The Benefits of AVgas

For Paramotoring and Powered Paragliding
by Mo Sheldon, April, 2004

To begin with, the issues of which fuel or oil to use is a very controversial topic with strong opinions and few clear cut answers. I will try to show why I and many motor gurus prefer using AVgas over pump gas.

Essentially our two stroke PPG engines are basically glorified lawn mower engines. And countless lawn mower engines have run just fine with whatever gas and oil is put in them. However, all engines will run better and last longer if you take care of them, including using fresh supplies of quality oil and fuel. Considering the amount of horses we get out of PPG engines, tolerances are more critical and reliability is a very real issue. It makes sense to put the highest quality oil and fuels in your flying machines as a cheap way to increase the reliability and durability of your two stroke engine.

Below are a bunch of differences between pump gas and AVgas: AVgas smells a whole lot better than pump gas (you will appreciate this if you inevitably spill it inside your vehicle or on your hands).

• AVgas is refined to a much higher standard than pump gas.
• AVgas is much cleaner than pump gas.
• AVgas tends to burn smoother than pump gas(probably because it is 100 octane)
• AVgas has some lead in it which is a lubricant (two stroke engines burn hotter and that extra lubrication can mean the difference between a running engine and a seized one. Also, with better heat dissipation, the engine running on AVgas may last a whole lot longer
• AVgas is the same whether you buy it in California, Alaska or Arizona. Pump gas is different from city to city and season to season.
• AVgas has a blue tint to it for easy viewing in a clear tank. Pump gas is a clear translucent.
• AVgas has a MUCH longer shelf life of several months compared to several weeks with pump gas.
• AVgas will not gum up if left for a long periods (The gumming of pump gas is from all the additives gone bad. AVgas has none of these additives)
• AVgas is an excellent cleaner.
• AVgas costs a little more than pump gas
• and lastly for those wanting a good energy boost... AVgas tastes a whole lot better than pump gas.

There are a few myths about AVgas that are simply untrue. The first is that a two stroke motor will run hotter with AVgas. If anything, the opposite is the case. The higher octane of AVgas makes the fuel burn slower and more efficiently. Also the lead in AVgas helps to dissipate heat and acts as a lubricant. Another myth about AVgas is that it will foul the plug and fill the engine with lead deposits. Again, this myth is completely unsubstantiated. I personally have run the same plug using AVgas for over 100 hours, and the plug looks perfect. Also, I have found high hour engines run primarily with AVgas tend to be cleaner on the insides compared to engines run with pump gas.

Considering the small difference in price between pump gas and AVgas, and all the numerous benefits in favor of using AVgas, I strongly recommend using AVgas for all two stroke engines.

Airparamo was founded and is operated by Mo Sheldon (also known as Maurice Sheldon). Mo started with PPG's many moons ago in March of 1998. He has thousands of flights and hundreds of hours flying PPG's. Mo ranked 3rd in 2003 the USPPA national competitions among some of the world's best pilots. Mo earned an Advanced Flight Instructor (AFI) certification in 2003 from Aero Sports Connection (ASC), an organization dedication to promoting ultralights. HE earned a Flight Instructor rating from the USPPA in 2005. In addition, Mo was voted as PPG Wing Director in ASC in 2002 and continues to hold this role. He founded and helped to organize AZPPG, Arizona Powered Paragliding, a local association dedicated to PPG in Arizona.

Here's a bit more from a well known importer of Fresh Breeze Paramotors, Chris Bowles:

The Motor is jetted for Avgas use, with a 160 jet. I don't know what gas you are currently using. The CA pumpgas in NOT very suitable. It only has 92 octane and a very large amount of Alcohol as well as METB additives. The low octane and the hot burning additives have a very negative effect on our high compression 2 stroke engines, these additives are designed for automotive 4 stroke engines to increase combustion temperatures in order to produce lowest emissions. Avgas burns much cooler. What I am trying to say is please don't use Pumpgas if at all possible. If you must, the main jet should be changed up one size.

Also...

I want to renew the recommendation about staying away from ethanol enhanced fuel. The ethanol acts as a solvent, trying to wash off the oil thats in the fuel. This isn't a problem for cars as they have around 60 lbs of oil pressure directly at the bearings and no fuel in the crankcase - our 2cycle engines rely on the oil that is mixed in with the fuel and has to travel around the crank before getting into the cylinder.

The reason I mention this again is a recent rod bearing failure that was possibly caused by 5% ethanol enhanced fuel. Gas stations in most states are required to note the ethanol content on the pump.

That brings me back to the advantages of 100 LL that has a huge, 5 year shelf life, burns cool and doesn't clog up fuel systems when it evaporates. It also doesn't yellow or harden fuel tanks and doesn't smell bad. With premium fuel at around $ 3.00 the 100 LL is not much higher. www.airnav.com has a great section on fuel prices around the country.

I also want to make a plea for using Castrol TTS oil. When we get engines to repair or rebuild I can always tell the ones that have used TTS- they are clean inside, few deposits and rings are not stuck.

By the way MORE oil is not good. 50:1 is fine and if more is used it will actually lean the fuel/air mixture and will make things run hotter and create unburnt oil deposits.

What else? Oh yeah wires. On older motors there can be problems over time where the wires connect to the coil. This has been eliminated and if your Fresh Breeze Simonini doesn't have the silicone wires they are not hard to retrofit. Please contact Southern Skies first if you have a problem, the ppgbiglist isn't the greatest place to get help for specific problems. We can and will be happy to help.

Chris Bowles
www.fresh-breeze.com

Southern Skies, LLC is a full time USHPA and USPPA Certified Paramotoring Shop and School, near Taylorsville, North Carolina in the Brushy Mountains. Southern Skies has been in business since 1994 and has become the United States distributor for German made Fresh Breeze Paramotors and Swing paragliders. They are devoted to the sport of powered paragliding.