Why not Avgas in your car?

By Sunoco Fuels
Sep 13, 2024 |Sunoco, Sponsored Content,

gasoline, Fuel Facts, Avgas | Posted in Features | From the Sept. 2020 issue | Never miss an article

This isn’t a new idea: Why not run aviation fuel in your classic? Thanks to its high octane and lack of ethanol, this avgas sounds intriguing.

High Octane:

Pump fuel intended for cars and trucks is rated on the Anti-Knock Index, which is the average between the Research Octane Number and the Motor Octane Number. Avgas, however, is rated on a slightly different scale. As a result, the avgas 100 found at many regional airports would have about as much knock resistance as a 105-octane fuel intended for cars and truck

Highly Refined:

Zachary J. Santner, technical specialist at Sunoco Race Fuels, notes that avgas can be more refined and consistent than the fuel found at the corner store. Vapor pressure for avgas, he explains, often falls between just 5.5 and 7.1 psi; depending on the season and location, typical pump fuel for passenger cars can range from 5 to 15 psi. However, Santner adds that his company’s race products never deviate, always following the same formula.

Zero Ethanol:

Avgas doesn’t contain any ethanol. While ethanol can help gasoline make more power, it can also cause hardware issues in older vehicles. “Can’t pull your plane over on the side of the road if there’s a problem with the fuel system,” Santner notes.

Some Lead:

Not only does lead cause smog, but it’s not compatible with the oxygen sensors and other pieces of emissions equipment found in most cars built since the ’70s. Even avgas 100LL, a newer, low-lead option, still contains lead–about 1.9 grams per gallon.

Legality and Logistics:

Avgas isn’t taxed for road use, and cars might not be welcome on the taxiways at the local airport.

Unnecessary Additives:

Avgas contains some of the same additives found in pump fuel, including corrosion inhibitors and antioxidants that increase shelf life. However, some of its additives aren’t found in car fuels–like compounds that prevent icing and static electricity. “It’s just more additives that you don’t need,” Santner notes. “Car gas has additives designed for cars, and airplane gas has additives designed for airplanes.”

More Fuel Facts from Classic Motorsports:

• What is race gas?
• Which race fuel is right for you?
• Buying and storing race fuel
• The right fuel in the fall might help your engine start in the spring
• Fuels for storage: good, better, best
• How much octane is enough for my classic?
• 93-octane not enough? Solutions exist.
• Can you blend fuels to get the right mix?
• Tuning for today's oxygenated fuels
• Picking the proper gas
• How to choose a quality gas station
• Why is there ethanol in our gasoline?
• Understanding additives
• Why not avgas in your car?
• Water is great for your plants, not so much for your fuel system
• Gasoline makes a terrific degreaser, yet this practice can kill you
• Are high-octane fuels more stable?
• Ideal fuels for wintertime storage
• What ever happened to leaded gasoline?
• Homebrewed, non-ethanol fuel: A potentially deadly DIY
• Was yesterday's gasoline better?
• Cars that sit need clean fuel, too
• Is all that alcohol good or bad?
​​​​​​​• Does the octane number in your manual match the one on the pump?
• What's the right fuel for forced-induction cars?
​​​​​​​• What's in aftermarket additives anyway?
​​​​​​​• The perils of running rich​​​​​​​
• Should you fill up your classic before parking for the winter?
• Do all gas stations offer the same quality of fuel?
• How to know if you are using the correct fuel
• How to keep carbon deposits out of your engine
• Does Ethanol actually corrode metals and plastics?
• The valuable benefits of running a race fuel
• Flex fuel: Should you reach for that nozzle? ​​​​​​​