Laguna Seca MotoGP Preview

The 2012 MotoGP World Championship has become a three-way battle between Yamaha’s Jorge Lorenzo, the current points leader, and Dani Pedrosa and Casey Stoner, both on Hondas. All three have won at Mazda Raceway Laguna Seca in the past, and each of their machines has particular strengths.

The 2.24-mile, 11-turn circuit is the shortest on the MotoGP calendar, requiring 32 laps to make a race distance of just under 72 miles. It is a predominantly left-hand course, with seven lefts and four rights. There is a large elevation change, with a long climb from Turn 6 to the top of the famous Corkscrew, a tricky, steeply descending left-right.

The major setup compromise occurs right here, as teams seek to prevent front suspensions from bottoming in the hard pullout at the bottom of the Corkscrew, yet preserve the suppleness required to absorb the circuit’s signature bumps.

Traditionally, there is “Showa’s way” (supporting the machine mainly with spring) and the “Öhlins way” (using low-speed compression damping to absorb the pullout, allowing softer springing overall). For 20 years now, computer data from on-bike sensors has allowed this compromise to be most thoroughly studied and addressed.

As an example of the role of Laguna’s bumps, in 2002, Nicky Hayden and Mat Mladin accelerated out of the slow, left-hand Turn 11 for the final time. Hayden’s more-supple suspension setup absorbed the T11 exit bump easily, but Mladin’s firmer setup allowed his tire to spin, killing his drive and effectively giving the AMA Superbike title to Hayden.

Doesn't repaving take care of this? The track was paved in 2006 and 2007, but if the braking and acceleration of heavy racing cars are not the cause of bumps reappearing, then it must be "the bones of Mother Nature" asserting themselves, because the bumps always come back. Some of them are always on what would otherwise be the racing line, giving this circuit even more "character."

At this point, I have to mention Laguna’s perpetual probationary status. We think of the U.S. Grand Prix as a great and enduring tradition, but only MotoGP rights-holder Dorna’s eagerness for a foothold in the U.S. market has allowed the track to contravene important requirements. Separate ambulance access is required, but Laguna’s real estate cannot provide it. Local politics have always favored golf, art and expensive properties over motor racing. The area is expensive for visitors, limiting attendance. Laguna hosts only MotoGP and has not been required to run the full program, which includes Moto2 and Moto3. The imminent completion of a new track meeting all standards near Austin, Texas, makes it possible that the GP will soon depart the sere brown hills of Laguna.

Through much of this season, the pattern has been one of Yamaha dominance on circuits with continual turning and direction changing, with advantage to Honda when longer straights allow its stronger acceleration and top speed to be used. The exception was Germany’s Sachsenring, a turning course on which neither Lorenzo nor Stoner could find a definitive setup. Otherwise, the sharper onset of the Honda’s power has more quickly fatigued rear tires. Pedrosa said recently, “Normally, compared to Yamaha, we have some issues for the spinning, and we are looking to get a little bit more drive.”

Now, you may object, but doesn’t traction control automatically take care of all that? The answer is that the sharper the engine’s powerband, the harder it is for electronic systems and software to render it smooth enough to be usable from zero throttle. When the rider begins to throttle up in a corner, the bike is at full lean, with minimal extra tire grip available to handle engine torque. The smoother that torque is, the sooner the rider can begin to use it.

Why isn't it smooth? Don't we now have fine-atomizing, 12-hole fuel injectors providing excellent mixture formation? Yes, mixture preparation has never been better, but fuel/air mixture is not all there is in the engine's cylinders. At small throttle, the entering fresh mixture is diluted by exhaust gas. The harder the engineers have worked to build power, the more exhaust gas there is because a prime power-building tool is longer cam timings. With longer cam timing comes greater overlap—the period around TDC after the exhaust stroke when the intake valves are beginning to open but the exhausts have not yet fully closed. At the lower rpm of mid-corner, exhaust-pipe wave action is out of phase with piston motion, and so it blows exhaust back into the cylinders, diluting the fresh charge so much that sparks can't always ignite it.

The result is ragged running, as the cylinders take several cycles to accumulate enough fresh mixture to fire. That ragged running—cylinders missing, then firing and missing again—is transmitted to the rear tire, which can’t handle it. This forces the rider to delay throttle until he has lifted the bike up enough to produce the extra grip necessary to handle this rough torque. By that time, Lorenzo or Ben Spies or Andrea Dovizioso, able to apply their smoother Yamaha power earlier, may already have pulled alongside.

A concrete example of what low overlap can do is Ducati’s “Diavel” power cruiser. Its tiny, Honda Gold Wing-like 11 degrees of overlap give it strong, controllable torque from low rpm that would have a Suzuki GSX-R1000 or Yamaha YZF-R1 sputtering and bucking.

But when a race engine’s overlap is shortened, it can lose peak power. To prevent this, the engineers try to increase valve lift, but that may be impossible in high-rpm engines because the valves are already being opened so violently that they don’t last long. Current MotoGP rules give each rider six engines for the entire 18-race series, so reliability and performance are intertwined as never before.

Can’t the rider gear the bike to begin throttle-up at higher rpm, where the pistons and pipe waves are more in step, preventing inert smoke from being blown back into the cylinders? Sorry, we get only 21 liters of fuel for the race. The more time the engine spends at higher revs, making higher friction, the more fuel it burns.

How about variable valve timing, reducing valve overlap at lower revs? Sorry, it’s illegal in this class.

Wouldn’t it be grand if early acceleration could be delivered by a perfectly smooth electric motor, with the combustion engine taking over at rpm high enough to eliminate popping and banging?

Now, for the history: Here are the top-five finishers in the last five events at Laguna Seca:

Spec-tire provider Bridgestone began supplying asymmetric tires for Laguna in 2010 and will do so this year, as well. They comment that the wider temperature range of this year’s more-softly constructed “fast warm-up” tires will ease the Laguna problem of occasional high temperatures and normal cool mornings. Air and track temperatures (Fahrenheit) have been:

Before the present spec-tire era, Michelin based its Laguna Seca tire range on the hot conditions the year before. Nicky Hayden noted in 2008 that Michelin’s softest rear was much too hard, and Colin Edwards took desperate measures in an unavailing effort to get his tires to operating temperature.

Rider injuries have been frequent at Laguna, causing the comment that the several 90-degree turns require an "all or nothing" approach. A rider expects his tires to gain heat and grip through a longer turn, but in Laguna's "nineties," the situation, especially in the rights, is more like early laps on cold tires. You estimate what you think the tire can take, and then you bet all your chips on it. Or, you just go slow. In 2009, a novel kind of crash—the entry high-side—was much-discussed, and Lorenzo blamed the cooling of the tires' less-used right shoulders for this. In 2010, Bridgestone addressed this by providing asymmetric tires—slightly softer on the right, harder on the left.

Front tires are a component of good Corkscrew performance, as they carry extra-heavy load in the pullout at the bottom. Honda has had trouble with braking instability caused by the lower carcass rigidity of Bridgestone’s new “33” front tire. Higher inflation pressure can stiffen the tire, but the higher the tire pressure, the smaller the footprint. As a consequence, this reduced footprint reduces maximum corner speed.

About 20 years ago, there was some discussion within the tire industry of varying tire pressure “on the fly”—something that tire engineers regularly do with test tires on the drum tester. Lower pressure would allow extra footprint in turns, while higher pressure would cut heat-generating flexure on straights. The question is, how could you vary tire pressure hundreds of times per race, reliably?

What about Ducati, Valentino Rossi and Hayden? Ducati has been about to deploy some kind of new engine for some time, but its development has lagged. New parts could improve these riders’ placings, especially given Rossi’s recent strategy of springing last-lap passes on riders who were too busy racing each other to see the old master poised for an attack. Speculation also swirls around the idea that Rossi might rejoin Yamaha in 2013. That’s just what it is for now—speculation.

Race results come down to the accidents of the moment. If Lorenzo has a clear shot and the Hondas continue to be limited by chatter, braking instability and significantly faster loss of tire properties, he could make this look easy (it never is). But if, as so often happens, both Yamaha and Honda are up to their necks in problems that force a race-day setup gamble, a tight, can't-look-away contest could result.