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Mayer’s Notebook: Petit Le Mans

Risi Competizione engineer Rick Mayer previews this weekend’s Motul Petit LeMans…

Photo: Risi Competizione

Risi Competizione race engineer Rick Mayer previews this weekend’s Motul Petit Le Mans, where the Houston-based team returns to action for the first IMSA WeatherTech SportsCar Championship race since the Mobil 1 Twelve Hours of Sebring in March.

The Track: Road Atlanta is one of the favorite tracks for Risi Competizione and most of our drivers. Favorites tend to be the ones you’ve had success at, and this is no exception.

It’s a fast track layout with a variety of different types of corners, technically challenging for both the drivers and engineers. It’s a busy track for the drivers. The track requires a lot of concentration and continuous driver inputs of throttle, and steering. You have to hustle the car here to go quickly.

The requirements to go fast at Road Atlanta are always the same: You need a good platform for the high-speed corners – Turn 1, the Esses and Turn 12; You can gain a significant amount of time using the apex curbs effectively at Turn 3 and the exit curbs of Turn 5; The curbs at both Turns 7 and 10 also yield lap time.

However, as much as you need the curbs for a quick lap time, you have to exercise caution as using them repeatedly here ‘could’ lead to failed drivetrain components. It’s a long 10-hour race and you need to be somewhat kind to the car; you have to finish to win.

Top speed is very important as there are few places to pass.

Setup: Stiffer (springs and anti-roll bars) is better for platform support, but curbing is so important here, it’s a compromise. A stiff setup also makes cleaning the pick-up off the tires easier as you can load the tires harder.

With such a big field (and short track), the number of times that a GT car may have to go off the racing line, and therefore experience pick-up, will be increased.  Numerous safety car periods are common at Petit making clean hot tires for restarts an important consideration in tire compound choice and setup. Dampers that give support, but blow-off on the curbs, can make a big difference here, not just in lap time but longevity of the drivetrain components. 

Top speed and downforce level will be based on peer group straight speeds. Greater overall downforce is the quicker way around the track and better for tire life, but you can’t let the competition drive around you on the straight.

Passing will be difficult, especially in GTLM with the nine super-competitive cars from five different manufacturers. The best passing spot will be braking into Turn 10. However, if you can’t keep up on the straight you won’t be in a position to out-brake someone into Turn 10.

The track isn’t particularly hard on brakes, but you need the brakes to last the 390+ laps that the GTLM cars will run during the race.

Keeping the car low to the ground (low running ride heights) is a challenge at Road Atlanta. Your options are to run very high ride heights (Sebring track levels) or stiff springs or bump rubbers and packers to hold the car up in the large compression areas.

The main areas where the car will contact the track are the bumps in the middle of Turn 1 (left rear) and the curb in Turn 3 (right side), either the curb itself or the landing from launching off the curb. Your ability to setup around these features will ultimately determine how low to the track you can run the car. 

The Race: Traffic will play a large role as always at Petit particularly with the large car count. Keeping out of trouble will be crucial for success.

With a 10-hour race, pit strategy is easier as you’re not forecasting the leaders lap count or time to finish as in previous years when it was a distance based race.

Pit work needs to be only fuel, tires and driver changes with the occasional addition of engine oil. Anything extra or slow pit work will put you at the back of the field quickly. It’s so hard to pass same class cars, you can’t lose positions in the pits.

Qualifying is less important at these long races then our usual 2 hour and 40 minute events, but keeping up in the lead pack will always be vital due to the level of competition and how difficult it is to pass at Road Atlanta. The current caution rules should keep the GTLM front-runners on the same lap.

Risi run Ferrari’s have fared well at Petit over the years; it’s one of the team’s more successful venues. Let’s hope history repeats and we can end the season on a high note.

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4 Comments

4 Comments

  1. jason

    October 10, 2018 at 9:36 am

    “The current caution rules should keep the GTLM front-runners on the same lap.”

    Mr. Mayer I think is implying that he expects a high number of safety car periods during the race

  2. Old Trombone

    October 10, 2018 at 3:28 pm

    Brilliant Engineering writing! Thanks very very much for these amazing insights that fans so rarely get to read. Cheers!

  3. JeffB

    October 10, 2018 at 9:41 pm

    Very interesting read. Thanks.

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