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Running Leaded race fuel on direct injection engines

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good day everyone,

Tech talk :)

Ive noticed a lot of the VAG direct injected cars running only unleaded race fuel like VP’s MS109 or Sunoco 260 GT plus. I’ve also know people use ethanol blends like E50-E70.

Any reason why leaded race fuel like a C16/Roo16 not used?

My only guess is that it’s likely the injectors don’t like the chemicals in the leaded race fuel?

I think the problem is probably more the O2 sensor than the injectors.

There is nothing fundamentally stopping you from running a leaded fuel in these engines. Many of them however rely on full time closed loop fuel control via the wideband lambda sensor and as David has pointed out, the sensor life is severely shortened on leaded fuels. Fuels such as E50-E70 also give the same kind of anti knock qualities as some of the leaded race fuels at a fraction of the cost. The only problem with ethanol fuels is that you need to have significantly more fuel flow available which can be a problem on a DI application. Running a higher fuel pressure with an uprated pump and spill valve can build a lot more headroom into the fuel system but on the 2.0 TFSI engine we recently calibrated we were limited to about E30 to provide a safe injector duty cycle.

Thanks David and Andre.

im aware of the shortened life of the O2 sensor when running leaded race fuel, just thought and wondered why no one ran Q16/Roo16 on these DI engines.

What sort of “life expectation” , roughly for the O2 sensor if we ran leaded race fuel? I’ve never heard such info released.

Thanks again

I am always suspicious if the O2 sensors sees more than 50 hours of leaded fuel operation. For dedicated Road Race cars this means we replace O2 sensors at least every season. When lead fouled, the sensors seem to be slower to respond, and often read a bit lean.

I've destroyed a sensor on the dyno using C16 and Q16 race fuel in as little as one tuning session. Granted that wouldn't be the norm but it's certainly possible.