Big news on 100 octane unleaded fuel

griff390

In case anyone didn't read the Piperowner's splash page, here's the update:

"The FAA signed on September 1 supplemental type certificates that allow General Aviation Modifications Inc.’s 100-octane unleaded fuel (G100UL) to be used in every general aviation spark-ignition engine and every airframe powered by those engines."

There has been much confusing and outright false news (no shock) regarding 100 UL for the GA fleet, but it appears to be on its way. Delivery dates and prices are indeterminate.

Here's a couple links to the story from AOPA and AvWeb.

https://www.aopa.org/news-and-media/all-news/2022/september/01/closer-to-an-unleaded-future?utm_source=epilot&utm_medium=email

https://www.avweb.com/ownership/fuel-news/gami-unleaded-avgas-stcs-approved-for-ga-piston-fleet/

jacobsja

Just saw the article. Happy Dance!

Am looking forward to the potential of this:

- No fretting over whether the plugs got fouled in the previous flight.

- The door opening for synthetic oil and a reduction of internal friction.

- The door opening for extended oil drain intervals and not needing to remove the cowling as often.

Oh, yeah, and there is the part of no more lead 🙂

Scott Sherer

Thanks fellows! Great news... Now to find some... With gas already at $8.00/gallon in some cases, it this going to be even more expensive?

empannin

Scott,

I think they were forecasting a premium of < $1 when 100LL was ~$6. I am hoping it becomes popular as a marine fuel as well. The lack of alcohol and high octane would be perfect for marine applications where engines often run at ~ 75% power settings in cruise. The marine market is much larger than aviation and would help with volume pricing. So, not sure - it might be possible to make it for less than 100LL today.

I think the other big deal is 100LL has only a handful of refineries making it in batches and having to clean up hardware afterwards. G100UL could be made with similar equipment but not requiring extensive cleanup between runs.

Hopefully G100UL scales quickly as I don't think anyone will want to hold on to inventory of 100LL.

When 100LL is history we will also have options for better spark plugs as lead fouling will be a thing of the past. I think the biggest impact is going to be full synthetic oils optimized for low friction and high temp durability. This should be a huge help with oil control ring issues, bearings, cams and valve guides. Friction losses can be 10HP+ with current oils - all converted to heat.

Eric

jacobsja

For the marine adoption thought, if we think avgas is on the pricey side, check out pump price when sliding up to a pier. Last I checked, it was nothing more than mogas with insurance premium priced-in. Will see whether the marine folks develop an appetite for unleaded avgas as those engines are perfectly fine with 87 - 91 octane mogas (except for the diesels, of course). If anything, the marine crowd might go for SWIFT UL94. Only realy benefit I see to using unleaded avgas in boating is the lack of water absorbant substances. Ironically, boaters hate water (in the fuel tank).

Am seeing one downside to G100UL: 6.2 - 6.3 pounds per gallon. So the bigger the tanks, the more the useful load reduction. Not a huge loss, but certainly a data point. Fortunately it effects all aircraft requiring 100 octane equally, so no one product line gets to boast a sudden advantage in this metric.

On the up side to the increased per gallon weight is that G100UL is more energy dense than 100LL. By my simplistic and perhaps naive perspective, we should see a slightly lower gph burn and range increase as a result. FAQs on the fuel source appear to back me up on this expectation.

Win some, lose some. Overall seeing this as a big net positive.

Scott, about the price. Yes, it is looking like there is an increase over 100LL. Especially during the initial stages where production capabilities are lower. Expectation is that over time the production cost will come down as more refineries come online and bring in economies of scale. Toward effect on our wallets, call me jaded where I would not really expect to see a price reduction over time, and if anything, holding the price flat-ish as the production costs come down.

Another FAQ item is color. Yellow-ish to Orange. Expect Green if mixed with 100LL. While not specifically mentioned, I'd expect Strawberry Blonde if mixed with Green 100LL (presuming this is still in use in the Bahamas). Yeah, this won't turn into fun 😉

griff390

https://piperowner.org/talk/discussion/comment/1439578#Comment_1439578

Eric;

Exactly. As a nation, we consume between 360 and 390 million gallons of AVgas/yr. That sounds like a lot (and it is), until it's compare to auto fuel. As a nation, we consume that volume in automotive fuel (not counting diesel) every day. Prior to Covid, we consumed the yearly AVgas volume in our vehicles every 9-11 hours.

Compared to automotive fuel, the amount of AVgas produced is so tiny that the refineries would rather not deal with it at all.

I haven't seen the specs yet, but I hope the new 100UL remains paraffin/Alkane based. It will retain the good qualities of having a higher vapor pressure, higher boiling point, and longer storage (Mogas can begin to deteriorate in as little as 3-6 weeks).

griff390

https://piperowner.org/talk/discussion/comment/1439579#Comment_1439579

Jacobsja;

Excellent points.

(insert tongue in cheek) I don't think it's just boaters...I don't know **anyone** who wants water in their fuel. The one exception may be the Bell X-1 which used a 65/35% mixture of alcohol and water for fuel, and LOX as the oxidizer for the rocket engines. I'm going out on a limb here and say most of us don't have an STC to use that in our planes. 🤣😂

Excellent points about the weight difference of the UL fuel. I saw the same data, and quite a while back, Swift UL94 biofuel was reported to be 15% heavier, but as you mentioned, it also contains 15% more energy. In theory, that means we should be able to get the same range per pound of fuel. I generally plan my x-country legs to be somewhere between 2.5 to 3 hours, so I rarely need to top the tanks off anyway.

Resq5hvy

Another market that is going to embrace this new fuel with open arms is auto racing. A number of NA engines run 12:1 up to 16:1 compression.

I have a high compression, 10.5:1, supercharged Chevy LS engine that needs 105 min octane at 7 psi boost and the max octane I can make is 116 and it needs it all at 24 psi boost. The new G100UL having no upper octane number because they can’t find it is music to my ears.

I am also looking forward to synthetic oil. Extended drain, extended TBO’s. My Arrow has 60 hours SMOH, hopefully with the new fuel it can go 5000 hours. Do you realize this new fuel and synthetic oil the engine that is on a new plane my be the only engine that aircraft will ever have.

I am good with a little more for the gas knowing it is going to save me more in the long run with greater engine life.

griff390

https://piperowner.org/talk/discussion/comment/1439583#Comment_1439583

Resq5hvy

Absolutely correct. Racing fuel and AVgas begin with the same base stock from the refinery cracking tower.

Have you tried alcohol injection to help raise the octane number in your supercharged engine?

Scott Sherer

There's a lot of brain power on this thread. Thanks for your thoughts and comments, fellows. Very much appreciated.

Resq5hvy

https://piperowner.org/talk/discussion/comment/1439584#Comment_1439584

Yes, I use methanol/water injection at 500cc per min above 6 psi at 2 psi I use 100cc/min to keep everything cool.

I am thinking of putting water/methanol on my Diesel truck.

empannin

https://piperowner.org/talk/discussion/comment/1439589#Comment_1439589

If you add water/methanol injection I bet it will keep the cylinders clean too!

I am overhauling at 50HP Yanmar marine diesel and it has been fun so far. I bought a mechanical injector tester that raises the pressure to 3000 psi and trips the injectors

Resq5hvy

https://piperowner.org/talk/discussion/comment/1439639#Comment_1439639

My engine is spotless. We borescope it every 30,000 ish when it gets new plugs. Not sure why we must use copper but blown engines like copper plugs.

empannin

A transition to G110UL would also enable closed loop control or at least monitoring with wide band O2 sensors. This would provide more conclusive fuel mixture vs EGT's.

I was partner in an RV-10 and we installed one in the exhaust (6:1). Even with 100LL it kept working fine over 50+ hrs and we made it easy to replace.

Takeoff would be ~ 10:1 (full rich). Climb ~ 12:1 (best power) Cruise 13-15:1 Eco cruise ~ 16:1 (LOP)

If there was a sensor in each exhaust you could use this info to adjust the injectors until you had them matched and then monitor for partial clogs or other issues.

jacobsja

Not to derail too far, but back to the diesels.

Yes WMI will keep the internals clean. Lowers EGTs a good bit as well. Only downsides are that the spray nozzles turn into a maintenance item, and sometimes it takes trial-and-error for finding the correct nozels, water line pressure, and boost psi for triggering the WMI system.

Resq5hvy

https://piperowner.org/talk/discussion/comment/1439651#Comment_1439651

I use Snow Performance, they have it for gas, Diesel and LP, na and boosted applications. Not sure how it will work with Lycoming but they have Chevy LS engines spot on.

My truck is used to pull a heavy trailer over the Rockies, I pull at 2-3 psi boost and spray water/methanol to keep pistons cool and EGT’s down, I have a supercharger so TIT is not an issue. I can adjust when the water sprays and how much with a little box mounted to the firewall. The steam looks to keep my oxygen sensors clean and working as good as new at 275,000 miles.

My water nozzle is after the compressor and before my butterfly. If I get water alcohol pump runaway it will go to the intercooler and slowly evaporate but I have never had pump issues. This way there in no chance of it hydro locking an engine.

My dream setup is an IO 390 with a ProCharger supercharger and Snow Performance water injection on my 73 Arrow II. And a big sticker on my door the says “I put the mental in experimental “. That setup should be good at FL220-FL270, I doubt they will allow me in RVSM Air Space. Just think of the people I could have tell me I am number 1 as I cruise at 180mphias (my plane is so old it is in mph) slowing everyone down….except other PA 28’s. It would give Citation Mustangs something to pass.

I am very large for my maturity level.

This new fuel is going to save us so much money by allowing us to use automotive oil and extended drain intervals. Even if they force us to use aviation oil it will not have lead sludge nor will our plugs be fouled with lead that must be burned off by occasionally running extra lean on long flights or on run up. I have reason to believe engine life/TBO will be extended at least “On Condition” will go on for 1,000’s of hours. This new unleaded fuel is to engines what GPS has been to navigation.

garserio

OPINION:

I am as excited as everybody else regarding a full fleet unleaded fuel. GA needed this a few decades ago and it likely will save GA from the unreasonably fast green energy movement.

However, the manner in which this is being rolled out is ridiculous to me. Utilizing the STC process for the entire fleet, airframe by airframe, is completely inefficient and laden with unnecessary bureaucracy. The FAA decided the fuel is sufficient and safe for the entire fleet. There should be no need for the STC. This just formed a monopoly for GAMI, making a few guys rich and limiting all aircraft owners to only one option. The FAA had a fuel testing and certification program that GAMI decided to work around for efficiency purposes. I understand why they did this, because the FAA was slowing down their innovation. But, now that they innovated and provided data to convince the FAA, there should be a default approval. GAMI should be able to instead license their IP to fuel blenders and get a royalty for each gallon produce until the patent runs out. This will also make them rich, but not on the backs of aircraft owners.

I do not think the STC method of rollout is the right move. It’s foolish, buerecratic and inefficient. These three factors will make roll out slow and frustrating. We need fast and convenient, not slow and complicated.

empannin

Greg,

The FAA spent years with their testing program that ended up going nowhere. The STC process is not perfect but I think they are going to follow the Petersen MOGAS STC process so priced per HP which I think is fair.

George has put his heart and soul into this and I am very thankful for his persistence. Whatever pile of money ends up his way is not going to get back those 10+ years of fighting. He fought the hardest path (FAA) for the smallest market (Aviation). I think if he focused on marine or racing fuel he would have been there years ago.

No doubt the rollout is going to be complicated. I worry 100LL availability will worsen before G100UL ramps. I will happily buy an STC even if it takes awhile for fuel availability in my area.

As I understand it, they will be licensing the tech with AvFuel as the first partner. Although they have paved the way for approval I am not so sure a 2nd fuel will be approved anytime soon as the documentation they did was extensive using custom built test stands and hardware + years of aging data and compatibility tests with a range of common materials in aviation fuel systems

garserio

Eric,

I agree that the FAA's PAFI program flopped and GAMI found a work-around using existing policy to navigate through the bureaucracy. It's an absolute accomplishment in addition to the impressive organic chemistry innovation.

Your rollout worries are my worries as well. The STC process is going to be bogged down now. Paperwork is now going to stall the accomplishments of what one small team did that big oil could not get done under an FAA collaboration program. Will manufacturers also have to be granted STCs on new aircraft and engine builds? Will airports buy loads of G100UL if they don't know who can use the fuel versus who can't? No airport will invest in a separate tank to sell both fuels. When both fuels are being produced, at what point is it no longer financially sustainable to make 100LL in lower volumes? With weak leadership from the FAA, we will simply have chaos until the free market figures it out over time. This will hurt GA.

The FAA should adapt to the reality now... There is an alternative fuel that they just approved for use across the fleet. Simplify the rollout. Get it done. Solve the leaded fuel problem. Approve the fuel universally, enable rapid roll-out and let George earn his royalties. I'm sure that is easier than building a team of STC administrators to facilitate STC sales. He's going to need to setup a call center!

Again, GAMI did what they had to do and I'm sure it was an absolute battle with tons of financial risk and technical complexities. They deserve to be rewarded... and quickly so he can recoup his investment and order his G5.

jacobsja

Ok, so I am a bit lost on the context.

About the STCs, per the AVweb article: "...the FAA has approved supplemental type certificates (STCs) for the use of General Aviation Modifications Inc.’s G100UL 100-octane unleaded avgas in all general aviation piston aircraft." In another article, I saw clarifying langueage for all spark engines.

So from there, it looks like the individual will need to purchase the STC for actually using the fuel. In an analogous manner, any PA-32 owner that has 6 physical seats, but the airframe was allowed 7, needs to get the STC for 'officially' converting their 6 seater into a 6 seater. Fortunately the STC is free in this case.

What am I missing here. We buy the STC, file the 337 and fly. One and done. Is there more bureaucratic machinery to it?

Only potential gotcha I am seeing is for the crowd whom normally uses lower octanes. Now they have to buy the STC anyway to cover the scenario where they happen to need fuel and G100UL is the only blend available.

empannin

Could be a liability issue for the fuel seller for not checking if the plane has the STC? Maybe the STC will also include fuel fill point sticker(s)?

Would be great if the government stepped in and bought a years worth of fuel then distributed it at a discount with the requirement that X% also be passed on to pilots. A large buy would have economy of scale and get over the hump on implementation. I think if fuel was suddenly 3 bucks a gallon you would have more pilots flying too.

I just looked at Oregon is charging Hawaii/Alaska prices for Avgas now (~$7.30 a gallon). Every other state is ~$1 less....

Eric

griff390

Garserio et al;

I had a reply written a few days ago, but didn't send. In that time, all of you have covered the major points I was going to address.

I have some responses and questions.

For years, the stated objective of this FAA program was to develop an unleaded "...drop-in fuel for the entire GA fleet...". If it's truly drop-in, I agree that an STC should be unnecessary. However, as Eric, you and others pointed out, a private entity was able to accomplish what the FAA was unable to do in over 30 years. For that, they deserve their due.

I was also concerned that GAMI would be the sole supplier of fuel, but according to the article, the founders of GAMI have stated that they are open to other companies supplying 100UL “Our arrangement is that any qualified refiner or blender of existing aviation fuels will be eligible to produce and sell it subject to the quality assurance requirements that the FAA has approved,” It appears that GAMI would like to eliminate the possibility a single supplier monopoly, which should promote fair competition and pricing.

I question what will happen to companies like Swift Fuels? What about those engines that can run on Swift's 94UL? My guess is that a separate STC will be required, but if we're lucky, maybe the GAMI STC will hold the door open for them.

I'd still like to know if the new 100UL formulation will be paraffin based like our current 100LL? Paraffin based fuel is higher quality than Mogas. Paraffin based fuels have a higher vapor pressure, higher boiling point which helps prevent vapor lock, a longer shelf life and superior long term storage vs Mogas.

Having Mogas sit in your tanks for more than 6 months is not recommended, and I've even read no more than 3-6 weeks. Mogas will deteriorate, and creates a varnish when it dries. I sincerely hope we're not getting a 100UL Mogas derivative.

The one thing that I have not seen yet is how much this STC will cost. If it's reasonable, it's not a big deal, but if it's high priced, then I'd bet there will be push-back and/or those who will simply fill their tanks with 100UL and fly (illegally) without the STC.

You wrote: "It’s foolish, buerecratic and inefficient."

You were expecting a government agency to NOT be those things? 😅🙄

empannin

Jim,

Good points. I understand the "shelf life" of G100UL is similar to the long shelf life of 100LL (years). I think this is another argument for use as a marine fuel too. In much of the country boating is seasonal. Marine tanks are not easy to drain, fuel stabilizer only goes so far, and alcohol free fuel is not always available.

This can lead to issues like carb overhauls and fuel pump replacements in the spring as well as a blend of sub standard fuel almost the entire season (unless you really run the tank dry). A long life fuel would eliminate these issues and it would start right up.

I have an aircraft tug that I put 100LL in and had not run it in years (at least 3 years). It started right up. If it was pump gas I would likely be cleaning out the carb.

If it is similar to the AutoFuel STC it would be ~ $2 per engine hp. I think this is a fair way to scale it. For my Seneca III this would be $880 (assuming same pricing). Maybe they will offer an intro price for first adopters?

jacobsja

Some questions were either answered by AOPA about a year ago, or strongly hinted at the likely answer (https://www.aopa.org/news-and-media/all-news/2021/october/pilot/alternative-fuels-unleaded):

- "...those planning to use the fuel will need to buy an STC from GAMI that includes new decals for the fuel filler port and a flight manual supplement."

- "...cost of the STC would be similar to that paid for an STC to run mogas in small avgas engine. Petersen Aviation charges about $1.50 per horsepower for its mogas STC."

- "...price will vary more than 100LL because the additives to achieve 100 octane without lead are petroleum-based and thus subject to fluctuations in the price of oil."

Thoughts in order of the quotes:

- Approach seems reasonable enough and consistent with everything else I have seen which 'modifies' the aircraft from its original design.

- If pricing holds true, this is about the cost of ~2/3 fuel capacity for the respective aircraft. Changing the tires and inner-tubes will likely cost more than that. Sure, I get-it that nobody wants to throw away money, and at the same time this money stands to give money back far in excess of its cost.

- Am not an expert in fuel chemistry (nor did I play one on TV), although that description looks like it opens the door for paraffin.

And for the mogas crowd, per FAQs on GAMI's site, it looks like GAMI's STC will cover them as well. Although I cannot tell whether these folks will need to purchase two STCs (one for SWIFT 94UL and one for G100UL). There is enough room for interpretation where mogas burners will need two STCs.

Only real concern I have is that during the initial roll-out of G100UL, pilots easily get the information in terms of what fuel is available at the destination field. Flying to a field with G100UL, but without the STC, might not go so well if there is no self-serve and the delivery truck technician balks at selling without the placard.

Secondary concern is any ramification for a pilot without the STC going to a self-serve pump and buying G100UL. Sure, it is physically possible to get away with it and low risk that anybody will notice. But just the same, a random ramp check can pull the fun out of it.

Resq5hvy

From my understanding the STC will be available on our permanently connected communications device and tracking system. For me it is an iPhone iPad and chips implanted into my brain. The STC paperwork will be on our phones until the sticker arrives. For me 2 for my wings and 1 for my log book.