Help and contact for the SUTuner app.

Contact

Questions, bug reports, or feedback — email shop@skunkriverresto.com and we’ll get back to you.

Frequently Asked Questions

What jet size should I select?

SUTuner covers all three SU jet families: 0.090″ (HS2/HS4/HIF38), 0.100″ (HS6/HIF44), and 0.125″ (HS8, the big 2″ carbs used on cars like the Jaguar E-Type, Mark X, and XJ6, and the Austin-Healey 3000 Mk III). If you’re not sure which your carburetor takes, the Find tab shows which carburetor models are known to use each jet size once you select one.

How does Tune work?

Pick a needle you already have as your reference, choose a region of the needle (Idle, Low Cruise, Mid Cruise/Low Accel, Hi Cruise, Hi Accel, or the whole needle), and choose Richer or Leaner. SUTuner searches every needle in that jet/type family for ones that are consistently richer or leaner than your reference in that region — without going the wrong way anywhere else in it — and ranks them by how little they change everywhere else on the needle.

What’s the difference between the diameter chart and the flow area chart?

Diameter is the raw measurement. Flow area is the actual open gap between the needle and the jet at that station — it’s what fuel flow is really proportional to, not diameter directly. Richer and Leaner are labeled consistently on both charts even though the two values move in opposite directions as the needle tapers.

How do I import a dyno log?

On any needle’s detail screen, tap Import AFR Log and choose a CSV file with an AFR (or lambda) column and a vacuum column (inHg, MAP in kPa, or PSI) — RPM is optional. SUTuner places each reading by its vacuum value, since needle position tracks airflow/vacuum rather than engine speed, and plots it against the needle’s own station chart. You can keep multiple logs — one per needle you’ve actually tested — and compare them side by side.

Does the app work offline?

Yes. SUTuner makes no network requests of any kind — the needle database, vehicle applications, and any AFR logs you import are all stored on your device.