Most of my columns focus on driver skill, because that’s the most important factor to becoming faster on the track. However, with track season approaching, many people wonder what they can do to their “cars” to improve their lap-times. Most people, myself included, set some money and time aside to make “improvements” during the off-season. Of course, safety improvements should always be considered prior to performance improvements. Injury or death is far more unpleasant than being half a second slower.

So, what are the best performance upgrades to do to your car? You’ll hear many suggestions running the gamut when you ask around. But, I suggest a more analytical approach. By breaking down the desirable attributes of race cars, and giving each one a score, we can evaluate performance upgrades to determine if some offer more “bang for the buck” than others.

Racetracks, by their nature, are a series of straight segments and corners. The majority of race tracks have more “straight” pavement than “curved” pavement. This means, more time will be spent on the straights than in the turns. Because of this, linear acceleration is the most desirable attribute for a race car. The more linear acceleration you have, the faster you’ll be able to get to the next turn. Let’s give linear acceleration a score of 5 points.

For every action there is an equal an opposite reaction – linear deceleration is the opposite of acceleration. Being able to slow the car down as quickly as possible is a close second to linear acceleration.We want to spend as little time as possible on the brakes because that will give us more time to be on the gas (ever hear “more gas, less brakes”?), so let’s give linear deceleration a score of 4 points.

That pretty much uses up the straights, now we move onto the corners. Cornering power – our ability to carry speed through the corners – is the next important attribute of a race car, and deserves a score of 3 points.

Controllability, how well the car can handle upsets in weight transfer and how well the car responds to corrections from the driver, is the next player in our equation with a score of 2 points.

And finally, top speed, which really plays quite a small factor in most production sports cars, is our final scoring element at 1 point.

Now that we have our grading criteria, we can plan our upgrades. Let’s compare a horsepower increase, from a performance ECU chip and an after-market exhaust, to stickier R-compound track tires. The HP upgrades will get more power to the rear wheels, propelling the car down the straights quicker (linear acceleration at 5 points) and will increase the top speed (1 point), giving it a score of 6 points. The increased traction of the track tires, however, will increase cornering ability (3 points) and will increase braking ability (linear deceleration at 4 points). That gives the track tires a total score of 7 points – higher than the power upgrades. If both modifications cost about the same, the track tires have more potential to reduce lap times. This also explains how some cars, although slower on the straights, can turn faster lap times.

Let’s look at some other examples: brake upgrades (linear deceleration) = 4 points; corner balance and wheel alignment (cornering power and controllability) = 5 points; spring/shock upgrades to improve weight transfer characteristics (cornering power and controllability) = 5 points; reducing aerodynamic drag (linear acceleration and top speed) = 6 points; reducing total vehicle weight (linear acceleration and cornering power) = 8 points; upgrading to a limited slip differential (controllability) = 2 points.

Now, it’s important to point out that this is all on a relative scale – not an absolute scale. It’s improper to say, “Removing my rear view mirrors will reduce my aerodynamic drag, so that’ll make me faster than putting in a limited slip differential!”What this grading system is supposed to analyze is what modifications have the “potential” to offer the greatest reward. If you can make a 911 have the aerodynamic characteristics of a formula car, that would make a larger difference in lap times than anything you could do with the differential. However, the controllability increase of an LSD will be more noticeable than minor aerodynamic enhancements.

Similarly, reducing weight to reach a target horsepower-to-weight ratio, rather than increasing engine performance to reach the same ratio, will yield the faster lap times.

Plan your winter modifications carefully and next time we’ll focus on getting more out of your (now faster) car by improving the driver.

I’ll meet you at the apex!
Van Svenson