Spool BMW Gen 1 B58 Wireless Ethanol Analyzer Kit
The Spool wireless ethanol analyzer displays the actual ethanol content and fuel temperature on a smartphone. It is especially useful on cars running E85 or custom ethanol blends where the calibration expects a known ethanol percentage.
Fuel sold as E85 does not always contain exactly 85% ethanol. Spool notes that E85-rated fuel may contain roughly 51–85% ethanol, so measuring the fuel in the tank removes the guesswork when preparing a blend.
How it works
- A GM/Continental-type ethanol sensor measures ethanol content and fuel temperature
- Bluetooth Low Energy sends live data to the phone with very low power consumption
- The free Spool app shows the reading and includes an ethanol mix calculator
- Vehicle-specific fittings and adapters allow a clean installation with the factory fuel lines
This is a useful addition to a tuned car where fuel composition directly affects the calibration and safe engine operation.






