GAMI presentation from OSH '24

[N201MKTurbo]

I have thought for a while, that auto fuel should be sold by the BTU instead of the gallon. The higher the ethanol content, the lower the mileage. Most people don’t pay attention to these things, but you are getting ripped off when they up the ethanol content.

[FlyingDude]

2 hours ago, Shadrach said:

00LL’s days/years are numbered especially since those who seek to ban it will be minimally affected by its absence (e.g. non flying public and politicians who prefer to burn tax payer purchased jet-A).

that's what I assumed too, but if you read the article shared above on the new Avgas supplier out of India, they expect drones to be a new market.  So, the diminishing pool of our turbobugsmashers is not the only customer of this market. 

[FlyingDude]

Maybe it was covered elsewhere, has Shell Vpwr nitro ever been considered?  99octane, <5% alcohol.  

Can't we just overhaul our injection systems with ethanol-friendly rubber?  I doubt 5% ethanol will cause significant vapor lock...

[FlyingDude]

On 8/3/2024 at 9:50 PM, A64Pilot said:

Something that crop dusters put inside the tank eats fuel tank sealant over time

Not ethanol...  Proseal resists alcohol...

[Shadrach]

32 minutes ago, FlyingDude said:

that's what I assumed too, but if you read the article shared above on the new Avgas supplier out of India, they expect drones to be a new market.  So, the diminishing pool of our turbobugsmashers is not the only customer of this market. 

To be sure there are market pressures on the manufacturing side that make a new refiner a welcome edition. However, I think the problem in the US is going to be regulatory both locally and the federal level. it matters little that we have an additional manufacturer if the private sale of the product is prohibited.

[Pinecone]

5 hours ago, GeeBee said:

Yeah you ought to see what ethanol fuel does in marine applications. In particular boats with fiberglass tanks. They became tanks of goo and did you know ethanol fuel starts "phase separation" after about 30 days? Go to any marine store and you will see several brands of "ethanol fuel stabilizers". I am fortunate in that all the marinas and some gas stations in my area sell non-ethanol 90 octane. I wince when I see a boat on a trailer filling up at Costco. He will be in the maintenance shop in short order. Same problems with outdoor power equipment which is why they sell "True Fuel" at Home Depot.

A local Stihl dealer swears by StarTron additive.  Both as a stabilizer and to mitigate the issues with ethanol.  Seems it works GREAT on small motors.

[GeeBee]

20 minutes ago, Pinecone said:

A local Stihl dealer swears by StarTron additive.  Both as a stabilizer and to mitigate the issues with ethanol.  Seems it works GREAT on small motors.

Yes, it is one of the good ones. I use non-ethanol 90 so I don't need it.

[GeeBee]

48 minutes ago, FlyingDude said:

Maybe it was covered elsewhere, has Shell Vpwr nitro ever been considered?  99octane, <5% alcohol.  

Can't we just overhaul our injection systems with ethanol-friendly rubber?  I doubt 5% ethanol will cause significant vapor lock...

Nope, not enough octane. 100LL can actually be as high as 104 depending on mixture. The warbird guys are drooling over G100UL because it represent higher octane for them.

[BlueSky247]

3 hours ago, Shadrach said:

I am sure George had his reasons for going the STC route. I don’t know what they were, but my guess is it had to do with politics and process.

 

Just an fyi, He specifically answered that question from an audience member in the talk at Osh that he went that route because he felt going to the ASTM would basically be stonewalled.

[N201MKTurbo]

1 hour ago, FlyingDude said:

Not ethanol...  Proseal resists alcohol...

Not true. I have used denatured alcohol to remove sealant. it works almost as good as MEK.

[FlyingDude]

46 minutes ago, N201MKTurbo said:

Not true. I have used denatured alcohol to remove sealant. it works almost as good as MEK.

Denatured alcohol is not pure ethanol... It has a bunch of nasty stuff including methanol that makes your eyes go blind.  I kind of don't believe that denatured alcohol is as good as Mek when even acetone was better than ethanol but not as good as mek. I clean proseal with 99-% isopropyl to remove and debris and loose parts... 

[DonMuncy]

3 hours ago, M20F said:

I could probably get another 20-30HP in the MG shifting to E85 but I am lazy.   

What kind of MG?

[Shadrach]

6 hours ago, M20F said:

No it was in response to auto racing (follow the thread), don’t be obtuse.  That being said till I am guessing about 10K you could get away with E85 in an airplane.
 
I could probably get another 20-30HP in the MG shifting to E85 but I am lazy.   

With stock pistons? Are you running a turbo? 

[M20F]

53 minutes ago, Shadrach said:

With stock pistons? Are you running a turbo? 

Supercharger 8.8:1 with 5lbs boost with cast pistons and decent but cheap internals.  I have a friend that has now 10k miles on a bone stock (with we are guessing 100k miles on the motor) running 30lb turbo.  He has actively been working to destroy the engine and is failing. 
 
To clarify my original post 10K and below would in my small mind work for E85.  Altitude and temperature are the big challenges to 100LL.  Working on limiting either or both would be a reasonable middle ground.  Most don’t fly above 10K or below 0F.  

[M20F]

4 hours ago, DonMuncy said:

What kind of MG?

71, Moss Supercharger, good/cheap internals.  Road cam (can’t remember numbers) that pulls great above 3K in 3/4 on the Highway.  
 
The real dollars are in the brakes/suspension, I eat everything running Blood Mountain. 

[GeeBee]

11 hours ago, M20F said:

To clarify my original post 10K and below would in my small mind work for E85.  Altitude and temperature are the big challenges to 100LL.  Working on limiting either or both would be a reasonable middle ground.  Most don’t fly above 10K or below 0F.  

You are forgetting these are air cooled engines.

[FlyingDude]

18 hours ago, Shadrach said:

I think the problem in the US is going to be regulatory both locally and the federal level.

That's your personal opinion.  The whole world is waging war against oil and passed laws saying all new vehicles after a certain year will be electric.  Some European carmakers asked us in the auto industry to start working on removing even the leaded 12V battery from vehicles, even if that lead is well recycled and therefore not really an environmental hazard unless some dumbass puts it in yard waste.  None of these items gained traction in US.  You'll be surprised, there are many Europeans that hate and try to act against wind turbines and conversion of arable land into solar farms.  So, if the environmentally purist rest of the world is silent on eliminating leaded avgas, so what makes you think that we'll be the first ones to eliminate Pb altogether?  Because we have the fattest and loudest Karens? 

[N201MKTurbo]

11 hours ago, M20F said:

Supercharger 8.8:1 with 5lbs boost with cast pistons and decent but cheap internals.  I have a friend that has now 10k miles on a bone stock (with we are guessing 100k miles on the motor) running 30lb turbo.  He has actively been working to destroy the engine and is failing. 
 
To clarify my original post 10K and below would in my small mind work for E85.  Altitude and temperature are the big challenges to 100LL.  Working on limiting either or both would be a reasonable middle ground.  Most don’t fly above 10K or below 0F.  

I don't understand your concerns with altitude and temperature. The octane number of a fuel is important for anti-knock. Detonation is caused by a combination of pressure and temperature. The higher the combustion chamber pressure and the higher the temperature, the more likely it is to detonate. With a NA engine the pressures and temperatures decrease with altitude. The higher you go the less octane you need. Over 10,000 feet any NA engine will run fine with UL94. 

As far as ethanol is concerned, octane number isn't the concern. It has a high octane number. the problem is its low energy content, its material compatibility issues and its propensity to absorb water.

[Pinecone]

18 hours ago, FlyingDude said:

Maybe it was covered elsewhere, has Shell Vpwr nitro ever been considered?  99octane, <5% alcohol.  

Can't we just overhaul our injection systems with ethanol-friendly rubber?  I doubt 5% ethanol will cause significant vapor lock...

You have to understand Octane ratings.

AVGAS is rated with two numbers, a Lean Rating and a Rich rating.  Thus 80/87.  100LL replaced 100/130 AVGAS.   With the LL added, they dropped the Rich rating number from the name.

MOGAS also has two ratings that differ with the test conditions (air temp, oil temp, etc).  They are Motor Octane Number (MON) and Research Octane Number (RON).  In the US up until the early 70s (IIRC) the number on the pump was RON.  And it is still today in most of the world.  So you will see 97 or 98 octane pump gas in Europe. But the US switched to AKI (Anti Knock Index).  It is the average of RON and MON ((RON+MON)/2).  FYI, MON is the more stringent test, yielding a lower number.  There is no specific relationship between RON  and MON, so you could have two fuels with a 90 AKI, one with 80/100 and the other with 85/95.

But, the high performance German car makers found an issue with engine damage even though the RON met or exceeded the requirements.  This occurred in long high speed runs.  They found it was due to too low of MON.  So they required drivers to use fuel where the MON was no more than 10 points lower than the RON.

Most MOGAS meets the requirement.  So, from the example above, you won't fine 90 AKI that is 100 RON and 80 MON.  It would be 95/85 or tighter.  That means that 97 or 98 Euro gas is actually around 92 - 93 AKI.  Hmmm, sound familiar?

It turns out that the tests for MON and Aviation Lean rating are pretty much the same.  So we can compare fuels with assuming they are the same.

So a 100 US pump MOGAS is 100 AKI.  Which means it is 95 or so MON.  We need a minimum of 100 MON (so that would be 105 AKI) fuel, but most is blended to a slightly higher 104 to be sure it is not too low.

One interesting thing with G100UL is that it is rated at something like 104/154.  So the Rich rating is higher than even the 115/145 AVGAS, which is only available for things like the Reno Air Races.  But used to be used in the piston airliners.

[FlyingDude]

6 minutes ago, Pinecone said:

That means that 97 or 98 Euro gas is actually around 92 - 93 AKI. 

Yes, that part I knew.  I knew about the MON/RON and AKI from work.

It turns out that the tests for MON and Aviation Lean rating are pretty much the same. 

I did not know that part.

I don't know about you guys, but I'm actually excited about this G100UL.  

 

[Pinecone]

Just now, FlyingDude said:

Yes, that part I knew.  I knew about the MON/RON and AKI from work.

It turns out that the tests for MON and Aviation Lean rating are pretty much the same. 

I did not know that part.

I don't know about you guys, but I'm actually excited about this G100UL.  

 

So am I.  And the warbirds guys are drooling for it, as it allows full rated power on those engines that were designed to run on 115/145.

[EricJ]

2 hours ago, N201MKTurbo said:

As far as ethanol is concerned, octane number isn't the concern. It has a high octane number. the problem is its low energy content, its material compatibility issues and its propensity to absorb water.

And it spoils over time, i.e., it has a very limited shelf life.    Many of my racing friends around here have been running ethanol blends (usually E85) for many years, buy it by the barrel, and have to very carefully plan when to buy the barrel and manage their consumption so that they use it fast enough that it doesn't go bad.

For those wondering why ethanol is desirable for making more power when the energy content is lower,  if you pump more of it in (with larger injectors) and tune appropriately, you can make significantly more power with it, even with an NA motor.  It runs cooler, too, so there's some win-win.    Since you need to flow more of it to make the power, your tank doesn't get you as far, but if what you want is output power it's a good way to do it.   The gasoline/ethanol blends wind up with higher octane numbers than running either by themselves, so it's a popular way to make more power on a track when the rules allow.

The downsides are significant enough to keep it out of general use, though, especially the material compatibility issues, which also seems to be one of the significant concerns with G100UL.

[N201MKTurbo]

Just to expand on what Eric said. The octane number has no direct impact on how much power your engine makes. It does have an impact on how much power your engine can make. A higher octane fuel allows you to increase the cylinder pressures and temperatures without detonation. An engine which is tuned for a lower octane fuel will not make more power if you use a higher octane fuel. You have to re-tune the engine to use the higher octane. Most modern EFI and electronic ignitions will monitor the engine knock and advance the timing until it starts to knock, thus increasing its output power.

If we had this type of ignition system on our engines, it wouldn't be able to make the same power with lower octane fuel, it would only be able to roll the timing back until it stopped knocking. So there is no real advantage to a modern electronic ignition system with regard to full power operation. It can't do any more than just retarding the fixed timing, which is set for full power operation. An electronic ignition can increase the efficiency of the engine at low power operation.

[M20F]

7 hours ago, N201MKTurbo said:

I don't understand your concerns with altitude and temperature. The octane number of a fuel is important for anti-knock. Detonation is caused by a combination of pressure and temperature. The higher the combustion chamber pressure and the higher the temperature, the more likely it is to detonate. With a NA engine the pressures and temperatures decrease with altitude. The higher you go the less octane you need. Over 10,000 feet any NA engine will run fine with UL94. 

As far as ethanol is concerned, octane number isn't the concern. It has a high octane number. the problem is its low energy content, its material compatibility issues and its propensity to absorb water.

My understanding is ethanol starts to break down at higher altitudes due to temps and pressure.  It isn’t a detonation concern just the fuel itself breaks apart. 

[N201MKTurbo]

19 minutes ago, M20F said:

My understanding is ethanol starts to break down at higher altitudes due to temps and pressure.  It isn’t a detonation concern just the fuel itself breaks apart. 

Ethanol is a pure chemical, I'm not sure what it would degrade into. In most cases chemicals will decompose at higher temperatures. E85 is ethanol and gasoline mixture, I'm not sure what happens to that. Ethanol has a higher vapor pressure, it will evaporate more at higher elevations. 

I was googling E85 deteriorating and couldn't find much. It is amazing how many people think E85 is 85 octane...