lap times, in general, should be right around what we see in the real world, and how you break-in a set of tires will determine how long they last through a run. Drivers will need to learn to brake properly for a given track as well as break the old habit of getting to the throttle too early. Should you go all out for the first five laps and try to get away from the pack or should you work the tires up slowly? The choice is up to you, and that decision could very well be what wins you a race (or loses it).

In addition to these major changes, minor alterations to the physics have brought the cars closer to their real world counterparts than ever before. For each change made to the cars, none were accepted unless they produced the correct values. Downforce levels, tire loads, lateral forces, and even details such as how long drivers have to wait on the throttle were meticulously changed until the requirements to drive these cars at their limit matched what the real drivers have to do to drive their cars at the limit. Testers have all agreed that this is the most fun these cars have ever been to race, and the data shows that they're the most realistic they've ever been on track. We're thrilled to finally get these updates out to the public, and look forward to racing with you in the 2018 NASCAR iRacing Season.

Yet another exciting development cycle for Dirt Oval on iRacing! We wanted to give our dirt racers a quick rundown of what is headed your way when the S1 build drops on Tuesday:

General

•We learned a great deal about our dirt surface model throughout the GRC dev that helped us better understand how to reduce forward traction on the dirt surface, bringing the need for additional throttle control into the picture. This update was applied to all dirt oval tracks and has resulted in a nice improvement to the feel and grip level of the dirt surface as a whole for all the cars.
•The variance on Official Series starting track usage has been opened up, so there will be more variation in the starting state of the track from race-to-race.
•The default value for the starting track state in Test, Practice, and Unattached Qualify sessions has been increased to make these tracks closer match the starting race conditions. The variance for these values has also been widened slightly. This should help everyone keep their test sessions productive.
•Heat racing for a select few of our Official Dirt Oval Series!

Tracks

•Knoxville! What else needs to be said? The art team did a marvelous job, and we think you will be blown away by the look and feel of the racetrack.
•We have hosted some very long sessions here in the 410 winged sprint cars and the track progression is outstanding. By the time you hit 2000laps, the line is right up on the fence or hooking the berm with sliders and cross-overs flying all over the racetrack.
•With hosted heat racing coming online in the very near future, who will be the first to host their own Sprint or Late Model Knoxville Nationals?!?! Should be pretty epic.

Dirt Midget

•The much anticipated midget has finally arrived! These cars are light and nimble with plenty of bottom end turning a lot of RPM! Lively little cars to say the least.
•We were fortunate to have the best real life dirt midget racers in the world join us throughout the entire development process, and their dedication to the project really shines through in the finished product.
•These cars are a bit more forgiving than the non-winged sprint cars, yet still require a great deal of control and finesse from the driver. They wheelie, they three wheel, and they throw amazing sliders—we think they are an absolute blast to race and we think you will agree!

Dirt Non-Winged Sprint

•In development of the midget, we made some great strides in understanding how to tune our suspension model to allow the car to pitch and roll more realistically, which really worked wonders when carried over to the non-wing sprint cars. You’ll find in this update that the cars are a bit more forgiving and really tend to drive off the RR tire much more realistically than they have in the past. The car feels softer and more alive for sure, making for a nice logical step up in weight, power, and size from the midget.
•Starting track state for the non-winged sprint Official Series, most notably the 360, has been dialed back a bit based on member feedback. The tracks should be more tacky this season for that series.

Dirt Winged Sprint

•The same suspension updates that were developed on the midget and carried over to the non-wing cars were carried over to these guys as well. You’ll notice that the car is a bit more lively over bumps and ruts and tends to sit back on the RR a bit more if you get out of shape or slow down too much on corner exit. You’ll be needing to work a little harder to keep the car winged left center-exit, which we felt was a nice improvement in realism.
•The aero sensitivity to top wing angle and location have been adjusted slightly to promote a more realistic down force vs. drag tradeoff, meaning the wing angle and location will require a little more thought and tuning to get right from track-to-track.
•You’ll find this car is now more laterally stable in the slick but requires more throttle control to maintain forward traction.

Anyhow, that's about everything I can think of for now. Really looking forward to everyone getting to give things a go next week!