Road course · California, USA
Thunderhill Raceway Park
Thunderhill Raceway Park is a road course in California. OpenStreetMap maps one layout here, 4.58 mi (7.36 km). Below: the map, every corner with a computed line, the elevation, and where to stay and eat.
- 4.57
- Miles
- 37
- Corners
- 129
- Ft of elevation
01Track map
Thunderhill track map
Full circuit
Name inferred by TRACK from the mapped loops, not an official layout name.
- Mapped length
- 4.58mi
- 7.36 km
- Direction
- Counter-clockwise
- From OSM one-way tagging.
- Start/finish line
- Estimated
- Estimated by TRACK from the mapped geometry and not verified on site. TRACK asks you to confirm or move it before timing laps here, when you’re stopped.
- Corners
- 38
- Inferred from curvature, not official turn numbers
- Sectors
- 3
- Estimated, near each third of the lap
Source geometry: OpenStreetMap ↗. Something wrong? Fixing it in OpenStreetMap improves it for everyone.
02Overview
What Thunderhill is like to drive.
The full circuit layout at Thunderhill is 4.57 miles with 37 corners worth setting up for and about 129 ft of elevation change. A generic track-day car in our model brakes hard 31 times a lap and is at full throttle for about 38% of the distance; the longest straight runs roughly 1017 ft.
14 of the corners are slow (under 50 mph in the model), 6 are fast (over 75 mph). There are hairpins where exit speed matters more than entry. The corner notes below come from the mapped geometry, not from local knowledge; we’ll add a researched guide for Thunderhill later.
03Lap at a glance
Where the speed is, and where the hills are.
- Length
- 4.57mi
- Elevation range
- 129ft
- Steepest grade
- 11%
- Braking zones
- 31model
- Full throttle
- 38% model
- Longest straight
- 1017ft
The speed trace is a model, not a real lap: a generic track-day car (about 1.1 g of cornering grip, 1 g braking, 150 W/kg) driven on the computed line through an assumed 12 m wide track. Use it to see where the braking zones and flat-out sections are, not to predict your speeds. Elevation: USGS 3DEP 1/3 arc-second (NED 10 m) via OpenTopoData, sampled every 25 m along the mapped centerline.
04Corner by corner
The corners at Thunderhill.
TRACK’s own corner numbering (C1, C2…), found from the curvature of the mapped centerline. It isn’t the official turn numbering. Each diagram shows the computed line: the minimum-curvature path through an assumed 12 m wide track. It’s a geometric starting point. Your instructor’s line comes first.
- C1
Fast left-hander
↰ LeftfastcornerTRACK numbering
A fast left-hand corner that turns about 73°, tightening to a radius of roughly 71 m (233 ft). The model car brakes for about 175 m (574 ft), from 129 to 77 mph. The computed line turns in from the right side, takes a late apex, about 5 m after the corner’s geometric apex, and lets the car run out to the right on exit.
- Turns
- 73° left
- Tightest radius
- 71 m
- Model speed
- 129 → 77 mph
- Braking (model)
- 175 m
- Grade
- +1.8%
- C2
Medium left-hander
↰ LeftmediumcornerTRACK numbering
A medium left-hand corner that turns about 180°, tightening to a radius of roughly 53 m (174 ft). The model car brakes for about 75 m (246 ft), from 72 to 70 mph. The computed line turns in from the right side, takes an early apex, about 100 m before the geometric apex, and lets the car run out to the right on exit.
- Turns
- 180° left
- Tightest radius
- 53 m
- Model speed
- 72 → 70 mph
- Braking (model)
- 75 m
- Grade
- -1.0%
- C3
Medium right-hander
↱ RightmediumessesTRACK numbering
A medium right-hand esses that turns about 95°, tightening to a radius of roughly 51 m (167 ft). The model car brakes for about 135 m (443 ft), from 94 to 68 mph. The computed line turns in from the left side, takes a late apex, about 35 m after the corner’s geometric apex, and lets the car run out to the left on exit.
- Turns
- 95° right
- Tightest radius
- 51 m
- Model speed
- 94 → 68 mph
- Braking (model)
- 135 m
- Grade
- -1.9%
- C4
Medium left-hander
↰ LeftmediumessesTRACK numbering
A medium left-hand esses that turns about 70°, tightening to a radius of roughly 48 m (157 ft). The model car brakes for about 55 m (180 ft), from 82 to 62 mph. The computed line turns in from the right side, takes an early apex, about 40 m before the geometric apex, and lets the car run out to the right on exit.
- Turns
- 70° left
- Tightest radius
- 48 m
- Model speed
- 82 → 62 mph
- Braking (model)
- 55 m
- Grade
- +1.5%
- C5
Slow left-hander
↰ LeftslowchicaneTRACK numbering
A slow left-hand chicane that turns about 120°, tightening to a radius of roughly 10 m (33 ft). The model car brakes for about 65 m (213 ft), from 81 to 42 mph. The computed line turns in from the right side, takes a late apex, about 35 m after the corner’s geometric apex, and lets the car run out to the right on exit.
- Turns
- 120° left
- Tightest radius
- 10 m
- Model speed
- 81 → 42 mph
- Braking (model)
- 65 m
- Grade
- -0.5%
- C6
Slow left-hander
↰ LeftslowchicaneTRACK numbering
A slow left-hand chicane that turns about 146°, tightening to a radius of roughly 10 m (33 ft). The model car brakes for about 65 m (213 ft), from 81 to 42 mph. The computed line turns in from the right side, takes an apex close to the geometric apex, and lets the car run out to the right on exit.
- Turns
- 146° left
- Tightest radius
- 10 m
- Model speed
- 81 → 42 mph
- Braking (model)
- 65 m
- Grade
- -0.5%
- C7
Slow left-hander
↰ LeftslowchicaneTRACK numbering
A slow left-hand chicane that turns about 214°, tightening to a radius of roughly 10 m (33 ft). The model car brakes for about 65 m (213 ft), from 81 to 42 mph. The computed line turns in from the right side, takes an early apex, about 35 m before the geometric apex, and lets the car run out to the right on exit.
- Turns
- 214° left
- Tightest radius
- 10 m
- Model speed
- 81 → 42 mph
- Braking (model)
- 65 m
- Grade
- -0.5%
- C8
Medium left-hander
↰ LeftmediumcornerTRACK numbering
A medium left-hand corner that turns about 100°, tightening to a radius of roughly 53 m (174 ft). The model car brakes for about 95 m (312 ft), from 91 to 64 mph. The computed line turns in from the right side, takes an early apex, about 40 m before the geometric apex, and lets the car run out to the right on exit.
- Turns
- 100° left
- Tightest radius
- 53 m
- Model speed
- 91 → 64 mph
- Braking (model)
- 95 m
- Grade
- +0.3%
- C9
Fast left-hander
↰ LeftfastcornerTRACK numbering
A fast left-hand corner that turns about 44°, tightening to a radius of roughly 90 m (295 ft). The model car barely brakes here, carrying about 94 mph: a lift or a confident throttle balance. The computed line turns in from the right side, takes an early apex, about 20 m before the geometric apex, and lets the car run out to the right on exit.
- Turns
- 44° left
- Tightest radius
- 90 m
- Model speed
- ≈ 94 mph
- Braking (model)
- Lift / none
- Grade
- +1.7%
- C10
Fast left-hander
↰ LeftfastcornerTRACK numbering
A fast left-hand corner that turns about 46°, tightening to a radius of roughly 49 m (161 ft). It climbs through the corner (about 4% grade). The model car brakes for about 90 m (295 ft), from 113 to 81 mph. The computed line turns in from the right side, takes an early apex, about 5 m before the geometric apex, and lets the car run out to the right on exit.
- Turns
- 46° left
- Tightest radius
- 49 m
- Model speed
- 113 → 81 mph
- Braking (model)
- 90 m
- Grade
- +4.1%
- C11
Slow right-hander
↱ RightslowchicaneTRACK numbering
A slow right-hand chicane that turns about 40°, tightening to a radius of roughly 31 m (102 ft). It climbs through the corner (about 8% grade). The model car brakes for about 40 m (131 ft), from 74 to 45 mph. The computed line turns in from the left side, takes an early apex, about 5 m before the geometric apex, and lets the car run out to the left on exit.
- Turns
- 40° right
- Tightest radius
- 31 m
- Model speed
- 74 → 45 mph
- Braking (model)
- 40 m
- Grade
- +8.4%
- C12
Slow left-hander
↰ LeftslowchicaneTRACK numbering
A slow left-hand chicane that turns about 136°, tightening to a radius of roughly 15 m (49 ft). It climbs through the corner (about 5% grade). The model car brakes for about 50 m (164 ft), from 74 to 43 mph. The computed line turns in from the right side, takes an early apex, about 10 m before the geometric apex, and lets the car run out to the right on exit.
- Turns
- 136° left
- Tightest radius
- 15 m
- Model speed
- 74 → 43 mph
- Braking (model)
- 50 m
- Grade
- +5.2%
- C13
Slow left-hander
↰ LeftslowchicaneTRACK numbering
A slow left-hand chicane that turns about 131°, tightening to a radius of roughly 15 m (49 ft). It drops through the corner (about 8% grade). The model car barely brakes here, carrying about 47 mph: a lift or a confident throttle balance. The computed line turns in from the right side, takes a late apex, about 95 m after the corner’s geometric apex, and lets the car run out to the right on exit.
- Turns
- 131° left
- Tightest radius
- 15 m
- Model speed
- ≈ 47 mph
- Braking (model)
- Lift / none
- Grade
- -8.0%
- C14
Fast right-hander
↱ RightfastkinkTRACK numbering
A fast right-hand kink that turns about 25°, tightening to a radius of roughly 67 m (220 ft). It drops through the corner (about 5% grade). The model car barely brakes here, carrying about 91 mph: a lift or a confident throttle balance. The computed line turns in from the left side, takes an early apex, about 5 m before the geometric apex, and lets the car run out to the left on exit.
- Turns
- 25° right
- Tightest radius
- 67 m
- Model speed
- ≈ 91 mph
- Braking (model)
- Lift / none
- Grade
- -4.8%
- C15
Medium left-hander
↰ LeftmediumchicaneTRACK numbering
A medium left-hand chicane that turns about 102°, tightening to a radius of roughly 15 m (49 ft). The model car brakes for about 145 m (476 ft), from 124 to 55 mph. The computed line turns in from the right side, takes an early apex, about 5 m before the geometric apex, and lets the car run out to the right on exit.
- Turns
- 102° left
- Tightest radius
- 15 m
- Model speed
- 124 → 55 mph
- Braking (model)
- 145 m
- Grade
- -0.7%
- C16
Medium left-hander
↰ LeftmediumchicaneTRACK numbering
A medium left-hand chicane that turns about 122°, tightening to a radius of roughly 15 m (49 ft). It drops through the corner (about 2% grade). The model car barely brakes here, carrying about 66 mph: a lift or a confident throttle balance. The computed line turns in from the right side, takes a late apex, about 85 m after the corner’s geometric apex, and lets the car run out to the right on exit.
- Turns
- 122° left
- Tightest radius
- 15 m
- Model speed
- ≈ 66 mph
- Braking (model)
- Lift / none
- Grade
- -2.3%
- C17
Medium left-hander
↰ LeftmediumcornerTRACK numbering
A medium left-hand corner that turns about 90°, tightening to a radius of roughly 32 m (105 ft). The model car brakes for about 120 m (394 ft), from 87 to 54 mph. The computed line turns in from the right side, takes an early apex, about 10 m before the geometric apex, and lets the car run out to the right on exit.
- Turns
- 90° left
- Tightest radius
- 32 m
- Model speed
- 87 → 54 mph
- Braking (model)
- 120 m
- Grade
- -0.4%
- C18
Medium left-hander
↰ LeftmediumchicaneTRACK numbering
A medium left-hand chicane that turns about 70°, tightening to a radius of roughly 32 m (105 ft). It climbs through the corner (about 2% grade). The model car brakes for about 120 m (394 ft), from 87 to 54 mph. The computed line turns in from the right side, takes an early apex, about 50 m before the geometric apex, and lets the car run out to the right on exit.
- Turns
- 70° left
- Tightest radius
- 32 m
- Model speed
- 87 → 54 mph
- Braking (model)
- 120 m
- Grade
- +2.0%
- C19
Medium right-hander
↱ RightmediumchicaneTRACK numbering
A medium right-hand chicane that turns about 91°, tightening to a radius of roughly 45 m (148 ft). The model car brakes for about 50 m (164 ft), from 84 to 70 mph. The computed line turns in from the left side, takes an early apex, about 10 m before the geometric apex, and lets the car run out to the left on exit.
- Turns
- 91° right
- Tightest radius
- 45 m
- Model speed
- 84 → 70 mph
- Braking (model)
- 50 m
- Grade
- -1.6%
- C20
Medium left-hander
↰ LeftmediumchicaneTRACK numbering
A medium left-hand chicane that turns about 57°, tightening to a radius of roughly 52 m (171 ft). It drops through the corner (about 3% grade). The model car brakes for about 50 m (164 ft), from 84 to 70 mph. The computed line turns in from the right side, takes an early apex, about 10 m before the geometric apex, and lets the car run out to the right on exit.
- Turns
- 57° left
- Tightest radius
- 52 m
- Model speed
- 84 → 70 mph
- Braking (model)
- 50 m
- Grade
- -3.2%
- C21
Medium right-hander
↱ RightmediumessesTRACK numbering
A medium right-hand esses that turns about 34°, tightening to a radius of roughly 69 m (226 ft). The model car brakes for about 65 m (213 ft), from 99 to 73 mph. The computed line turns in from the left side, takes an early apex, about 15 m before the geometric apex, and lets the car run out to the left on exit.
- Turns
- 34° right
- Tightest radius
- 69 m
- Model speed
- 99 → 73 mph
- Braking (model)
- 65 m
- Grade
- -1.6%
- C22
Medium left-hander
↰ LeftmediumcornerTRACK numbering
A medium left-hand corner that turns about 81°, tightening to a radius of roughly 63 m (207 ft). The model car brakes for about 110 m (361 ft), from 99 to 68 mph. The computed line turns in from the right side, takes a late apex, about 20 m after the corner’s geometric apex, and lets the car run out to the right on exit.
- Turns
- 81° left
- Tightest radius
- 63 m
- Model speed
- 99 → 68 mph
- Braking (model)
- 110 m
- Grade
- -0.7%
- C23
Fast left-hander
↰ LeftfastchicaneTRACK numbering
A fast left-hand chicane that turns about 44°, tightening to a radius of roughly 73 m (240 ft). It drops through the corner (about 3% grade). The model car brakes for about 45 m (148 ft), from 96 to 76 mph. The computed line turns in from the right side, takes a late apex, about 55 m after the corner’s geometric apex, and lets the car run out to the right on exit.
- Turns
- 44° left
- Tightest radius
- 73 m
- Model speed
- 96 → 76 mph
- Braking (model)
- 45 m
- Grade
- -2.8%
- C24
Slow left-hander
↰ LeftslowhairpinTRACK numbering
A slow left-hand hairpin that turns about 172°, tightening to a radius of roughly 13 m (43 ft). The model car brakes for about 140 m (459 ft), from 96 to 33 mph. The computed line turns in from the right side, takes an early apex, about 10 m before the geometric apex, and lets the car run out to the right on exit.
- Turns
- 172° left
- Tightest radius
- 13 m
- Model speed
- 96 → 33 mph
- Braking (model)
- 140 m
- Grade
- +0.2%
- 13 more minor corners aren’t listed.
05Time it with TRACK
Drive Thunderhill. TRACK knows where you are.
No setup and no transponder. Start a session in the paddock and TRACK recognises Thunderhill and the layout from your GPS trace, then times every lap and sector with a live delta to your best.
- 1DetectTRACK matches your first few hundred metres against every mapped layout at Thunderhill, including shared pavement between configurations.
- 2Confirm the lineThe start/finish line here is estimated. When you’re stopped, TRACK shows it on the map: accept it or tap to move it. You’re never asked while driving.
- 3Laps, timed retroactivelyLaps you drove before confirming are timed from the recorded trace, so you don’t lose your first session.
- 4Go furtherSync a GoPro for video with telemetry and let TRACK Engineer point out where the time is. External 10–25 Hz GPS receivers for tighter sectors are awaiting hardware validation.
- Venue and layout detection is tested on simulated drives over real OpenStreetMap circuits, not yet in a real car. Compatible GPS receivers
06Plan your trip
Getting there, staying, eating.
Nearby places for Thunderhill haven’t been loaded yet.
07Track days
Find an open track day at Thunderhill.
TRACK doesn’t copy event listings. An on-page calendar will come with an organizer data partnership.
Before your first day here
08Nearby tracks
Closest mapped venues.
- Sonoma RacewayCalifornia · 95 mi away
- Southern Oregon SpeedwayOregon · 200 mi away
- WeatherTech Raceway Laguna SecaCalifornia · 207 mi away
- Buttonwillow Raceway ParkCalifornia · 319 mi away
Straight-line distance between venues. All 96 tracks
FAQ
Thunderhill, answered.
How long is Thunderhill?
The mapped centerline of Thunderhill Raceway Park is 4.58 mi (7.36 km) in OpenStreetMap. Published lengths are measured differently, so small differences are normal.
How much elevation change is there at Thunderhill?
About 129 ft (39 m) between the lowest and highest points of the full circuit layout, from USGS 3DEP elevation data sampled every 25 m. The steepest stretch is around 11%.
Which direction does Thunderhill run?
The main mapped layout runs counter-clockwise, from one-way tagging in OpenStreetMap. Check the event’s driver briefing: some venues run reverse-direction days.
Can I time laps at Thunderhill with my phone?
Yes, with the TRACK iPhone app (beta). It recognises Thunderhill and the layout you’re driving from GPS, then times laps and sectors. A phone’s GPS is good for lap times; an external 10–25 Hz receiver tightens sector splits.
Where is the start/finish line at Thunderhill?
TRACK estimates the line from the mapped geometry (usually beside the pit lane, or on the longest straight). It isn’t verified on site, so the app asks you to confirm or move it before timing your first session here.
How do I find track days at Thunderhill?
Clubs and organizers list HPDE, track days and club races on MotorsportReg. The venue’s own calendar lists its events too. TRACK doesn’t list events itself.
Where can I stay near Thunderhill?
This page lists hotels, campgrounds, restaurants, fuel and parts stores near Thunderhill from OpenStreetMap, with straight-line distances. Book early for big event weekends.
Track geometry and nearby places: © OpenStreetMap contributors, available under the Open Database License 1.0 (via the TRACK Atlas, snapshot 2026-10-17). Elevation: USGS 3DEP (public domain). Lengths are mapped centerlines, not official figures. The computed line and speed trace are a model. No start/finish line has been verified on site.
TRACK is not affiliated with or endorsed by Thunderhill Raceway Park, MotorsportReg or any business listed here. The venue name identifies the location only and belongs to its owner. TRACK shows no lap records or official results for this venue. Driving advice is general: your instructor, the event’s rules and the venue’s rules come first.