AVGAS/RACE FUEL

People have been fighting the fight for a clean notion that avgas will improve your performance, but at what cost???

Let's break it down and see what avgas really is:

Avgas is the fuel used in areoplanes, but moreimportantly light craft planes, to keep the revs up and keep that baby flying. Simply break down the name AViation GASoline.

Grades

Gasoline used for aviation fuel is generally identified by two numbers associated with its Motor Octane Number(MON). The first number indicates the octane rating of the fuel tested to "aviation lean" standards, which is similar to the an anti-knock index or "pump rating" given to automotive gasoline. The second number indicates the octane rating of the fuel tested to the "aviation rich" standard, which tries to simulate a supercharged condition with a rich mixture, elevated temperatures, and a high manifold pressure. Fuel dyes aid ground crew and pilots in identifying the proper fuel grade:

100LL

Dyed blue, 100LL, spoken as "100 low lead", contains tetra-ethyl lead (TEL), a lead based anti-knock compound, but less than the "highly-leaded" 100/130 avgas it effectively replaced. Most piston aircraft engines require 100LL and a suitable replacement fuel has not yet been developed for these engines. While there are similar engines that burn non-leaded fuels, aircraft are often purchased with engines that use 100LL because many airports only have 100LL. 100LL contains a maximum of 2 grams of lead per US gallon, or maximum 0.56 grams/litre and is the most commonly available and used aviation gasoline.

82UL

82UL is the specification for an unleaded fuel similar to automobile gasoline but without additives. It could potentially be used in aircraft that have a Supplemental Type Certificate for the use of automobile gasoline with an aviation lean octane rating (MON) of 82 or less or an antiknock index of 87 or less. It could not be used in engines that require 100LL. The FAA highly recommends installing placards stating the use of 82UL is or is not approved on those airplanes that specify unleaded autogas (mogas) as an approved fuel.[6] As of 2008, 82UL is not being produced and no refiner has announced plans to put it into production.[7].

80/87

Dyed red, avgas 80/87 had the lowest lead content prior to its phase out in the late 20th century, with a maximum of 0.5 grams lead per U.S. gallon, and was only used in low compression ratio engines.

100/130

Dyed green, avgas 100/130 had a higher octane grade aviation gasoline, containing a maximum of 4 grams of lead per US gallon, maximum 1.12 grams/litre. 100LL "low lead" has replaced avgas 100/130 in most places, but Avgas 100/130 is still sold in Australia, South Africa and New Zealand.

91/96 & 115/145

In the past other grades were also available, particularly for military use, such as avgas 115/145 (dyed purple) and 91/96.

So who should use it?

If your motor has been tuned to handle the high compresion ratio, then use it. So a modified motor with a compresion ratio of 12:1 on an aliminium head, would be ok with using the Avgas sold by some of the dealers in South Africa. Air cooled motors run much hotter while using Avgas. Shelf life is NOT better. The reason pump gas won't last as long is because street gas has extremely lightend hydrocarbons to help your car start and idle. Racing Gasoline does not have these light end hydrocarbons needed for idle and starting, hence the reason race motors start and idle poorly. Also when storing Avgas, don't keep it in a very cold area and avoid placing it on a cement floor as avgas has a tendancy to allow condensation within the drum.Drums breath on a daily basis as the temp rises and falls. As they breath, air enters the drum with a minute amount of moisture. No Bueno. Always sweep the underside of the top of the drum with your finger looking for rust every time you open your drum.

Just be safe when running the avgas and use some lubricant with the petrol to avoid your piston shooting through your block...