IndyCar cars lined up in pit lane with crews and data cables, where team engineers download and stream telemetry from the spec Cosworth logger

IndyCar Telemetry Explained: Hundreds of Channels Out, Nothing In

October 21, 2026

Oct 21, 2026 · 7 min read·

IndyCar Telemetry Explained: Hundreds of Channels Out, Nothing In

Welcome to the Happy Hour Racing IndyCar Tech Breakdown - where we take one confusing part of IndyCar and make it make sense. No engineering degree required.

The Short Version

Every IndyCar is wired like a flying science experiment. Sensors all over the car feed a spec data logger, and that logger streams hundreds of channels off the car to the team's timing stand and to race control at the same time. But here is the part most fans never hear: that road only runs one way. IndyCar's rulebook flatly bans sending electronic data back to the car or the driver. Engineers can see everything and change nothing. The driver is the only one who gets to touch the car.

What Telemetry Actually Means

Telemetry is just a fancy word for "measurements sent somewhere else." A sensor measures something, and instead of only writing it down on board, the car radios that number to the pits in real time. Think of a smartwatch sending your heart rate to your phone while you run, except this version does it with hundreds of readings at once.

IndyCar runs a system built by EM Motorsport that went live across the series in 2023. It streams hundreds of channels off a small onboard antenna to the team and to race control, and all of it is handled right there at the track. The same hardware doubles as the series' electronic marshalling system, which is why one box ended up doing two jobs.

Meet the Parts: One Black Box for Everybody

IndyCar is a spec series, and that goes all the way down to the wiring. The rulebook says the only approved electronics for data logging is the Cosworth Omega system, and then it names the pieces:

Central Logging Unit (CLU) - the brain that collects and records everything.
Removable Logger Unit (RLU) - the part engineers pull and plug in to pour the session's data onto a laptop.
Synchronous Junction Unit (SJU) - the hub that keeps all those signals lined up in time.
Configurable Display Unit - the screen on the steering wheel the driver reads.
Intelligent Power System (IPS32) - the electrical panel that feeds the rest of it.

All of that hardware has to run IndyCar-specified firmware and software. Teams are allowed to design their own steering wheel, but they must build the approved Cosworth display into it. Nobody gets a smarter box than anybody else.

Data flows out of the car in two directions at once. Nothing electronic is allowed to flow back in.

The Sensors Teams Are Actually Allowed to Run

Teams cannot just bolt on whatever they want. Three sensors have to come from an approved supplier list: the throttle pedal sensor, the front and rear pushrod strain gauges, and the wheel speed sensors. On a race weekend the rulebook then spells out the legal extras, including tire pressure, brake pedal position, laser ride height, roll bar and weight jacker position, gyros, temperature sensors, and a limited count of accelerometers - two three-axis units on the chassis and one per corner at the hubs.

There is even a line banning an underwing pressure tapping, a sensor that would read the air pressure under the floor. Since the floor tunnels make most of an IndyCar's grip, that is exactly the number a team would love to have and exactly the one the series will not let them chase on a race weekend.

At open tests the leash gets longer. Extra sensors are allowed as long as they fit inside the bodywork, with one catch that tells you who is in charge: all the data has to be provided and visible to IndyCar.

The Rule That Changes Everything

Here is the sentence that defines IndyCar racing more than any other line in the electronics section: electronic data of any type may not be transmitted wirelessly to a car or driver.

That is why the in-car radio is deliberately old-fashioned. It has to be analog voice in the 450 to 470 MHz range, narrowband, and the rulebook says it must not be capable of transmitting or receiving in a digital format. It cannot be encrypted or scrambled, because IndyCar has to be able to scan and listen at any time. So a race engineer who sees a problem in the data has exactly one tool: a human voice telling a human driver what to do about it.

The rulebook closes the side doors too. Electronic logic processors cannot control car functions or interrupt the driver's inputs, except for the approved control units that run the engine, clutch, gearbox and weight jacker. A single driver input cannot trigger multiple control functions, so you cannot build one magic button that does three things at once. Teams cannot even plug into the car after qualifying or the race until IndyCar releases it.

The split that keeps IndyCar a driver's series: the team may talk, the series may signal, and nobody may reprogram the car from the pits.

The One Exception: Race Control Can Talk to the Car

The ban applies to teams. IndyCar itself does send signals to the cars, and you can see them. The series triggers the EM marshalling system, which lights up the black flag, the full course yellow and the local yellow directly on the driver's dash. That matters on a street course where a driver may not see a corner worker in time. On road and street circuits the Push to Pass enable signal also comes from the timing and scoring beacon on board, and the rulebook requires teams to pass that signal to the engine control unit unmodified and uninterrupted.

IndyCar cars racing at Road America in 2025 beneath a video board showing live timing and scoring data with lap count and gaps — The board above the cars at Road America is the fan-facing end of the same pipeline: lap count, running order and gaps to four decimal places, pulled off the cars in real time. (Photo: Michael Barera, CC BY-SA 4.0, via Wikimedia Commons)

Why the Data Is Also the Referee

All those channels are evidence. Teams must upload a complete Cosworth dataset containing their fastest lap within one hour after the first practice, qualifying and the final practice. Engine manufacturers have to send their engine control unit data in the same window whenever an IndyCar-owned hybrid is used.

The 2026 season showed how that gets used. At Long Beach in April, simultaneous CAN messages from IndyCar's own software reached the cars incorrectly, so the signal that shuts Push to Pass off never arrived and twelve cars used it on the Lap 62 restart. Officials reviewed all twelve, found the only position change was car No. 66 getting past car No. 14, and issued no penalties because the failure was the series' own. IndyCar then added a software "lock" so those messages can only be sent one at a time, expanded Push to Pass availability on restarts, and rewrote the rule so competitors carry the responsibility. The new language says violations are determined from engine control unit data, timing data, or any other available telemetry, and that such data is sufficient evidence.

What You Will See on Track

Listen to a race broadcast with this in mind and it sounds different. When an engineer says "we need two clicks of front bar," that is not a suggestion being beamed to the car - it is a person asking a driver at 180 mph to reach down and move a lever himself. When a team spots a temperature climbing, all they can do is talk. And when a driver's dash flashes yellow before he can see the crash, that is the series, not the team, reaching the car.

The Bottom Line

An IndyCar tells its team everything and takes orders from nobody but its driver. Hundreds of channels go out, zero come back, and that gap is where the racing lives.

If this is your corner of racing, the IndyCar gear is over here.

Sources: the 2026 NTT INDYCAR SERIES rulebook (Sections 7.4, 14.3, 14.19 and 14.20), INDYCAR Officiating's Long Beach Push to Pass findings, and INDYCAR's announcement of the EM Motorsport telemetry system.