Sonoma Raceway Engineering Guide

Scott Dixon rolls through the Turn 9 Chicane during the GoPro Grand Prix of Sonoma at Sonoma Raceway — Photo Credit: John Cote

IndyCar heads to Sonoma for the season finale this weekend with six drivers still eligible for the championship. Let’s take a look at the Engineering Guide for Sonoma Raceway in California.

Surface: Road Course
Distance: 2.385 miles
Laps: 85

Sonoma is IndyCar’s tenth road/street course of the season, and also one of the toughest. The track features very short straights (one is made out of the drag strip located at the circuit), an esses section, and a brake heavy hairpin that leads on to a curvy front stretch. Besides navigating a rolling start with other cars around them on a narrow front straight, drivers also need to be ready for the heavy braking section heading into turn 2. The steep turn coupled with the braking can upset the balance of the car and send drivers running wide in qualifying and at the start of the race. 


The things teams will need to focus on this weekend are downforce through the high speed corners and acceleration rather than top speed. Cars don’t really get a good chance to top out going around this track, but getting up to speed on the slightly longer straights is imperative. Through the esses, maintaining momentum can really help you close up on a car that is struggling through the section. The hairpin like corners of 4 and 6 will provide some good overtaking opportunities in addition to the “classic” hairpin that is turn 11. A poor run out of the final turn will make you a sitting duck to cars behind on the front straight.



Sonoma is unlike almost any of the other road courses this series competes on. It doesn’t have a trademark long straight like we see in Long Beach or St. Petersburg. Therefore, it’s going to require a setup unlike any of the other tracks. Chevy have won six of the nine road/street course races this year, and they seem to have the upper hand heading into Sonoma as well. Their aero kit has been the winner most of the season despite Honda’s recent push in winning two of the last five road course races. 

However, some of the reasons for Honda’s slower pace could be because of higher downforce levels on the stock aero kit setup. Their front wing element has always had downforce in mind, with three flap elements and two endplates holding two more flaps. This has slowed them down on the straights but will benefit them in the turns. Also, if you look at their rear pod (pictured in red below), you can see the curved bottom edge that serves as a diffuser for the car. It sucks the air out from beneath the car, lowering the air pressure and therefore increasing downforce without adding any additional drag. 



Chevy opted for an angle parallel (no curve up) to the ground which makes their diffuser less effective. I don’t know if it will allow them to outrace the Chevy’s and win, but it could certainly help make them more competitive on a track where mid to high speed corners are plenty.


Update: 8/29 – If you have any more questions about the cars or Sonoma Raceway (or IndyCar engineering in general), let me know in the comments below and I’ll do my best to answer!

Why Marco Andretti Lost Detroit Race #1

Marco Andretti exits Turn 7 during Race 2 of the Chevrolet Dual in Detroit at Belle Isle Park — Photo: Chris Owens

The first race for the doubleheader in Detroit was a strategy showdown as rain plagued the early parts of the race and threatened again in the closing laps.

Carlos Munoz secured his first win in the Verizon IndyCar series and led eight laps on Saturday. His teammate, Marco Andretti, came in second place – but that wouldn’t have been true if Munoz hadn’t have been able to stay out two extra laps after Andretti pitted. 

Andretti came in on lap 40 leading the race by around a second, and he had a 20+ second gap to the main field. On his black tires he was lapping two to five seconds a lap quicker than the main field who had switched onto rain tires eight laps earlier.

Munoz had followed suit with Andretti, partly because they are teammates, and ran the same strategy. When Andretti came in to pit (his fuel was low or else he would have stayed out longer, to gain a bigger lead), Munoz made the move to follow, but was blocked from the pits by a slow lapped car. He was forced to do another lap on his black tires, but it turned out to be the best thing that could have happened to Munoz. 

In just those extra two laps, Munoz gained an astonishing 23 second lead on Andretti. His black tires were lapping 10 seconds quicker than Andretti’s new wet tires. 

If Andretti had been able to stay out as long as Munoz did (even though Munoz’s longer stint was party due to luck), he would have surely won the race. He had the lead, and barring any pit-stop problems, he would have rejoined in front of Munoz – and the rest of the field.

Andretti himself made a great call in staying out on the slick tires when the rest of the field was pitting for wets.  But his early pit-stop on lap 9 meant that he didn’t have the fuel to stay out as long as he would have liked during the second stint.

And win the race. 


Data provided by Firestone Timing

Nasr looking forward to scoring points again in China

Felipe Nasr on track during the Malaysian Grand Prix on March 29, 2015. — Photo: Sauber

Sauber driver Felipe Nasr is looking forward to scoring points again in China after a disappointing Malaysian Grand Prix that resulted in a 12th place finish for the Brazilian. Nasr took advantage of the small field in the opening round of the 2015 season and secured a fifth place finish in Australia.

Shanghai proves to be a tough race each year on tires and cars, but Nasr is confident his team will get it right in China. Lewis Hamilton and Mercedes got it very right last year and won the race by a whole 18 seconds. 


“The track has a combination of high-speed and low-speed corners, which is quite demanding for the tyres and challenging to find a good balance for the car,” Nasr said. “Besides that, the circuit has a straight which is the longest on the whole race calendar.”


Nasr added that the straight “could be positive for us as we have a strong top speed. As the track has some low-speed corners, traction can be important as well.”

“I am looking forward to a positive race weekend and to scoring points again.”

The Chinese Grand Prix will take place on April 12th, 2 a.m. EDT.