Performance and Setup

A work in process. Please check back Regularly.

The following data is all from Road America running the Shell 99 Lola.

I have added this section to provide some understanding of a modern ChampCar's potential in the hands of an amateur. I became hooked on the idea of an Indy or ChampCar while watching Duncan Dayton come down the hill at Road Atlanta, shoot down the front straight then fire back up the hill at what seemed to be video game speeds. A 1600 pound car with over 800 bhp will accelerate well but it is the phenomenal level of cornering and braking grip that sets these cars apart from anything short of a modern F1 car. My Chevy Spice will come close to accelerating with my Lolas but it is utterly tame in a driving comparison.

All this corning and braking force comes from grip generated by the aerodynamic downforce of a modern Indy or ChampCar. Lola provides a tremendous amount of wind tunnel data for different downforce setups. Of particular value are the tuning maps that detail the changes in total downforce, drag and balance with changing front and rear ride height. You quickly garner and appreciation for the car's need to be run on the deck. The Longbeach downforce summary gives you an appreciation for the amount of downforce a 99 Lola can generate. The 4822 pounds of downforce at 200 mph equates to (corrected from previous printing) roughly 2000 pounds at 130 mph or the weight of the car and driver plus two hundred pounds! There are a lot of 130 mph corners in the US when you carry that much downforce. The net result can be seen on a plot of lateral g forces. This plot was from a qualifying lap in July of 2004 and shows over 4G of lateral acceleration at 170 mph going through the kink following the carousel. I estimate the downforce through the kink is somewhere around 2800 pounds. It took me three years to develop the setup and trust the car enough to almost go flat though the kink. It is interesting to note that the 10% lift combined with the turning force causes a .5G spike of longitudinal deceleration and a corresponding flat portion on the speed curve.

Using the Motec software to compare the 03 and 04 qualifying laps shows the dramatically improved confidence in the car through fast sweepers. This comparison also shows that a half second was lost by being balked in turn three in 04 versus the clean run through this corner in 03. The 10 mph reduction through turn three meant less speed all the way to turn five and a 5 mph reduction in top speed on this straight. Being able to do back to back comparisons for different sections of the track has proven to be an invaluable learning tool for both my driving and setup skills.

The first difficulty I had in driving an aero car was coming to grips with the "aero lull" concept. Pros do not know anything about this but amateurs do. My first instinct with any car is to slowly carry more speed through a particular corner until I can feel the car loosening up. If I am lucky and I have done my homework, this loosening comes in the form of reduced steering effort as the car approaches understeer. If I have not setup the car properly, I get a sick feeling in my stomach as the back end starts to loosen up. If you use the "little bit faster" approach with an aero car, you will hit a point on certain corners where the car starts to feel bad and your normal reaction is to say that is fast enough. Yet, if you add a few more mile an hour, the car gains more aero grip and starts to feel progressively better. Turn one at Road Atlanta is a good example of this. Apex at 115 mph in a ChampCar and things feel a bit weird. Add twenty miles an hour to that and the car is absolutely plastered to the ground. Once you know this and have a better feeling for the car, you will find that you jump on it right out of the pits and never go slow enough to feel the lull (being mindful of cold tires, of course).

The second difficulty came with braking. A modern ChampCar will develop over 3Gs of initial braking force. The sequence goes something like this. At the end of the straight at 190 mph you stand on the brake pedal as hard as you possibly can at which point you are thrown hard up against your belts. You literally can not lock the wheels at top speed. Almost immediately, you have to come off the pedal because you have bled off so much speed that you have lost tremendous downforce and thus ability to brake. Rolling off the brakes and having a third the braking power at the end of the braking zone makes you think that you broke way too early. It is a similar sensation to coming off the interstate where you were doing 80 mph and thinking you are crawling at 40 mph. The next time, you brake later and now find that there is not enough brake zone to let off the brakes sufficiently and you lock up and fly off the road. It is just one of those things that you have to accept. I make it easier by waiting until late in the brake zone to do my downshifting. You can see this on the track map with gears displayed where all the changing is done in the last half of the braking zone.

Road America in 04 marked the need for ride height control and damper tuning. 05 will be spent testing softer springs with third spring chassis support along with targeted damper adjustments. I cover the first in Getting On Track and the second in Suspension. In addition, I will be looking at adding ride height, shock travel and wheel load sensors to the data acquisition system.

This is a comparison of a qualifying lap at Road America in 03 versus 04, both in the Shell 99 Lola.

This is the 2004 qualifying lap at Road America in the Shell 99 Lola.

This is the Track Map representation of the 04 Road America qualifying lap in the Shell 99 Lola.

Here is an example of the overall downforce summary and ride height versus downforce data for the 99 Lola. This is the type and nature of the wind tunnel setup data provided by Lola.