The new G100UL Avgas

[JCR]

Performance specs discussed at 16 min mark. States fuel detonation characteristics as superior to the old purple 115/145 Avgas. The discussion about ASTM D-910 the is Standard Specification for Leaded Aviation Gasolines.

https://www.youtube.com/watch?v=kB6g9bvumj0

https://www.avweb.com/insider/g100ul-tr ... hard-part/
"G100UL is a blended fuel consisting of a high-octane alkylate base, plus a proprietary additive package. This can be done in a refinery, but is more likely to be splash blended in facilities capable of bringing the refined components together via barge or rail to complete a finished fuel."

I can't find the video but George Braly of GAMI stated that one of the differences from 100LL to G100UL was that Toluene was replaced by Xylene.

[hoffman900]

Boutique gasoline is available for just about any need. It’s easier now to get get great gasoline tailored to your demand than it ever has been. I just don’t see the need to be playing with AvGas anymore.

[prairiehotrodder]

I've been using avgas in my 12.9 CR BBC for the last 5 years. Its around $2 per liter vs $7 for race gas. And it works perfect. My local airport has a cardlock pump where i can just go buy fuel anytime i want.

[jsgarage]

115-145 was designed as a slow burner for giant aircraft cylinder bores and below-2400 rpm engine speeds. We 'borrowed' some for a little 250 Zundapp 2-stroke amateur race motorcycle, at a Navy base one summer evening. Once. At 5000 rpms, the exhaust pipe had a bright 2-foot streamer of still-burning gas trailing behind it. Awfully visible! The Flight Line manager wanted to know what in h... we kids were doing over there.... We learned enough to never try running it on the streets outside the Base, especially at night. Maybe in a 4-stroke it would work right?

[Roundybout]

Depending on which isomer of xylene being used it has a higher octane rating in both RON and MON than toluene. The boiling point is higher than toluene, using too much of it will lower the volatility of the fuel.

I don’t know what effect that has on the fuel when it’s 16,000 feet in the air compared to on the ground. Maybe those additives alter it enough that there’s no issues.

I used to use toluene and xylene as an effective octane booster on small batches of fuel for my off-road toys. Xylene was noticeably not as “crisp” under varying throttle conditions unless at full throttle. I mainly stuck with toluene.