Excellent article, and it was fun to go back to my Calc-based Physics days for a moment. I'm lying there, actually...

To me, the article was a bit wordy in places it shouldn't have been. The example of the flywheel "theoretically" making a 100hp car do a ten second 1/4 mile was simply extra fluff that distracted from the whole lot, and that scenario would only exist on paper.

Particularly with the part on braking, I think he focused too much on the part about lighter rotors making you stop better. They don't, and I'm not aware of any racer that has purchased lighter brakes with the intention of stopping harder from weight savings alone. Where the bigger, lighter brakes DO come in handy is the heat dissipation, and the more pistons you use to clamp down on the rotor with, the bigger hat you need for said braking (also to simply fit the pistons). Interesting points he made about the lugs being negligible, as I have always thought this and I've seen vendors selling "ultralight" titanium lug bolts for use with lightweight wheels... Now I know it's $500 down the drain.

Let us also remember that the wheel isn't the ONLY thing spinning on the hub during acceleration... So if you save 5 pounds per corner on a new wheel and tire setup, and ~7 pounds on each corner in rotor hat weight, then you've effectively shed 96 pounds of static weight from the car, using these numbers. 96 pounds may only mean an improvement of .1 second in the 1/4, assuming all other factors remain constant, but it's the other 99% of the time your machine is in action that the biggest gains will be realized.

While the number doesn't seem huge, think about this: each and every time your suspension cycles (as in, EVERY bump that you encounter), it has to move the attached weight back and forth on an arc. It is at the limits of the arc that the greatest effect from the weight is felt... pick up a fifteen pound barbell and hold it straight out from your body. Now, rotate your torso back and forth as fast as possible, trying your best not to move your arm. Rotate from the 10:00 position to the 2:00 position 50 times. Try this same experiment again with a 6 pound barbell, and note the results.

Your car doesn't have muscles that fatigue, but mass is mass and this all plays an effect on shocks, bushings, tie rods, ball joints, etc... a machine that has to work harder to achieve the same results will be slower than one that uses lighter components.

Les can attest to the fact that having lighter components is FAR more than simply going in a straight line the fastest... it's about endurance, agility, and the ability to do the cycles thousands of times with as little stress on the machine as possible.

Interesting also about the comment near the bottom regarding low-profile tires... since the entirety of the tire's weight is concentrated at the end of the rolling stock's radii, it's easy to see why a narrower drag radial on a smaller diameter wheel nets better straight-line acceleration... couple that with the issues of sidewall flex, wheel weight of a 19" wheel versus a 16", etc... it all comes to play nicely together. Once at speed (refer back to his flywheel equations), it matters less and that's why a road course car benefits more from a low-profile, wide tire since there is more tread available for lateral forces (and the sidewall it's attached to doesn't flex nearly as much as the sidewall on a wheel and tire combo with same OD but smaller rim and higher aspect ratio tire).

On that last point, it's one of the reasons why the N/A cars make horrible drag racers, but excellent corner carvers: that big 19" wheel is a torque robber and a bear to get rolling off the line, hence the bogging effect on any launch < 4,000 RPM... But once rolling, we can hang with many of the big boys, because the car simply bites the road in the corners with the minimal sidewall flex. As you decrease the wheel's diameter, you improve the 1/4 mile capabilities but steal from the other hand on the handling abilities. Since the N/A is already at a huge horsepower deficit, it's why many owners tend to modify their cars to tackle the corners, not the strip. We build off the platform we already have a head-start on.

A good read indeed.