I may be borderline to get away with 93 E10 now. For those who are running pump fuel plus a mix of race fuel, what's your choice of fuel and what ratio do you need for your combination?

FWIW, I'm ASSuming that current octane boosters are either ineffective or so MMT-heavy that plugs and O2 sensors get a heavy coating of "orange death" when used. I've run some of them in the past when absolutely necessary, but would prefer a different solution this time. Thx

I have a friend who mixes E85 into regular pump to boost the octane a little. I don't know the ratios but he doesn't use any ethanol specific parts or or a special carb so it can't be a whole lot.

My 410 inch small block is 9 1/2 to 1 compression , I run BP Super ( it checked with a higher specific gravity , I don't check every time I purchase gas but do on occasion ) and a splash of Sunoco 110 mixed in not much maybe a few quarts .

nitrous oxide is a great additive, usually cleans the plugs nice too

Mine is slightly over 11-1 and if I put timing where it really wants it. I have to mic 91 with 110-110 to run

Where I have timing now I can get away with straight 91 - 93 Usually its ok. Real hot days it will ping slightly on accel

One of my cars likes a bit more than 91; I've mixed 100LL Avgas and 110 VP or Renegade, and it's happy either way.
Approx 25% added in my case on this car.

I mix 50/50, super unleaded and 100LL Avgas. No issues 12.5:1 c/r.

Switch to pump E 85 if you can and don't worry about fuel again

You should be able to get a street legal 100 octane unleaded fuel from VP or Sunoco or Torco. That is what I'd use in a street car. It is expensive but it blends nicely with pump gas and it works.
The other option is av gas if you can buy it in your area. Av gas is usually a better solution for rural areas than urban areas. A little bit of av gas will boost the octane level of pump gas. Av gas works pretty well with carbs but it has too much lead for EFI systems. The extra lead in av gas can be a plus for older engines that don't have hard seats, but it isn't good for new engines.

E85 is not readily available enough in my area to be the dedicated fuel for a "drive anywhere' street car

There's a local Sunoco race fuel dealer (maybe 10 miles from home) that typically has the UL 100, along w/ most of the rest of their fuel lineup. Last time I checked it was close to $100 for a 5-gal pail, and the price difference between that and something like 112 leaded wasn't much either.

Just playing "What if...?", I ran the numbers for both of those fuels targeting a 95-96 octane blend and the 112 leaded would go about twice as far. Not sure I want to go that direction, yet.

I'd use the 112 in your old car since it has a carb, no cats and no wideband sensor. In a new car with EFI, cats and wideband sensors I'd use the unleaded 100.

Hmm... a few years ago I bought a wideband from a guy who used to live in Wilsonville OR that I was still planning on trying out, so maybe I should stick to the unleaded options

I live in Canada so my experience may not help but I have been running a blend for the last 4 seasons. I mix 15 liters of Esso/Exxon 91 with 5 liters of Fury 112..

My engine is a 11.9 to one 451 - 400 based big block. 3100 lb car with a powerglide. It pumps right at 160 and up till this point I have had no issues. I am planning on pulling it out this winter to look at it. The car has run a best of 6.28 in the 1/8 and 9,89 in the 1/4. I just counted the runs and it is 560 runs on it since I built it. I run 36 Degrees timing.

I basically add the race fuel to give the top end a little lube, add to my piece of mind and lastly i think it may help a little with consistency.

However my favorite part of it is the reduced cost. I figure I save enough in fuel on a weekend racing that one of the days entry fees are covered.

i will report back once I have had a look in side to confirm the health of the motor.

How do you determine if the fuels you are using are indeed 'blendable", as I have read some race blends do not have that quality.
Is simply mixing them in a clear container and observing adequate?

If I had any questions on fuel compatibility, I'd call the race fuel company and ask directly.

For what I've done over the years -- meaning nothing "tricky" -- it's been very straight forward.

We ran a mixture of 1:4, 1:3 and 2:3 pump gas 93 to Sunoco 110 for over 15 years. Really didn't need it due to our compression (10-11:1 on various combos) , but more because of the extra ethanol in the pump gas was creating some issues. I have since changed our fuel systems to return styles vs dead head systems and have been able to run straight pump gas successfully now.

My confidence in how fresh pump premium actually is, is zero. I'm in a small town and I bet it takes 6 months for them to call for a load of Premium. It's for sure gone stale in that time span.

Stale 94 is no better than high turnover fresh 87 and that's my real-world experience. Something to think about if you do select Premium, is you have to pump 2 gallons of the last Person's 87 before you are actually getting 94 out the nozzle.

I use 87 and mix it minimum 20% to 100LL. The cars like 30% better for all out performance, but 20% is good enough for cruising . Cast iron J heads, 10.5:1 340's.

My 11:1 750 Sport Bike is down to 10% of 100LL but I've ruined one Lambda sensor on it. As above, I don't even bother putting Premium in it on a road trip.

Run as little as you can get away with for your purpose. Over-mixing is a waste of money and no performance gain which I found out instantly with the Bike (Fuel Injected/Computer control) and later on the Cars.

Starting last year, I mix my fuel and let it set for a few days before using it. The Chemistry nerd in me says the fuel needs time to be fully homogeneous and it does make a difference in how the car runs.