The 25 Hours of Thunderhill is a race that remains far more grueling than the Rolex 24 at Daytona. Why? Because—in an event designed for amateurs—shit breaks, people crash, drivers sleep in freezing trailers (not $500,000 RVs), and blind corners hide many wayward Miatas.

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The closing speeds between those Spec Miatas and the prototypes are ludicrous. And unlike Daytona at night, where giant floodlights make headlamps redundant, at Thunderhill, it’s like being thrown into “The Hole” at Alcatraz.

The past two years I’ve raced the 25 Hours, competing at Thunderhill Raceway in Willows, Calif. The first time, in a Norma M20F, we won the overall. The second, in a custom 700 horsepower machine known as “The Beast” (see above) we suffered endless mechanical gremlins.

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Still, I’ve garnered plenty of experience at the track, and now I’m going to share the secrets for getting around it quickly.

(A quick word of caution: I’ve only driven Thunderhill in high horsepower, lightweight race cars. Naturally, if you’re driving a street car, things could be slightly different. So take this as food for thought, not a definitive guide.)

Turn One: A perilously fast left hander where balls the size of grapefruits are required. In a prototype, you’re approaching the braking zone at approximately 160 mph.

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No matter what car you’re in, this is a momentum corner. You want to lift early, brake lightly, and role speed down to the apex. The exit is blind, so you must sense how early you can get back to full power. Time, here, is gained on entry. With a downhill exit, an overly hot entry lacks the punishment typically dished out.

I’d typically want to turn in even earlier than this to dive-bomb the corner

Turn Two: Approach it with a similar mindset to T1, only the radius of the corner is far longer. I treat this as a double apex, turning in early, carrying a boatload of speed, letting the car run out to the middle, and then pinching it back to the inside for corner exit. You’ll need a car with a stable rear-end on entry, and any trail braking you do should be gentle to keep the car’s platform level.

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But think entry speed and exit speed—screw the middle. Having said that, as soon as you can you want some level of maintenance throttle. This is a longer corner where maintaining a solid minimum speed is a must. On the exit, you can use all the track and still make it back to the left for corner three.

Turn Three: Keep the momentum up, turn in late, and hold the car just right of the track’s center line on exit (see pic above); don’t feel the need to go further right than this in preparation for the following left. On entry, the car will go light as you go over a small, off-camber crest. Watch the rear of the car here.

Turn Four’s mindset should be exit speed, knowing that you’re about to climb the mother of all hills into five.

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Turn Five: Thunderhill’s most infamous turn. Basically you turn right over a hill so steep it would be more at home on a ski resort than a racetrack; the sensation is akin to that of a rollercoaster. I can’t think of any turn like it, anywhere in the world. In a prototype, you practically jump over the crest. And when you resurface, the compression is like having three Seth Rogans sat on your head.

Once over the crest, the pole on the right is a good indication of the apex

The concept here is momentum, much like most of the initial part of the lap. Aim for the thin plastic pole on the left as you approach, lift early, slow the speed down, and then pick up maintenance throttle before you crest the hill.

This keeps load on the rear tires which ensures the car remains stable. Once you’re over the part where the car goes light, use the compression to get back to full power sooner than you might think. Patience would seem to be the key here, but in reality, a gung-ho approach can yield significant lap time. (People are nervous of sketchy corners. So take advantage.)

Exiting five you’re edging your way to the right for Turn Six. Don’t feel the need to get all the way over. Brake early, turning in later than average and apex just after the curbing appears on the inside (see above). Aggressively return to power as soon as possible. Be gentle unwinding the wheel. You can use the curb at apex, as shown, as well as on the exit.

The first kink, Turn Seven, is comfortably flat. In “The Beast,” Turn Eight (above) was a butt-clencher, mainly because that car had a habit of wanting to strip your flesh and feed you to the neighboring mountain lions. Keep the momentum up, scrub as little speed as possible. Use the curb on the exit and be brave.

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The nice thing with Thunderhill is that, if you crash, you’ll often find yourself in Tahoe before hitting anything. The bad thing: During the race in December, it rains often; the grass is so muddy your car would appear better if it were run over by Grave Digger.

So blind it’s a Wonder we ever make it though (see what I did there?)

Turn Nine is a badass left-hander that goes up and over a crest. It’s tight, but you can carry a surprising amount of speed. Uphill braking ensures you wait until the last moment, but the blind exit takes time to fully understand the line. You’ll see the protruding posts seemingly marking the edge of the track to the right. Don’t use these as a reference. Keep a good 15 feet to left or you’ll run out of room. Give yourself some space to breathe. If you do run wide here, you probably won’t be returning.

Up the gears, down the hill, and to Turn 10. The slope means you must brake earlier than you think; watch for the rear to get light under heavy braking. As with nine, you can carry a crap-ton more speed than you expect. The tarmac typically boasts good grip here, and you should use it.

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While tight, this is a bend that always makes you scream, “Dammit, I coulda’ done more.” Time is gained by pushing the braking as deep as you can; there’s nothing to be gained by setting yourself up for a good exit.

Don’t do what the Porsche did. Use every inch of available road

From third gear, you immediately drop down to second for the tightest corner on the track, Turn 11. Apex late, and focus on exit speed; you’ve got a long straight ahead. Out of 11 there’s a right then left. “The Beast” required an early, gentle lift in the right, then flat through the left. The Norma was easy flat through both. Whatever you’re in, use all the inside curb on the right hander (see above), keeping tight up against the tires. Be smooth and scrub as little speed as possible.

Start thinking about braking for the final bends—Turn 14 and Turn 15—as you rocket under the bridge. Brake as late as you can. Use all of the apex curb, along with all the track out of 14—and then some. This opens up 15; you want to be as close to flat as possible, leading onto the track’s longest straight and passing the start finish line.

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That’s a lap of Thunderhill. It’s a place that takes time to master, and it requires a lot of commitment. The blind corners, the speed, the crests—it’s as challenging a track as there is in the U.S., and when combined with 80 other cars with wildly varying speeds—and drivers with vastly different experience levels—the challenge is only magnified.

Once you get it, however, you can find a lovely rhythm. In the dark, all reference points are gone, but you somehow dance around like Sammy Davis on his tippy toes, the beams of light almost mystical in the fog.

If you get the opportunity, go race the 25. But remember: you can’t pass at turn seven’s kink. Unless you’re planning an impromptu trip to Tahoe.

Also, I’m aware this may have been a bit technical for some, but fear not: Next time I’ll talk about that time I threw up Mexican food in Eliseo Salazar’s Aston Martin.


@Alex_Lloyd is Head of Content at Beepi, a radically transparent and easy way to buy, sell and lease cars online. A racing driver who competed in the Rolex 24 at Daytona twice and the Indianapolis 500 four times, his column Three Wide is about the culture of speed.