Ethanol Analyzers & Flex Fuel Kits

Ethanol analyzer kits from Spool Performance. An ethanol content sensor reads the ethanol percentage of the fuel in the line so the tune can adjust for E85 or mixed blends. Most kits here are Spool wireless...

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About Ethanol Analyzers & Flex Fuel Kits

Ethanol analyzer kits from Spool Performance. An ethanol content sensor reads the ethanol percentage of the fuel in the line so the tune can adjust for E85 or mixed blends. Most kits here are Spool wireless analyzers, and some include a fuel filter.

Listings cover BMW N20/N26, N54/N55, B58 Gen 1 and Gen 2, S55, S58 (G80, G82, F97, F98) and S63 (F10 M5, F90 M5, M8), Mercedes-AMG M157, M177, M178, M276 and M278 models, the Audi C8 RS6 and RS Q8, Lamborghini Urus, McLaren 570S/600LT and 720S/750S/765LT, Porsche 992 GT3 and the Aston Martin Vantage V8. Check the engine and chassis in the title before ordering.

See all fuel system upgrades or the Spool Performance range.

Frequently asked questions

Do I need an ethanol analyzer to run E85?

It measures the real ethanol content in your tank and shows it, with fuel temperature, on your phone. Fuel sold as E85 can contain 51% to 85% ethanol, and the listings warn that running less ethanol than your tune expects can damage the engine, so an analyzer is the practical way to check. See our ethanol analyzer guide.

Does the analyzer change my tune automatically?

The analyzer measures and reports ethanol content. Some kits, such as the RS Q8 and Urus kit, are described as working with flex-fuel tunes, but whether your tune uses the reading depends on your tuning platform and setup. Ask your tuner before you buy.

Where does the sensor go?

In the low-pressure fuel feed, between the tank and the high-pressure pump, so all fuel heading to the engine passes through it. Kits are model-specific because line routing, fittings and harness connections differ, and some Mercedes kits include a 10-micron filter.

Can I use the mix calculator without the kit?

Yes. The listings say the Spool app's ethanol mix calculator works without the kit, but you then enter the ethanol content yourself. With the kit fitted, it fills in your current content so you can work out how much E85 or gasoline to add.

Which version do I need for an S58 car with FX-350 pumps?

The G80 M3 / G82 M4 kit comes in two versions: one for cars on the OEM high-pressure pumps and one for cars running Spool FX-350 pumps. Choose the one that matches your car, and check other listings for similar version notes.