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The detail on my estimate of fuel savings by going to 87 octane. I've rounded the numbers to keep the math easier...

I keep close records of our karting (and other spending). Last year, we spent $350 on kart fuel. This was between our two Rotax karts, covering 9 races and many more T&T and coaching sessions. At typical prices, this was about 200L of fuel. As I didn't spend nearly as much time on track as Carson did, I'm going to estimate that he burned 150L and I did 50L.
Our experience when we moved from Briggs to Rotax was that the Rotax karts burned about twice as much as the Briggs motors did, so let's estimate that a heavily-driven Briggs kart would burn 80L per season.

Premium fuel goes for 20 - 25 cents per litre more than regular, so savings on that 80L is about $20/yr.

Feel free to fix any incorrect assumptions I've made. It's been a while since we've been in a Briggs.

I have often said that oil and fuel are still the cheapest part of racing karts. I burn more gas in my generator to keep the A/C going in the rv than I do in the karts. I have no problem buying premium if that's what the club wants. What spare fuel I have after the weekend ends up in the truck or generator anyways and premium is way better for a small engine that sits more than it's used. Don

Since it seems to fit in this thread, I get plenty of questions about the fuel cost between classes and figured I would provide a breakdown.

For ease of use, let's say premium fuel is $1.60/L and mixing oil is $35/L. We will price race fuel at $8.40/L or ~$160 a tin. Based on my experience and lacking recollection, a Briggs uses around 4L of fuel per race day, Rotax around 8L, and Shifter around 10L.

Briggs fuel cost per day - $6.40
Rotax fuel cost per day @50:1 mix ratio - $18.40
Shifter fuel cost per day @25:1 mix ratio - $64.00

What I derive from this is your fuel cost is more dependent on which class you are running compared to which grade of fuel. All of the above costs do pale in comparison to tires, brake pads, and other wear and tear items, I left the VLR out since I do not know what they have decided on fuel spec.

Jack - not to make you feel worse, but if you re-check your math on the shifter, it's actually $98/ day with full race fuel, unless you calculated based on 50% premium mixed with it?

Math is correct, we all run half race fuel and half pump.

I took a sample of the Strathmore 91 octane while filling up my vehicle on June 3, 2024.
When I checked the sample, it came out to about 8 or 10% ethanol for anyone who is interested.

Cheers
Blake

A related suggestion for the shifter drivers in the club.

94 octane fuel is available at the Mobil station in Strathmore. Using this instead of 91 octane would allow you to go from a 50/50 mix to 35/65 race/pump fuel and still hit the same octane in the blended fuel.
MS109 - which I understand is the race fuel being used - contains oxygenates, so a greater % of (ethanol-blended) pump fuel, won’t impact the overall mix.

This would drop the net cost of the fuel blend used for the shifter by >$1/L.

A bit of an update…

As I mentioned previously, there is a significant financial incentive for fuel suppliers to blend ethanol into their gasoline. Additionally, Ontario and Quebec have increased provincial blending requirements that are driving the industry to higher ethanol concentrations.

Blends of up to 15% ethanol are now appearing in some markets in the east. I would expect that migration to the west is not too far off.