At 93 octane, Airworthy meets SI 1070, but exceeds the actual octane requirement
for most low-compression engines that could burn it.
"We're guided by what the car manufacturers say and what the octane requirement
would be, so our responsibility is to fill the need and provide what the consumer would require for their cars to work most efficiently," said Gerald Davis, a spokesman for Sunoco.
Avgas may be unique for its high octane requirement
and thus might actually support a competitive footing with petroleum-based fuel.
Engine designers also learned how to configure combustion chambers for lower octane requirements, that is, how to design mechanical octane numbers into them.
As an example of what could be achieved through combustion-chamber design, Caris and his colleagues catalogued the octane requirements of a wide variety of shapes.
Petersen's STCs, for example, are priced at a reasonable $1.50 to $2 per horsepower, depending on octane requirements
. A few models, such as the PA-28-160, 161 Warriors and the Archers are, at $2750, more expensive.
D910 doesn't specify a minimum amount of TEL; the refiner can use as much or as little as required to hit the octane requirements
. Some get by with less lead--a lot less--because their basic alkalation technology yields higher-octane blend streams.