Let's have a FUEL thread.
 

State of Alaska has 3 grades of gasoline available.
87 octane is unleaded available everywhere.
In the cities, we have a second choice Premium here in state is 90 Octane ( "Advertised Octane, but questionable )
Most communities have an airfield where one can obtain 100 LowLead Aviation gasoline.
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It has been my practice for high compression motorcycle and Ice racing engines to run a 50/50 blend of 90 Octane pump gasoline and 100 LowLead. Never had any problem with crude high compression carbureted engines.
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Question here regards " spiking my 90 Octane bulk fuel delivery with around 10 % by volume of 100 octane LowLead Avgas.
Possible risk is fouling or destruction of wideband 02 sensors.
Fuel injected piston aircraft seem to function in closed loop with O2 sensors.
How LOW is 100 LOW LEAD ?.
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edit : No Longer a LEAD thread, we are into ADDITIVES now.
Pushing 190 kPa into the gen3 5.3 Liter, Bottom of the 4000 and 4400 rpm columns I have 9 degrees spark, and getting 4 degrees KR. Yes, we are just a tad past the ragged-y edge of 90 octane viability. I have added a full gallon of Berryman's B-12 Chemtool, Great stuff: Contains Toluene, Acetone, MethylEthylKetone, Isopropyl, Methanol, 2-Butoxyethanol- Pretty much all the good stuff, and only $20 per gallon.

.... Question: What easily obtainable volatile solvent should I add to my next fuel delivery for best Octane per Dollar ?
Acetone, Toluene are both available in 5 gallon cans here... Which is better ?
anything else recommended ?

As far as 100 Low Lead, it's a moot point in many of the lower 48 states where catalytic converters are enforced on most cars.
Here in Cali we have 87, 89, and 91 most commonly available. 93 does not exist here.

Low lead avgas is only low lead compared to things like your wheel weights and fishing sinkers.

The " Mootness " is the nature of my question:
Are Fuel injected piston aircraft running in closed loop with Oxygen Sensors surviving on a steady diet of 100 Low Lead Aviation Gasoline ?
IF O2 sensors on pistron aircraft can function with 100 LOW LEAD, than I can use safely as an Octane Enhancer for tuning and or high boost operation.
As I detailed in OP, the best grade of Motor Gasoline available on the road system here is rated 90 Octane, and that is questionable, as it shares hoses and fuel delivery compartments on delivery trucks that also move much greater quantities of 87 octane. We also get anomolous seasonal refinery formula changeover(s) that will give LOYS of knock retard.
As well, many remote fuel stations in this state and Canada only have 87 octane on tap.
One can try to drive gently, but a viable option is to carry a couple 5 gallon cans of 100 LowLead, or a can of Toluene for emergency use. Either product will keep indefinitely if stored in a well seeled STEEL container.
................. Again, the original QUESTION is: Will 100 LL AvGas foul an O2 sensor ?
I have had no problem with long term use at 5% concentration, but curious how it works on piston aircraft .

There's a ton of lead in 100LL. It will crap up WB02's for sure. I use to get it for free and ran it for years and years when I worked in aviation. My old 87 turbo supra loved the stuff.

Cruise by small general aviation airport shops and ask. A lot of times you get it for free. They can’t legally put it back in a plane after its drained without a permit. So most shops have tanks of the stuff they have to pay to get rid of as hazardous waste. We gave away tons of it to airboat guys.

50/50 ethanol/methanol blends will go a long way. Even 30% blends are better than 91/93.

Toluene/xylene blends can be semi cost effective as well if you buy drums of the stuff.

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How much Lead per Ton ?
Is it a fact that modern fuel injected aircraft piston engines run in closed loop mode with Oxygen Sensors ?
How much 100 Low Lead can I blend with Unleaded pump gas and safely not destroy my Wideband sensor ?
As I say, I have been adding 2 to 5% AvGas to my bulk fuel deliveries since 2016 without issue.

It is not a fact that modern fuel injected aircraft engines run O2 sensors. They run open loop because of "100LL" gas.
Low lead is a misnomer as it has less lead than "normal" avgas, but still a ton of it, still too much for most O2 sensors.

Half my day was pulling plugs on all the general aviation flight school planes and cleaning the carbon that would bridge the gap on the plugs. It's bad. Google says about 2g per gallon.

Also thought this was interesting. I never knew that leaded gasoline was basically deadliest product in the history of the planet.

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Berryman's B-12 Chemtool injection cleaner is only $20 per gallon can.
%85 Acetone
%10 Toluene
A bit of MethylEthyl Ketone, 2-Butoxyethanol, Isopropyl.
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My math indicates B-12@ 130 Octane x 1 gallon = 130
90 Octane x 19 gallon = 1710
..........19 to one mix..........20 gallon blend = 1840/20= 92 octane

Where/when is the point of diminishing returns power wise? Is the timing way advanced to take advantage of the “extra” octane?

. Advance ? No sir, we are going deep into RETARD territory here:

4000 and 4400 rpm columns bottom out at 9 degrees spark advance, and I am getting 4 degrees Knock Retard.
I am riding just a bit OVER the ragged edge of 90 Octane safe zone.

Leaded fuel might be some toxic stuff but without it, we might all be speaking the German language now. That 130 octane AVGAS back in WW II allowed our fighter aircraft to outclimb and overtake the best German and Japanese piston engine aircraft ever made. That fuel was pure joy to those extremely high performance American and British Packard and Rolls Royce Merlin V12 and Allison motors in the P-51, P-38 and the Spitfire. The Wright R-1820 Cyclone engines in the B-17 and the Pratt R-4360 in the -29 bomber all had quite a thirst for this type of fuel.

Rick

What is the “ideal” octane rating for your setup?

Good question.
IF there was 93 octane pump within a thousand miles I would be running THAT.
Best obtainable Unleaded in this state is 90 Octane. I have tuned for, and run 11 PSI manifold pressure on a supercharged 4.8 for 8 years without any problem nor parts breakage. In my limited experience, 90 Octane, 11 PSI and 11 degrees spark "Love you Long time".
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New project is a gen3 5.3 208/214 TSP Low Lift cam, 13 PSI and Spark advance at 9 degrees MINUS 4 degrees KR - I'd say motor WOULD like more Octane, if I could get it.
I just turned up the BE fuel in the 3600 to 4400 rpm range by 11%-- When in doubt POUR MOAR gasoline on the fire.
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I think the better solution would be 50/50 windshield washer fluid from a progressive controller and a 5 GALLON tank.

Shame you don't have ethanol up your way, sounds like exactly what you need.

Most of the year his car would likely not even crank on ethanol. Alaska temperatures are no joke.

It would if he blended it. I would order a drum of C85 and mix it 50/50 with 87 octane. That should get the ethanol content around 50%, Set the stoich table for E50 in the tune, and he will be able to run all the timing. It will still start fine in the cold...hence why gas stations with E85 normally dial the E content back to around 60-65% in the winter months. E50 blended with 87 octane pump gas still comes in around 99-100 octane.

I can second that. Not that I have alaska temps here. But it gets pretty cold. At -10* my car cranked right up with e50ish blend. Not that I'd really be out driving around a hot rod when its that cold though. I liked to run ethanol free 91 and mix in e85 to about 50-60% on the Content sensor. Worked really well. No intercooler and I ran 19lbs without issue on a little twin gt35 5.3 setup.