av gas?

[rod]

any one know exactly what octane av gas is when related to race engines. I know airplane octane is or at least used to be different.
also has the lead content been lowered like they said it was going to be?
thanks Rod in AZ

[SS3860]

Av gas is rated 100LL low lead. That's low lead in the aviation community. It is comparable to 110 race gas. Used it for years in 13/1 bracket motors without any issues.

[Project 392]

As I understand it, 100LL replaced 100-115 av gas that was used for years. I think there used to be a 115-130 rating way back when also. That's the old lean-rich ratings. I too had used it for years in a 12.8-1 motor.

Victor in Kingman/Mesa

[Steve Stasko]

I've been running it in my bracket car for the last 6-7 years. No difference in ET for me between 100LL, 110 VP or 110 Sunoco. 528" Chrysler, 13.2:1 with aluminum heads. Just bought 15 gallons Friday night, $6.75/gal. 15 gallons cost me the same as 1 5-gallon pail of VP or Sunoco.

[Jeff Niceswanger]

What's the RM rating for av gas? Is the rating your seeing Research Octane?
Research Octane Number (RON) The RON test measures a fuel's anti-knock performance under relatively mild engine conditions, such as those experienced during low-speed driving and acceleration. Test conditions: The fuel is tested in a variable compression ratio engine at a low engine speed of 600 rpm.Significance: RON is the most common octane rating used around the world, particularly in Europe, Australia, and many other countries. Motor Octane Number (MON) The MON test measures a fuel's resistance to knocking under more severe, high-load engine conditions, such as high speed or highway driving. Test conditions: The fuel is tested in the same engine used for the RON test but under harsher conditions, including a higher engine speed of 900 rpm and a preheated fuel mixture. Significance: The MON is typically 8 to 12 points lower than the RON for the same gasoline because the test conditions are more demanding. The \((R+M)/2\) Index For gasoline sold in the United States and Canada, the advertised octane rating is the average of the RON and MON values. Calculation: AKI = \((RON+MON)/2\).Example: A fuel with a RON of 91 and a MON of 83 would have an AKI of 87, which is what's displayed on the pump. International comparison: As a result of this averaging, the same fuel will have a lower octane number on a North American pump than in countries that use the RON standard. For example, 87 AKI fuel in the U.S. is equivalent to 91 RON fuel in other parts of the world.

I noticed the Turbo Blue at a local gas station pump is 100 octane. Its 105 Research and 96 Motor Octane. (Just look at the yellow R+M sticker on the pump face).
100 plus 96 = 201 divided by 2 = 100.5. So, its advertised to us racers at 105 but if tested by street gas ratings is only 100.
In the early 1970s, the Sunoco 260 premium fuel had an octane rating of 97.5. It was sold at "Custom-Blended" pumps, which allowed customers to choose from a range of octane levels. It was rated with the higher "Research" octane as the RM/2 method had not been implemented back then. Based on the difference between 1970s and modern octane rating methods, the 1970s version of Sunoco 260, which had a Research Octane Number (RON) of 97.5, would have likely been rated between 93 and 95 using the modern (R+M)/2 method.

[Mike Taylor 3601]

Just spend a little more for GOOD race fuel and save yourself ALOT later.
don't buy your race fuel from a pump or bulk tank that is vented...
buy it and store it...in a sealed drum or sealed metal can..
run your carb or efi. dry and pump fuel from cell and store it in metal can, between race weekends, even if racing the next weekend.
these things will protect you from ALOT of problems..

[Jeff Niceswanger]

Originally Posted by Mike Taylor 3601

Just spend a little more for GOOD race fuel and save yourself ALOT later.
don't buy your race fuel from a pump or bulk tank that is vented...
buy it and store it...in a sealed drum or sealed metal can..
run your carb or efi. dry and pump fuel from cell and store it in metal can, between race weekends, even if racing the next weekend.
these things will protect you from ALOT of problems..

Hi Mike. In 25 years of racing the SS'er I only failed with C-11. Once we had to take an entire drum back. Hot, muggy, hi humidity tracks was a problem for us and C-11 plenty of times. We never took the fuel out of the car after races, and it had a plastic Jazz cell. Maybe if we took the C-11 out and stored it in steel cans it would have helped. But C-12 never failed along with C-25, all the Sunoco fuels, even while leaving them in the plastic cell for extended timeframes. We did of course take the ERC out. Even after swapping ERC with anything else, our house smelled like ERC until the underneath was wiped down. That stuff STUNK>>>>

[bpete]

What is the DC ( dielectric constant ) spec value for 100LL ?
Anyone on here ever tested 100LL ?


Brad

[Dan Bennett]

Not an issue for race cars, but if you have a street driven musclecar I found a problem.

With high c.r. like LS6 and L78 and even a Stage 1, it would always blow a baffle loose in a stock muffler. At the time we had a small municipal airport and no one cared if I pulled up to the pump for LL100.

Later I read info that the problem was caused by the LL100 being too "hot" or too "dry" and therefore caused the problem, but not enough detail was given for me to understand what that meant.

[Jeff Stout]

I believe Falcon field in Mesa Az still carries the green 130. The collection of antique planes made it necessary to have on hand.