F1: We Don't Need No Stinkin' Displacement

Last year, F1 commentators were busy lamenting new rule changes that outlawed the 3.0-liter V10 powerplant. After Renault introduced the motor to the sport in 1989 (with Williams), the configuration quickly became the sport’s defacto standard. Then, in the name of safety, the FIA mandated a reduction in engine capacity from 3.0 to 2.4 liters, and reconfiguration to a V8. Pundits saw the move as one more step toward the spec series they all so desperately want to avoid. Ladies and gentlemen, the jury is in.

The new rules, designed to decrease racing speeds, also eliminated attendant cutting-edge technology, such as variable-length intake trumpets (key to the tuning and tractability of the high-power V10 engines). All in all, the FIA’s new engine rules reduced engine power by around 20%, corresponding to the 20% drop in displacement and cylinder count. In real world terms, the move reduced engine power by around 185 horsepower.

During the off-season, the FIA was lambasted for the switch. Some journalists and drivers (no need to name names, Jenson Button) claimed a schoolgirl could drive the new formula cars, that the element of overwhelming power had been removed from the equation. Perhaps they had a point. The drop from 950 to around 775hp was drastic.

But the pundits failed to foresee the resulting acceleration of aerodynamic and tire technology. As this season’s results prove, the two technologies helped compensate for the rule change. Within months, the smaller-engined cars’ 2006 lap times leaped straight back to their 3.0-liter levels. Here’s the deal…

When tweaking a race car’s aerodynamics, designers must make a basic tradeoff: downforce vs. drag. While adding wings to a car can increase downforce, the gain comes at the expense of drag. Drag increases a vehicle’s high-speed grip, but reduces its top speed. Wing angle, wing size and configuration all play vital roles balancing the two forces.

This is clearly evident when comparing the rear wing angles used by the F1 teams at Monza and Monaco. Looking down the length of the car (from nose to tail) you can easily see the changing cord, or vertical dimension, of the rear main-plane: steep at Monaco, shallow at Monza.

A current F1 car’s front and rear wings only generate 30 to 40% of the total downforce. Underbody airflow management and the diffuser account for the rest; it’s absolutely crucial to the car’s handling at any given speed, as well as the car’s maximum velocity. Correctly manipulating the airflow around the rear of the car is especially important to the performance of the underbody aerodynamics.

The reduced dimension of the new 2.4-liter V8 liberated significant room for development in this mission critical area, placing even more emphasis on the packaging of bodywork and components in the car’s rear. Designers greatly enhanced the efficiency of the undertray and diffuser– to the point where they are largely responsible for the similar speed and grip levels achieved pre and post engine rule change.

The reintroduction of tire changes during pit stops was the other major change for the ’06 season– which also ended-up subverting FIA's intention to lower racing speeds. The maximum stint length during a typical race strategy is now around 25 laps, depending on track conditions. Because one set of tires no longer has to survive an entire race, F1 tires have changed dramatically, both in compound and construction. Equally important, last year’s championship saw Bridgestone struggle unsuccessfully to meet the grip and wear benchmarks set by Michelin. This year, the gap has closed between the two manufacturers’ tire performance.

As two and three stop strategies are the norm for the front running teams, they can run aggressively soft tire compounds which greatly enhance their car’s dynamics. The intense battle between the two tire manufacturers has also led to extreme speciation in tire compounds and constructions. Each tire choice now has a very narrow operating window, particularly with regard to temperature. These ultra-specialized compounds, while extremely quick inside their respective windows, have shown themselves to be notoriously unreliable (performance-wise) outside them. Thus tire choice is the perhaps the single most important decision made on race weekend.

In short, F1's new rule changes haven’t forced innovation and technology to take a backseat. In fact, FIA’s restrictive engine regulations have given the constructors impetus to advance the sport’s technology in several important areas. In respect to the 20% loss of power, the fact that teams have been able to equal (and in some cases better) last year’s lap times is nothing short of astounding, a testimony to the competitors’ tenacity and ingenuity.