100 Octane LL AV Gas

[LT1vette]

That is the MOSt informative article with all the facts in one article.

Thx for posting

[turbo69bird]

There’s a few things I don’t agree with in that article . One is it’s not formulated for low RPM that’s relative. Most lycoming engines run at WOT at 2700 ROM or less many 2100 ROMs on the take off roll. So what low RPM he’s taking about and what the High Rpm?

If it doesn’t last longer that’s news to the aviation and landscapers who use it specifically because it doesn’t gel up like regular fuels.
Also airplane engines have 7.0 to 7.9 to one compression in its most popular engines
MOR rating is only half the story as well when it comes to octane .
I’ve personally drained fuel from an airplane wing that sat for over 10 years that didn’t have a tinge of varnish smell or flakes to it.

[L16pilot]

Originally Posted by turbo69bird

There’s a few things I don’t agree with in that article . One is it’s not formulated for low RPM that’s relative. Most lycoming engines run at WOT at 2700 ROM or less many 2100 ROMs on the take off roll. So what low RPM he’s taking about and what the High Rpm?

If it doesn’t last longer that’s news to the aviation and landscapers who use it specifically because it doesn’t gel up like regular fuels.
Also airplane engines have 7.0 to 7.9 to one compression in its most popular engines
MOR rating is only half the story as well when it comes to octane .
I’ve personally drained fuel from an airplane wing that sat for over 10 years that didn’t have a tinge of varnish smell or flakes to it.

Regarding the author's comment about 100LL not being formulated for low RPM, I think what needs to be considered is that when 100LL was created, Tetraethyl lead was the best option to increase the octane rating based on the technology available while meeting all other requirements of recip aviation engines. Your comment about typical GA aircraft engines is correct, (2700 rpm or less), but I think the other performance factors outweighed the operating RPM range during development.

Also, for me personally, Avgas provides other valuable advantages with the prime one being it does not "go bad" in engines/carburetors/fuel systems that sit for extended periods of time saving tons of time/money/effort/frustration. I for one am looking forward to mass distribution and availability of the new GAMI G100UL fuel which promises all the performance/characteristics of 100LL, but without the tetraethyl lead.

[turbo69bird]

Originally Posted by L16pilot

Regarding the author's comment about 100LL not being formulated for low RPM, I think what needs to be considered is that when 100LL was created, Tetraethyl lead was the best option to increase the octane rating based on the technology available while meeting all other requirements of recip aviation engines. Your comment about typical GA aircraft engines is correct, (2700 rpm or less), but I think the other performance factors outweighed the operating RPM range during development.

Also, for me personally, Avgas provides other valuable advantages with the prime one being it does not "go bad" in engines/carburetors/fuel systems that sit for extended periods of time saving tons of time/money/effort/frustration. I for one am looking forward to mass distribution and availability of the new GAMI G100UL fuel which promises all the performance/characteristics of 100LL, but without the tetraethyl lead.

I agree with those point but previous author said that the 100ll didn’t have a longer shelf life.

Idk if I’m thrilled w the new fuel coming online personally promises promises, heard it before we heard that with ethanol being added to fuel it wouldn’t be any differnt then our fuel lines started disintegrating . That’s bad enough in my boat or my car but I don’t like to mess around w any changes in my airplane . It took some time to see the effects of ethanol too it wasn’t right away . I won’t be flying my kids for a while when the new fuel comes out that is all I know .

[turbo69bird]

https://youtu.be/IV3dnLzthDA

Thought this would be a good video for this thread

[L16pilot]

Originally Posted by turbo69bird

I agree with those point but previous author said that the 100ll didn’t have a longer shelf life.

Idk if I’m thrilled w the new fuel coming online personally promises promises, heard it before we heard that with ethanol being added to fuel it wouldn’t be any differnt then our fuel lines started disintegrating . That’s bad enough in my boat or my car but I don’t like to mess around w any changes in my airplane . It took some time to see the effects of ethanol too it wasn’t right away . I won’t be flying my kids for a while when the new fuel comes out that is all I know .

I agree with the shelf life issue as well. As for race gas, I have experience with VP, cannot recall exactly which formula, but it did show signs of going bad in an un-opened 5 gallon can within a couple of years...an experience I've never had with 100LL.

As for the new G100UL, all we have to go by is the extensive testing performed by GAMI which far exceeded the FAA's requirements. True, time will tell, but all indications are positive with no ill effects. Whether we like it or not, 100LL is on the EPA's radar as the single largest source of lead emissions into the atmosphere and once approved unleaded aviation gasoline becomes readily available, the EPA will move quick to ban 100LL.

Also, the video link you posted is excellent...never knew the history behind tetraethyl lead and CFCs....thanks!

[VintageMusclecar]

I've been running 100ll in my Chevelle basically since I got the car back on the road in 2012.



I dyno'ed the 496 in the Chevelle with 100ll and it ran flawlessly.


I've ran 100ll on the dyno numerous other times on other projects, each with 0 issues.


I've A/B/A compared 100ll to 93 Sunoco premium in my Chevelle; on 100ll the car cold starts with minimal fuss and doesn't take much babying when it's cold before it builds enough heat to idle on its own. Idle characteristics are perfect. Hot re-starts are instantaneous. It is worth noting that the currently remaining 1/4 tank of 100ll in the car now is over 3 years old and it still starts and runs fine.



With 93, cold starts require quite a bit of throttle pumping and significant babysitting time when cold before it'll idle on its own. Hot re-starts require holding the throttle open +/- 1/3 and cranking until it starts, and idle quality is noticeably diminished. WOT performance seems to be fine, however.


An aside: combusted 93 octane stinks. 100ll smells fantastic.



Conversely, 93 octane feeding the 358" small block in my wagon is 100% uneventful, the car runs fine on it. Never tried 100ll in the wagon, don't see a need to at this point.


Lastly, I dyno'ed Albert Galdi's 950+ HP supercharged 540 on straight 91 octane fuel from a no-name gas station near the dyno facility. We ran it at 36° timing and +/- 160° water temp with just under 5 lbs. boost, air/fuel ratio was in the high 11's under WOT, and the engine ran perfectly with zero issues. The plugs came out looking absolutely perfect.


In a nutshell; the need for 100ll is somewhat application-specific, but in all the times I've used it in the last +/- 40 years, I've never had a problem with it.


My $.02, FWIW, YMMV.

[COPO]

For those who have purchased Avgas locally, I am assuming this is done at a local municipal airport. Are there any restrictions on the purchase?

I'm assuming it can only go into jerry cans versus directly into the tank of non aircraft. Same sort of restrictions as "off road" or "ag" diesel since there are no road taxes paid.

[JRSully]

I go to a very small local municipal airport here on Long Island. Load up 3 or 4 jugs and leave. It has 2 options
1. typical gas station set up, slide your card, punch in how many gallons or $$ amount you want, pump and leave
2. On occassion, the guy driving the fuel truck will offer it up cheaper than the self serve pump, which is even better

Driving up and pumping directly into a car is no bueno. As stated, no road taxes collected. They let the "fill up your jugs..." situation slide as you "could be bringing fuel to an airplane that is not able to taxi up to the fuel pumps..."
Either way, I love the stuff and glad it is still available.

[WILMASBOYL78]

A few years back I would go to a local airport...park the truck and trailer. Go inside, tell the gal I needed fuel, she opened the gate and I drove down along side the runway to pump. They would fill my sleds direct in the tanks and fill the jugs, too. Pretty cool...

-wilma