I read that drag racers from years ago used diesel as an octane booster. I did a test with an 80 to one mix with regular car gas and felt a small boost. sorry no charts with this method.

Above from Power Nation advertising Race Gas fuel concentrate. Similar to Boostane?? Use your own best judgement.

I am still thinking about options.

Fill it on land or buy 5 gallons of race gas good luck!

You "felt" a small boost?
Do tell!
About a point or a couple tenths of octane?

interesting that you asked, here is the info. I did the test in my rv6 airplane. it runs an 180 hp lycoming engine. on take off there is a noticeable difference of power on a 90 degree day and a 50 degree day. I decided to add a quart of diesel to 20 gallons of regular gas and took off on a 90 degree day. the result was that if felt like the usual power of a cold day. those old time drag racers knew a thing or two.

Diesel fuel has an octane rating of 25-40. Mixing 2% diesel fuel into gasoline will lower the overall octane rating by 1 point. Getting 10% diesel contamination lowers octane by 5 points, which is enough to create problems in most engines.

That’s what I thought too.

Perhaps the diesel created a change in the mixture and that’s where the extra “power” came from?

I just don’t see diesel being beneficial.

Not to step into the whirlwind of expertise contained here, but I just watched Engine Masters Sunday, and they did a myth-busting episode on Octane. Now to avoid boost and turbo and other variables blah blah, they had a 540hp LS3 NA engine on the dyno. They tested 87 and 91 pump, 110 and 116 Sunoco, and E85. For each grade, they completely drained the engine between each run, did 'calibration' runs for each octane, (timing, AFR, etc) before hitting it for the official run.

(Surprised me!)

Oddly, the engine liked 29-degree timing for max power on all fuels. Cranking timing up and down didn't help power. For each to make max horsepower, they fiddled with the AFRs. In the end, the best run from 87 octane to 116 octane, the engine horsepower/torque difference between them all was just 1-3 points. (91 pump did the best of gas, but E85 topped them all by a smidge)

Their conclusion was timing for max power is about what the build of the engine wants, not the octane. In a controlled environment, 87 was as good a anything else, but all noted they would not run it on the street with a good motor because of extended load, underhood heat, etc.. Octane level was only a matter of where the engine detonated, if it detonated, not horsepower, and the old myth of raising the octane and cranking in timing to get more horsepower was totally unfounded. Use of 110 and 116 was a waste on a NA street rod as they couldn't make is make more power out of it with anything they did. The E85--made the most torque and horsepower, but they had to crank what would be 'gas' AFR to around 8.5, burning more fuel compared to gas. They noted under boost, E85 made significant gains over gas-based fuels because of its cool charge and high oxygen content.

It shed some light on a lot of my old beliefs and theories. I like octane, so don't kill the messenger, but I feel a little better knowing if I'm on fumes and have to splash in a little 87 octane dock gas to get home, it's not the end of the world.

Pretty cool episode! I love those guys!