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Thunderhill Park Raceway is a 15 turn, 3 mile road course which can be divided into two shorter loops, a west loop of 1 mile and an east loop of 1.6 miles. It is an SCCA owned and operated facility, run by the SCCA's San Francisco Region. Located on 540 acres of rolling hills off I-5 in California's central valley, it is located about 75 miles north of Sacramento. The residents of the nearby town of Willows welcomed the new racing facility and the local business which it attracts.
The original version of this page was contributed by Mark Magee.
Last Updated: 2005-04-09
The original configuration of the track (introduced in 1994) was a 1.9 mile long counterclockwise loop, with limited paddock area. For 1999, the track was lengthened to 3 miles and the paddock was expanded.
| Allan E. Brown, The History of America's Speedways: Past & Present. Comstock Park, Michigan: Brown, 2003 , ISBN 0931105617 , pp. 168. Order from National Speedway Directory |
This map shows the original course
and the planned expansion, which has since been built.
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From the San Francisco Bay Area, take I-80 east to I-505 north and then to I-5 north. Exit in Willows on Highway 162, and head about 6 miles west of town to Thunderhill. Rumor has it that 162 is patrolled on event weekends.
The following hot lap (by Mark Magee) is of the original course, and is a description of a qualifying or school line. A racing situation will require a more defensive line through some corners.
Exit pit lane to the far right. Watch for oncoming traffic setting up for the left-hand turn 1. Don't turn-in too late at 1 or you will get out in the marbles and have bad camber as well. The apex to 1 is mid to late. A mild rise near the apex will lighten the car. The exit is near the end of the burm on the outside. There may be a drop-off at the edge of the track after the burm where cars have dug a rut in the dirt.
There is a short, slightly downhill straight leading up to turn 2, a long, wide carousel with a very late apex. This is a very good turn to work on the limits and the balance of the car. There are some bumps in the beginning 1/3 of 2. There are a couple lines to avoid the bumps. Formula cars like a tight line. Street cars like a wide line, about 2/3 away from the inside edge. The apex is a bit hard to see from the entrance, but the black pavement patches on driver's left can be used as reference points in lining up the turn. After clipping a late apex, drift out to the burm on driver's right. Near the end of the burm is a good spot to exit.
Now quickly get back across to setup for the right-hand turn 3. Move to about 1/3 the track width away from the edge at drivers left. There is a bit of a crest leading to the entrance of the turn. Braking should be done before the crest. The turn itself is very late apex and significantly off camber, so the entry will probably feel a bit slow. Take a gentle arc to a very late apex, using gentle throttle application to avoid excessive power slide. The apex is hidden by the hill, but there is a small white concrete patch in the asphalt which can be used as a mid-turn reference point. Turn 4 is a fast left-hander, so 3 is sacrificed with a very late apex to setup for a good entry to 4. The transition must be fast and smooth. Don't toss the car through here.
Some cars may need slight braking out of 3 to set up for 4; others can be flat. The apex for 4 is late. At the entrance, look through the apex and up the hill to the entrance to 5. This will help keep a nice, straight stable line out of 4 and into 5.
Turn 5, a.k.a. the Cyclone, is where you learn to trust your corner workers. It is reminiscent of the Corkscrew at Laguna Seca, but is faster and blinder. The Cyclone consists of a sharp left-hand turn at the top of a ridge followed by a right-hand off-camber sweeper. Brake in a straight line coming up the hill, downshift to second, and turn in early, perhaps sooner than feels right. Begin to straighten and sqeeze the throttle as you crest. If you have aimed correctly, you will be against the burm on drivers right on the way down. This is a good place to grab third. Modulate the throttle through the right-hand sweeper, drift out, but bring the car back to driver's right to set up for the left hand turn 6.
Turn 6 may call for some lift to settle the car. Turn in and aim for a late apex. Throttle steer through the apex out to the exit burm. The exit is about 1/4 from the end of the burm. Exit speed is very important because 7 is really a long dogleg straight.
As you exit 6, pick up the entrance to 8 to guide your line through seven. Turn 8 will call for the heaviest braking on the course. Turns 8 and 8A should be taken as a single turn. The best line may be to take it a little wide at the "apex" of 8, focusing on hitting the true apex at 8A. The real key through this set of turns is to get the throttle down early.
It's very important to get a good run through 9 for a fast exit speed onto the main straight. Turn 9 has a drop near the apex as the curved section transitions onto the flat straightaway. This can upset the car, so pick your line carefully. There is plenty of run-off room at the exit of nine. If you need it, use it. Jerking the car back on track will hook you across the track into the only armco on the track -- the pit wall.
As you exit 9, watch for cars slowing to get to the pit entrance over on driver's right. This is a good time to check your guages. As you pass start-finish and the end of the pit wall, you will want to move to driver's right to set up for turn one. Watch for cars entering the track.
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