Swift 100R is now ASTM

[Ibra]

54 minutes ago, Ryan ORL said:

From what I've read about it thus far, its MON is lower than 100LL and G100UL (neither of which are actually 100 in reality, but higher), which would significantly reduce detonation margins in my engine (IO-360-A3B6) for example

I don't think Swift will struggle with 100R in IO360-A3B6? we will know soon for sure.

I recall at Oshkosh this year, they mentioned 1000 engines being tested for 100R. However, they admitted challenges for Conti 550 and Lyco 540, for these engine, G100UL is probably the only choice for now...

Recently, Lycoming has proved that TIO540-J can run on 96 MON octane with adjusted pressure-timing, so even Swift 100R fuel can get their way into these, here is the fun part, these engine may need to use GAMI PRISM or TCM PowerLink, these need to be certified, things could be heading that way as well, if the price of these magnetos is right...

 

 

Edited Friday at 09:22 PM by Ibra

[Joshua Blackh4t]

If Gami fuel is better for the engine, but harder on the tanks and paint, I think I'd wear that risk. Maybe use better paint around the filler area? It could be a feature, especially not an issue on high wings. 

If the cost of continuing to fly our planes is new fuel lines, maybe a tank reseal and some industrial paint around the filler, well, then so be it. Better than the alternative. 

[toto]

I went around looking for some first-hand experiences with 100R. 

This thread has some mildly interesting feedback, including the apparent fact that the Swift fuel uses no aromatics (which I guess is the source of most of the materials incompatibility issues with G100UL).

https://old.reddit.com/r/flying/comments/1h3zdfy/100r_smells_weird/

At this point, “different from G100UL” seems like a key measure of success. Both for certification and formulation.  

[Will.iam]

I thought I remember in one of gami's engine test, that no detonation happens until CHT gets above 420 degrees even if you run the engine right at the worst possible red box area but the rate at which the CHT's are rising is fastest there.  Seems to me if we now have good CHT monitors, and most consider 400 degrees the upper limit, that if 100R did not have as much detonation margin, you would see it on take off if you had a cht rising above 400. question would be if reducing power would be acceptable enough to still make the climb out profile?

[0TreeLemur]

9 hours ago, Will.iam said:

question would be if reducing power would be acceptable enough to still make the climb out profile?

That is an excellent question.   If yes, then the question becomes are you willing to live with a reduced margin of safety on CHT that prevents your engine from self destructing?

[Rick Junkin]

15 minutes ago, 0TreeLemur said:

That is an excellent question.   If yes, then the question becomes are you willing to live with a reduced margin of safety on CHT that prevents your engine from 

Is a demonstrated full power detonation margin a requirement for approval of a fuel for use in a given engine/aircraft? In other words, is it even possible that reducing power would be an option available to us?

I don’t know anything about how this approval process works, either by STC or ASTM. Someone much smarter than me please weigh in. Could a fuel be approved and available for use in a given engine if that fuel/engine combination wasn’t able to demonstrate some nominal full power detonation margin?

[gabez]

On 9/5/2025 at 2:58 PM, Joshua Blackh4t said:

If Gami fuel is better for the engine, but harder on the tanks and paint, I think I'd wear that risk. Maybe use better paint around the filler area? It could be a feature, especially not an issue on high wings. 

If the cost of continuing to fly our planes is new fuel lines, maybe a tank reseal and some industrial paint around the filler, well, then so be it. Better than the alternative. 

unfortunately you do not know what needs to be done to your plane to be fully compatible with G100UL. Braly won'd disclose the log books from his Cirrus. Every plane that uses G100UL is a guinea plug. It's not just lines and paint. 

[1980Mooney]

11 hours ago, gabez said:

unfortunately you do not know what needs to be done to your plane to be fully compatible with G100UL. Braly won'd disclose the log books from his Cirrus. Every plane that uses G100UL is a guinea plug. It's not just lines and paint. 

Every plane that uses Swift fuel is a guinea pig.

Swift 94UL met ASTM D7547.  Yet prolonged use by UND caused documented engine damage.  UND Report Details Valve Issues Experienced With Swift Fuels 94UL - AVweb

And Swift already admits that there are issues with 100R in high performance engines - big 6's and turbocharged.  

[1980Mooney]

13 hours ago, Rick Junkin said:

Is a demonstrated full power detonation margin a requirement for approval of a fuel for use in a given engine/aircraft? In other words, is it even possible that reducing power would be an option available to us?

I don’t know anything about how this approval process works, either by STC or ASTM. Someone much smarter than me please weigh in. Could a fuel be approved and available for use in a given engine if that fuel/engine combination wasn’t able to demonstrate some nominal full power detonation margin?

I don't see how that could work.  That solution means a pilot would need to reduce power just when he likely needs full power.  For those of us back in the 60's and early 70's that used to experiment with distributor timing finding maximum spark advance on our manual transmission cars, when we heard it knocking, we could just let off the throttle or maybe downshift before going into full blown detonation.   We could just pull over and stop - maybe fiddle with the timing advance some more.

 But with our plane, there are many times we need full power - take off, clearing an obstacle.  That means the POH would need two (2) sets of performance charts/sections for Full Power and Reduced (Knocking/Detonation) Power.  Putting a pilot in the position of trying to decide whether to destroy the engine vs attain a needed rate of climb seems like a formula for disaster.  I bet the lawyers for everyone (airframe, engine and even the fuel suppliers) would stop it in its tracks.

More likely they would mandate permanent engine modifications such as reduced compression (piston change), reduced timing, reduced max RPM, limited/reduced max boost

[gabez]

3 hours ago, 1980Mooney said:

Every plane that uses Swift fuel is a guinea pig.

Swift 94UL met ASTM D7547.  Yet prolonged use by UND caused documented engine damage.  UND Report Details Valve Issues Experienced With Swift Fuels 94UL - AVweb

And Swift already admits that there are issues with 100R in high performance engines - big 6's and turbocharged.  

I appreciate that. I don't mind knowing there are issues with certain engines, I do mind when GAMI comes out saying it is drop in and then 25+ planes got bricked and one was totaled $600K 421C. 

They now have changed their narrative: as there is no perfect fuel, they have added a disclaimer on wet tanks when you buy the STC and changed the FAQ. in November when I (and many others) got the STC it was drop in, don't need to change a thing. and that's a fact. 

[Ibra]

13 hours ago, 1980Mooney said:

I don't see how that could work.  That solution means a pilot would need to reduce power just when he likely needs full power.

The problem with UND was not "full power (rich climb)", it was their "leaning technique (cruise)".

In UND, they were running Archers at 70%-80% power on peak EGT with CTH > 450F as "normal business", I get that Lycoming engines are certified by FAA to cope with continuous max power and max CHT = 500F on 100LL, however, only a monkey flies like that (most of us tend to babysit the engine).

I have operate the Archer that UND flew, albeit on less hours (450h over 5 years), I flew it using SP98 (87 Octane) on Mogas STC, takeoff were never a problem and I never let CHT > 390F in climbs or cruise:

* Patterson STC, prohibited peak EGT operation on Mogas EN228.

* Lycoming advise against peak EGT operations at 75% on Avgas 100LL.

Basically, they were "red-boxing" even with 100LL, it's not advisable and it's false fuel economy. Most schools tend to have various SOP to keep CHT under 400F, use 55%-65% power? keep full rich? 

I think on gently engine management, I am sure one can make sacrifices but for airframe, fuel tanks, paint...there is not much one can do...

If 100R is fine for airframe, I am fine using it even with bunch of placards on leaning or CHT 

Edited Monday at 05:43 AM by Ibra

[Ibra]

On 9/6/2025 at 6:18 PM, Will.iam said:

I thought I remember in one of gami's engine test, that no detonation happens until CHT gets above 420 degrees even if you run the engine right at the worst possible red box area but the rate at which the CHT's are rising is fastest there.  Seems to me if we now have good CHT monitors, and most consider 400 degrees the upper limit, that if 100R did not have as much detonation margin, you would see it on take off if you had a cht rising above 400. question would be if reducing power would be acceptable enough to still make the climb out profile?

I am sure most of us don't exceed CHT > 420F on takeoff? in M20J, you need to climb at VX with cowl flap closed to 2000ft with OAT at 100F, assuming one is full rich (they need to be at least 250F - 350F Rich of Peak to keep out of "red-box").

Most of us already accept lower climb gradients as we tend to "baby sit" engines under 390F on climb by using more speed or more fuel to keep out of red-box, same when we lean LOP under 65% power, it's not optimal but that's how one keep their engines running for a long time.

I don't feel that I compromise any safety for keeping CHT < 400F even while using 100LL: I can still fly where I want with no apparent limitations, well I use full rich for takeoff (unless high density), I  climb at Vy to cool my engine and I tend to LOP under 65% power. I would do the same with 100R, 

Of course there are pilots who can melt an IO360 by aggressive leaning toward peak EGT at 100%-75% power, having 100LL or 100R, won't change anything for such pilot...

Edited Sunday at 08:09 PM by Ibra

[McMooney]

at some point, lycoming or mooney tested 96 octane fuel,  in my lycoming io-360-a1a and found it acceptable, so pfft don't care at all about some 1000hp engine not being able to use it. 

 where is this blurb 100r may not work in some applications?  heck i live in houston if have to reduce takeoff to 1000 fpm to prevent detonation, not seeing an issue,  anyone living higher than sea level probably wouldn't have to do anything

[1980Mooney]

2 hours ago, gabez said:

I appreciate that. I don't mind knowing there are issues with certain engines, I do mind when GAMI comes out saying it is drop in and then 25+ planes got bricked and one was totaled $600K 421C. 

They now have changed their narrative: as there is no perfect fuel, they have added a disclaimer on wet tanks when you buy the STC and changed the FAQ. in November when I (and many others) got the STC it was drop in, don't need to change a thing. and that's a fact. 

Swift said 94UL was an ASTM approved "drop-in" fuel.  Except it wasn't in the real world.  Now they say 100R is an ASTM approved "drop in" fuel.  Except it may not work in 25% of the fleet.....  "and that's a fact".

"The remaining 25% are more complicated. About 60% of that slice of the pie chart are what he calls “the 550s,” six-cylinder engines in singles and light twins that fill the gap between the engines that are quite happy on 94 UL and the ultra-high-performance boosted sixes that will be the toughest to fuel with unleaded. Testing will begin later this year on a Continental 550 and d’Acosta said it will take about 18 months."

What good is ASTM if they don't even know if it will work reliably in the Continental and big Lycoming engines? - I mean Seriously?

Edited Sunday at 08:45 PM by 1980Mooney

[gabez]

2 hours ago, 1980Mooney said:

Swift said 94UL was an ASTM approved "drop-in" fuel.  Except it wasn't in the real world.  Now they say 100R is an ASTM approved "drop in" fuel.  Except it may not work in 25% of the fleet.....  "and that's a fact".

"The remaining 25% are more complicated. About 60% of that slice of the pie chart are what he calls “the 550s,” six-cylinder engines in singles and light twins that fill the gap between the engines that are quite happy on 94 UL and the ultra-high-performance boosted sixes that will be the toughest to fuel with unleaded. Testing will begin later this year on a Continental 550 and d’Acosta said it will take about 18 months."

What good is ASTM if they don't even know if it will work reliably in the Continental and big Lycoming engines? - I mean Seriously?

how many planes as UL94 totaled? 

[Pinecone]

On 9/5/2025 at 10:56 AM, EricJ said:

The benefit of a consensus standard like ASTM is that it has had eyes on it and approval by a very broad set of stakeholders, including engine and airframe manufacturers, refiners, distributors, etc., etc.  The result is that the likelihood of post-deployment issues goes way, way down. 

This contrasts significantly to the STC process where one guy can do all those functions including being the DER for the FAA.

In what way?

All an ASTM standard means is that you got a bunch of people to agree to make a standard for THAT mix.  It does not address the suitability of THAT mix to the desired use.

Swift still has not changed their stance that the fuel is NOT suitable for a good proportion of the piston fleet.

[1980Mooney]

17 hours ago, gabez said:

how many planes as UL94 totaled? 

I read that damage resulted in about 128 top overhauls of one form or another.  That sounds pretty "bricked".  And this was only because of the meticulous maintenance and recordkeeping of UND.  Who knows how many other engines elsewhere were damaged that went unreported.

The point is that there were unanticipated consequences regardless of ASTM D7547 certification.  And Swift is already hedging whether 100R will work in the high performance portion of the fleet.  They say that they will do about another 2 years of lab/test cell testing.  And even then it may still have unintended consequences in the real world use. 

The first users will be guinea pigs regardless of ASTM approval. Maybe it will work and maybe it won't.

[1980Mooney]

On 9/5/2025 at 12:45 PM, EricJ said:

It now has an ASTM standard associated with it that it can claim compliance to.    This is relevant to acceptance in the entire production and distribution chain as well as insurability of the various pieces.  

 

2 hours ago, Pinecone said:

In what way?

All an ASTM standard means is that you got a bunch of people to agree to make a standard for THAT mix.  It does not address the suitability of THAT mix to the desired use.

Swift still has not changed their stance that the fuel is NOT suitable for a good proportion of the piston fleet.

That is true - they have an ASTM production/manufacturing standard for what so far appears to be (by Swift's own admission/cautions) an inferior knock/detonation preventing fuel.

How many remember when ethanol was first blended into unleaded gasoline?  It had "ASTM" certification.  It also damaged some hoses, elastomers, plastics and caused corrosion in older vehicles.  Older lawnmowers and motorcycles suffered. Owners just had to take it on the chin.

Swift's press release last week claims that ASTM cert was achieved " by the team from Swift Fuels working in collaboration with FAA and numerous OEMs from Lycoming, Continental Aerospace, Rotax, Textron Aviation, Piper, and others, plus testing laboratories and various aviation part suppliers."

• Well if they are working with Continental and Lycoming on the high-performance/ big-6's engines, then why aren't we hearing from them?
  • In all this time, why don't they have test results on this "remaining 25% are more complicated" portion of the fleet?
  • Either they have and the test results are dismal or they have rushed the certification out prior to testing.

BTW - this "remaining 25% are more complicated" portion of the fleet probably consumes 45% of the Avgas.

[Jackk]

Trying to sell “solutions” to non existent problems 

 

Only way any of this snake oil will sell is if government screws with the market and forces us to use this junk.

 

Id rather AOPA / EAA etc start spinning up the lawsuit machine to stop it from getting that far, much rather AOPA spend the money on lawyers and lobbies than sending me a dumb hat or mass mailing paper.

 

 But maybe that’s just me

 

 

reminds me of the corn gas scam

 

 

[Ibra]

1 hour ago, 1980Mooney said:

I read that damage resulted inabout 128 top overhauls of one form or another.  That sounds pretty "bricked".  And this was only because of the meticulous maintenance and recordkeeping of UND.  Who knows how many other engines elsewhere were damaged that went unreported

Did UND share any public data on their story? 

I recall GAMI repeoduced detonation and valve recession with UL94 while 100LL performed well (likely true in extreme scenario), then Lycoming blamed aromatics in 100R (likely wrong), Swift blamed "operator technique" (likely true as UND were very aggressive with engines)

http://avweb.com/aviation-news/swift-recommends-limiting-peak-or-lean-of-peak-operations-with-94ul-for-now/

I went with the latter: UND students don't know how to manage engines (I recall reading the SOP is to red-box at 20ROP or peakEGT when using 70%-80% power while CHT north of 450F)

For engines, with all these initial "roll-out of new fuel" one has to be careful with selection bias on the operator aide, like all sort of feedbacks sometimes the issue is NOT the product but "A SPECIFIC" user, we will see more and more of operators getting into engine management education as more alternative fuels gets introduced. For airframe, things are different, the user has no choice if the fuel is bad for paint, pipes, sealants.

In terms of costs, I need to decide between engine overhaul (60k$ job)? or tank reseal with new paint (25k$+25k$ job)? in the meantime, I am fine with keeping CHT < 380F, I already do this when using 100LL, happy to pay +2GPH or -10kts to achieve it 

 

Edited Monday at 05:51 PM by Ibra

[Fly Boomer]

2 hours ago, Jackk said:

Only way any of this snake oil will sell is if government screws with the market

I've been kind of "back burner" concerned about this fuel situation, but this is reassuring.

[gabez]

Swift discusses the UND issue

[Ibra]

1 hour ago, gabez said:

Swift discusses the UND issue

Thanks, I watched that part (starts at 40:00), as expected UND were abusing their engines…even with 100LL they would have the exact same problem (they did not even run 50% vs 50% of fleet on 100L vs UL94) 

Definitely not aromatics as Lycoming suggested, I did run the same Archer with same engine on UL91 (Avgas available in Europe, basically 100LL without TEL and no aromatics) and many times using SP98 auto-fuel (full of aromatics, sort of EN228/AKI93 with even lower MON 87 octane rating), however, I flew richer than 100ROP and I swear, I never ever let CHT slip above 380F, that Archer still fly using Mogas with no issues ! 

Swift claimed no one else had valve recession problems using UL94 in the last 10 years, except  UND (they have engines replaced regularly on warranty anyway even with 100LL )

 

Edited Monday at 10:06 PM by Ibra

[Pinecone]

19 hours ago, Jackk said:

Trying to sell “solutions” to non existent problems 

Only way any of this snake oil will sell is if government screws with the market and forces us to use this junk.

Id rather AOPA / EAA etc start spinning up the lawsuit machine to stop it from getting that far, much rather AOPA spend the money on lawyers and lobbies than sending me a dumb hat or mass mailing paper.

 But maybe that’s just me

Yes, you can stick your head in the sand about it, but TEL WILL go away.  Either it will be banned or THE (yes, there is only one) factory will shutdown or burn down.   Without a replacement, we can all park our planes and they will not be worth anything other than as beer can material.

We are already flying on a waiver of the ban of TEL from the 70s for other gasoline using lead.

[MikeOH]

3 hours ago, Pinecone said:

Yes, you can stick your head in the sand about it, but TEL WILL go away.  Either it will be banned or THE (yes, there is only one) factory will shutdown or burn down.   Without a replacement, we can all park our planes and they will not be worth anything other than as beer can material.

We are already flying on a waiver of the ban of TEL from the 70s for other gasoline using lead.

And, yes, you can continue to scream "the sky is falling" but the reality is that there is NO way the US Government is going to effectively allow all GA piston aircraft to be grounded over this ridiculously tiny amount of lead.  There is simply too much money at stake from COMMERCIAL GA flying, not to mention the critical services to society that it provides; it's not just spoiled rich folk in 'private' planes.  Like all government 'programs' and 'mandates' this one is also subject to the whim of 'kicking the can down the road' if a suitable alternative is not actually available by the deadline.

And, TEL is not exactly cutting-edge rocket science to manufacture...and there are other sources around the world making it (India comes to mind). They may not be CURRENTLY 'approved' for use for US bound fuel, but it's a red-herring to act like the "only one source" is putting the entire supply of 100LL at daily risk of GA destruction.  That's just fear mongering.