Drag Racing Time Slip Scanner | Automatic Run Entry

How the time slip scanner works

The scanner runs a vision model that's been tuned on thousands of real time slips from NHRA, IHRA, and independent tracks across the United States. When you snap a photo from the Log Run dialog, the image is uploaded to secure storage and sent to the model with a structured prompt that asks it to identify each lane's column and extract every visible field.

Before the model runs, the app passes a few hints: your car's competition number, the racing class you typically run, and the list of every car number in your garage. The model uses those hints to pick which lane is yours when a dual-lane slip prints both racers side-by-side — instead of always grabbing the leftmost column like a naive OCR would.

The extracted JSON is sanity-checked on the way back. ETs have to ascend (60-foot < 330 < 660 < 1000 < final ET), reaction time has to be under 1.0 second, and trap speeds over 250 mph automatically convert from km/h if the slip is from an international event. If a value is illegible or missing, the model is instructed to omit it rather than guess — your fields stay blank for you to fill in or leave empty.

Fields captured from every slip

The scanner pulls every column a track printer typically writes, plus a few that only show up on certain formats:

• Reaction time (RT) — the green-light delta in seconds
• 60-foot ET — your launch indicator
• 330-foot, 660-foot (1/8 mile) and 1000-foot incrementals
• 660-foot trap speed (the 1/8 mile MPH column when present)
• Final ET — quarter mile or eighth mile, auto-detected from the slip
• Final trap speed (MPH) at the finish line
• Dial-in for bracket and class racing
• Lane (left/right) and car / competition number
• Run number, round (Q1/R1/SF/F), and event name when printed
• Date and time of day from the slip header (12-hour PM is auto-converted to 24-hour)
• Track name — fuzzy-matched against your saved track list and a database of 130+ sanctioned strips

Handwritten, faded, and unusual slips

Not every track still uses a clean thermal printer. The scanner handles dot-matrix, ink-jet, low-contrast carbonless, sun-faded copies, and full handwriting — including racers who write their own slips for test-and-tune sessions. Modern vision models read all of those formats far better than traditional OCR, which is what made manual entry the only realistic option for so long.

Two-lane slips with the columns smashed together are a common failure mode for legacy scanners. We handle them by asking the model to identify each lane's car number FIRST, then attach the correct timing block to each lane in the response. If the lane your car ran in printed a number that doesn't match any car in your garage, the app shows a one-tap disambiguation dialog: "Lane left was #1234, lane right was #5678 — which one was you?" That choice writes the right column into your run and remembers the wrong lane as a swap option in the edit dialog.

Batch scanning: multiple slips in one photo

After a full day of bracket racing you might have three to ten time slips stacked on the trailer counter. Instead of photographing each one separately, lay them out side-by-side in a single shot — the scanner detects up to twenty slips in one photo and queues them for you.

The flow is built around a simple queue. Snap the wide photo. DRL runs a cheap counting call first that returns how many distinct slips are in the picture — a single two-lane slip is correctly counted as ONE slip, not two, because two-up printed columns are NOT separate slips. Then the first slip is extracted into the Log Run form automatically. You review the fields, fix anything wrong, and the Save button relabels itself to "Save & next slip (2 of 3)". Hit save, the form pre-fills with the next slip's data, and you keep going. On the last slip the button returns to "Save Run" and the multi-slip badge clears.

The photo is uploaded to storage once at the start of the batch — every extraction in the queue reuses the same URL, so there's no bandwidth penalty for processing ten slips in a row. The car and track selection also persist across the queue (you're at the same event in the same car). Only the timing fields, lane, dial, and event-specific metadata reset between slips.

• Up to 20 slips in one photo (capped to guard against false positives).
• Processed left-to-right (then top-to-bottom for a grid layout).
• Each slip becomes its own saved run with the original photo attached.
• Per-slip toasts confirm the count: "Time slip extracted (slip 2 of 3) — 8 fields filled."
• Per-slip car / lane disambiguation: a wrong lane on slip #1 cannot bleed into slip #2.
• Fuzzy track matching runs per slip — a different track abbreviation on one of the slips still resolves correctly.

What happens when a field is missing

The model is instructed to omit fields rather than fabricate them. A printer that ran out of ribbon and ate the 60-foot column just leaves that field blank in the response. The app paints the populated fields with a brief green flash so you can see exactly what was captured, then it's up to you to type in any missing values manually. The rest of the run still saves — no all-or-nothing failure.

If your time slip didn't print a track name (some tracks print only an event ID), the app falls back to your saved "default track" or the nearest track by GPS, then asks you to confirm with a one-tap "Save this name as an alternate?" prompt. Next time the same slip format shows up, the match is instant.

Supported race formats

The scanner is calibrated for the formats American bracket and class racers actually run:

• Quarter mile (1320 ft) — the default, with 60/330/660/1000/ET/MPH columns
• Eighth mile (660 ft) — 60/330/660 ET + MPH, automatically detected
• Bracket racing with dial-in printed alongside ET
• Super Comp / Super Gas / Super Street index columns
• Junior Dragster slips (1/8 mile, no MPH column on some printers)
• Test-and-tune slips with no class field
• Two-lane heads-up slips where both racers' numbers print
• International slips with km/h trap speeds (auto-converted to MPH)

How scans connect to your other run data

A scanned time slip is half the story. The other half — the air, the engine vitals, the track — gets attached automatically. When you open the Log Run dialog, the app pulls the live weather for the nearest track (or the one you're at by GPS), computes density altitude, and pre-fills the atmospheric block. You can then snap a Kestrel or weather app screenshot to override it with what the staging lanes actually saw, or take a photo of the dash to capture oil, coolant, intake, and trans temps in one shot.

Once a run is saved, it feeds your car's ET predictor model. The next time you open the predictor at the same track in slightly different conditions, the regression already includes the run you just scanned. Snap a slip, save it, hit the predictor — the loop closes in about 90 seconds.