A worked lap comparison at Norwell

Read a measured lap comparison on Purple Sector’s public Norwell sample: lap times and speed, the timing basis, and what the evidence cannot prove.

By Purple Sector. Published 29 September 2026. Reviewed 14 October 2026.

The question: where does this lap lose time?

Lap 1 takes 1:07.371. Lap 3, the reference, takes 1:06.683. The recorded lap-time difference is 0.688 seconds. That total tells us which lap is quicker. It does not tell us where the difference accumulated, or what caused it.

This walkthrough uses the same comparison the public sample opens. Start with the totals, inspect one speed window, then decide which explanation the evidence supports. It is an analysis example, not a claim that a driver improved by the displayed amount.

A public sample, with a limited publication scope

The source is the Norwell recording already offered as Purple Sector’s public sample. No customer recording was used to create this article. The published evidence here is limited to sample lap numbers, lap times, relative distance, speed and a derived time comparison. We have not included pedal traces, driver names, account information or logger timestamps.

Opening your own recording or storing it in your account does not publish it in this guide. This page is generated from a fixed public example, rather than from the session library, customer accounts or support uploads. Read the privacy policy for the product’s complete storage and processing terms.

1. Check that the reference is a valid comparison

Both selected laps are complete flying laps from the same sample recording. Lap 3 is not the recording’s quickest flying lap: lap 15 is, at 1:06.049. The sample compares against lap 3 because that pair gives the clearest worked debrief. A reference needs to be a clean, comparable lap, and even the quickest lap is not automatically an ideal one.

Lap	Role	Recorded lap time
1	Compared lap	1:07.371
3	Reference lap	1:06.683

The 0.688 second difference is a comparison of two recorded laps, not a promised gain. For your own analysis, check the layout, timing basis, data quality and relevant conditions before treating another lap as a target. Different conditions can make a technically correct comparison a poor driving reference.

2. Inspect a speed window

The chart shows 480 to 730 metres from the sample’s lap start. It is a distance window through the slowing and acceleration visible in the speed trace, not a new surveyed corner boundary. Follow both lines from left to right.

Speed samples from the existing public Norwell example, resampled at approximately 11 metre intervals. The table below carries the values in text. Colours and line styles distinguish the two laps.

Measurement in this window	Lap 1	Lap 3
Lowest plotted speed	92.2 km/h	95.2 km/h

The compared lap reaches a lower minimum speed and remains slower during the following acceleration. That is something the plotted speed supports. Speed alone does not establish brake pressure, throttle position, steering angle or the reason for that difference.

3. Keep the timing basis attached to the number

On this article’s distance-resampled grid, lap 1 accumulates approximately 0.25 seconds of additional delay between 480 and 730 metres. This is a derived comparison of elapsed time at matching distance values. It describes that plotted window.

The workspace also aligns laps by GPS position for its time-loss budget. Equal distance does not always mean equal position when two laps take different lines. A window on this simplified chart therefore need not equal the workspace’s position-aligned corner cost.

The grid is spaced roughly 11 metres apart. Resampling and interpolation change small details; even its finish delta need not land exactly on the recorded 0.688 second lap-time gap. Use the recorded lap times for the whole-lap total, and the workspace’s labelled comparison for a corner-level budget. Do not add these different timing bases as if they were interchangeable.

4. Turn the observation into a question to investigate

A useful next question is: what differs through this slowing and acceleration window? Open the sample, confirm the selected laps, and compare the speed trace alongside its position-aligned timing view. The sample includes a prepared debrief so the measurements can be inspected in context; it does not run a new AI request.

For an own-file review, a lower speed may reflect a different line, grip, traffic, a setup difference or a driver action. Recorded inputs can help distinguish those explanations when they exist, but a speed trace cannot stand in for an absent pedal channel. This article intentionally stops at the published speed and timing evidence.

Only choose a driving change after the evidence supports its cause and it fits the conditions. A measured difference identifies a place to investigate; it does not prove that copying the quicker trace will be safe or quicker on the next lap.

What this example can answer

Question	Evidence available here
Which recorded lap is quicker?	The lap-time table answers this directly.
Where does the plotted time difference grow?	The distance window and its derived elapsed-time comparison locate a difference to investigate.
Did the driver brake too much or apply throttle late?	This published example contains speed, not pedal traces. It cannot establish either cause.
Will copying the reference improve the next lap?	No outcome is established by comparing these recordings. Conditions and the cause of the difference still need investigation.

Use the same sequence with your own recording: check the reference, locate the measured difference, identify the channels available, then separate the observation from a possible explanation. Keep an unanswered question when the necessary channel is missing.

Reproduce the comparison

Open the public Norwell sample.
Select lap 1 as the compared lap and lap 3 as the reference.
Check the lap-time totals against the table above.
Inspect Speed and the labelled delta around 480 to 730 metres. Keep the distance-versus-position alignment distinction in mind.
Use the Data panel to check what was recorded and what is derived. AI generation is disabled for this sample; the example debrief is prepared.

The article’s lap times and plotted series are checked against that bundled public recording in automated tests. If the measurement pipeline changes, those checks must pass before the example is published again.

Read the lap comparison guide, check the limits of GPS evidence or view the Norwell circuit guide.

Guides by logger: AiM (MyChron, Solo) · RaceBox · VBOX · RaceChrono · Harry's LapTimer · TrackAddict · MoTeC · Garmin Catalyst · GoPro · Alfano.