Ross Bunnell, Engineer for Dale Coyne Racing
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Program: Engineering an IndyCar for Racing Success Speaker: Ross Bunnell, engineer for Dale Coyne Racing; Colin Zagel, assistant engineer for Pietro Fitipaldi’s 51 car Introduced by: Douglas Sherow Attendance: 79 Scribe: Tom Lauer Editor: Carl Warner This week’s Zoom recording can be viewed at: http://www.scientechclub.org/zoom/634.mp4 This presentation was a virtual tour of the Indianapolis 500 garage area associated with Dale Coyne Racing, 6 days before the 500 race. Our hosts were Ross Bunnell and Colin Zagel, two engineers for DCR Engineering. The hosts provided a walk through the garage and spoke briefly about the preparation needed for both qualifying and race events, including what it takes to get a car qualified and how to get a car to the finish line. This was followed by an extensive question and answer session where Scientech members asked over 40 questions. Their schedule in Indianapolis is most of the month, and their daily work hours are typically 8:00 am to 8:00 pm, except when they work longer, which is often. Indy cars are different than NASCAR cars, for example. Indy cars are open wheel racers, with no fenders. They do have wings and a different aero package providing less drag. Even among Indy car races, oval tracks are different than road courses with respect to the car setup, for example, the amount of downforce employed. With the high 230 mph speeds in Indy, simple things like radio antennas, seams in body, etc. could influence airflow and speed. In Indy this year, the difference in qualifying between the fastest and slowest cars was only about 2 mph. Individual team engineers partnered with either Honda or Chevy for engines. These manufacturers provide engineers to assist the race teams in setting up their engines for maximum performance and the ability to qualify fast, yet, get to the finish line after 500 miles. Some of these things include temperature range thresholds for the engine and gear box. The engine needs to be hot while the gear box should be cold for qualifying. Keeping these things in perspective is what the engineers do for the team. The qualification set up is for qualifying only. If this setup were to be used for the race, the car (engine) would likely fall apart in 30 laps!! During qualifying the tires get worn quickly, something that would not work during the race. We then took a virtual tour through the garage. Dale Coyne Racing is entering two cars this year at Indy, although there were more in the garage. Some were spares and there was an extensive amount of spare parts, including engines, wings, body parts and a lot of stuff that was difficult to understand. The tour began near the “Club Coyne” entertainment area for sponsors, supporters, and other guests. Vol. 102 No. 21 May 24, 2021 Page 2 Cars are designed to come apart quite quickly and in sections. I think we saw an engine in parts that we weren’t supposed to see!!!! This brief tour was followed by a question and answer session using the chat feature in Zoom. Questions: Some of the below “questions” were turned into statements for brevity or clarity, or to eliminate redundancy. In addition, questions/answers were in the order they were presented. Wings on the car are set by the mechanic and can be adjusted in the pit, but there are no aero changes by driver possible. These in race adjustments – front and rear wing angle – allow for changes in downforce. Adjustments are all trade-offs in performance, including adjustments of wings, suspensions, roll- center, etc. Much of these adjustments are based on how the driver wants the car to feel. General overall stiffness in most cars is close, but there are some minor differences. In addition, adjustments are different for qualifying (clean air) vs. racing in traffic (race conditions). The same tires are used by everybody and tires are filled with nitrogen, not just “air”. The steering wheel was shown with all the controls. Although our hosts indicated it was pretty simple, us non-racers may have begged to differ. The steering wheel had shift paddles, quick release controls for exiting the car by the driver, clutch pedals, overtake buttons for extra boost and rpm, radio controls, pit lane speed control, shock controls to adjust weight in car corners, reverse button, reset alarm button, engine control (fuel and ignition) to control engine damage, neutral button, and a large display for what data the driver wants to see, such as shift lights and engine indicators. At least in a couple of cases, a diabetic driver can monitor his/her blood sugar levels and drink water or sugar as needed during the race. Can adjustments be made based on fuel load? Not really, but cold temps of new tires after a fuel (pit stop) will have lower pressure and have the car ride lower, influencing the aerodynamics of the car. What changes are permitted after qualifying? Current rules allow for many changes, including a new gear box and engine. Qualifying setup is different from race setup and some parts may change for the race. How many setup changes can be made? Tire pressure, wing angle, and mostly minor changes. How many set up changes can be made during the race? Only tire pressure and wing angle are significant and these need to be done in the pits. Who makes decision as to tire pressure? That is up to the race engineer. How well can a car be repaired after accidents? Wings can be changed easily. On ovals, repairs tend to be bigger compared to road courses due to speed of impact. Accidents happen – can you repair the car overnight? Yes, but not fun. What is the weight limitation for drivers? Balanced up to 185 pounds driver’s weight. If the driver weighs less, the car needs to add weight, but can do so in a variety of locations. If the driver is over 185, then some consideration is allowed for a weight reduction to 185. What is the educational level of staff? Mechanics usually BS, often in majors like motor sports engineering, or mechanical engineering. Vol. 102 No. 21 May 24, 2021 Page 3 We were then shown a driver’s cockpit with the driver controls in the car identified, on/off, roll controls, etc. sensors, radio, computer gauges, damper pot, Cosworth electronics. How hot does it get in the cockpit? Up to 110 degrees. If a cooling system would be employed, then that would take away from the engine performance. Hence, a cooling system is mandatory for all cars, whether it is desired or not, leveling the playing field and providing cooling for the drivers. What does the team do in the off season? Laughing!! There is no off season, but they do try and get out and have some fun with cars, including go-carts. Do you think we will see Indy cars with electric motors? Maybe, but it would be expensive. How much down force is there in a turn? For qualifying about 2000 lbs., but for a race ready car, about 2300 lbs. Tires can be controlled during the race (tire pressure, etc.) and is one of the few things that can be controlled. Some drivers are better than others feeling/reading tires and have a sense of how to best manage tire pressure, control, and wear. Drivers wear simple and basic ear buds which simply provide a connection to the pit. Sometimes a booster is employed at larger tracks. Everyone uses the same fuel. Favorite track and why? Ross: Road America has really good food. Colin: Indy GP is good, Long Beach and Road America are also favorites. Colin Zagel (L) and Ross Bunnell (R) explaining front-side steering wheel controls .