Engine RPM vs Microdyno

Measure the RPM of an engine by analyzing the sound it makes. Engine RPM listens to the sound of a running engine and uses advanced signal processing algorithms to extract the frequency of that sound and calculate the RPM. This app is primarily for setup and diagnostics of engines. After setting the the number of cylinders and whether the engine is a 2-stroke or 4-stroke engine, the app can work with any internal combustion engine, from diesel tractors to aircraft engines to motorcycles to chainsaws. To use the app you must set an expected RPM range to guide the analysis algorithms to the correct RPM. A real-time graph of the autocorrelation graph is displayed to help in troubleshooting and adjusting the expected RPM range. The analysis requires a clear sound from the engine without excessive interference from extraneous sounds. Do not expect to read the RPM of an engine while other things are making too much noise at the same time. The analysis also requires that the RPM be stable. It cannot read the RPM of an engine that is rapidly accelerating. For this reason, and because of the need for adjusting the expected RPM range, this app should not be considered a drop-in replacement for an operational tachometer. Setup options include update periods from 93 milliseconds to 1.5 seconds, one to 12 cylinders, 2-stroke or 4-stroke, low-pass filtering, and signal clipping. The overall RPM range is 400 to 90,000 RPM (although at any one time, the operational range is typically +/- 30% around a nominal expected RPM). Precision is usually about +/- 10 RPM.

Microdyno measures the power and torque of your motorcycle or scooter with your phone. From the rpm trace of an acceleration run in a chosen gear, the app calculates the curve the way a chassis dyno does, only on the road. Three ways to get the rpm • Microphone: The app reads the rpm from the engine note. In the spectrogram editor you see the fundamental and its harmonics and erase any noise that gets in the way. • Microdyno rpm sensor: A small Bluetooth sensor on the ignition lead reports every spark. No noise, no steps, the most accurate curve. • Lambda sensor: Wideband probe with the AFR trace over rpm. Live while riding as a floating window (Picture in Picture), and in the analysis with map and audio playback. Analysis • Power, torque, rpm and speed as curves, peak values at a glance • Trim the run at the markers, remove outliers, smoothing in three levels or, in expert mode, as a freely combinable chain • Correction to DIN 70020 or SAE with temperature, pressure and humidity, fetched from the weather service on request • Compare runs, with a mean curve over several runs • Vehicles with gearbox, ratios, tyres, weight and driving resistances. Over 100 templates from the Vespa smallframe to the motorcycle Cloud and browser • Sign in with Apple, Google or e-mail and your recordings, results and vehicles stay in sync across your devices • Web app at app.microdyno.de: open, trim and analyse recordings in the browser, download the files • Without signing in, everything stays on the device How it works 1. Create a vehicle or pick a template 2. Mount the phone, connect the sensor or use the microphone 3. Start recording and accelerate through the chosen gear 4. Trim the run, save the result, compare Who it is for Vespa and scooter riders, motorcycle tinkerers, tuners and workshops. Anyone who wants to know what an exhaust, a carburettor setting or a new cylinder really does. Accuracy The calculation is checked against dyno measurements. Repeatable results need equal conditions: same gear, same stretch of road, warm engine. Absolute figures depend on the weight and driving resistances you enter. For before-and-after comparisons on the same vehicle that does not matter. No subscription, no hidden costs. The app is under continuous development. Questions and requests to stefan@microdyno.de.