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08-27-2018, 05:50 AM
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Join Date: Dec 2011
Location: Alpharetta, Ga
Posts: 212
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100LL Future and Engine Purchase Concerns
I'm probably a year or so away from looking for some type of propulsion system for my -14 project  . As decision time gets closer I become more concerned about what I?m hearing about the uncertain future of 100LL. When I discuss these concerns with others, the typical statement I hear is ?they?ll come up with something?. Well, this issue has been around for many years now, and so far a suitable replacement is yet to be produced. Apparently, it?s a little more challenging than expected. I wonder will the whole 100LL phase out plan just go away, or will some type of ?band-aid? fuel be introduced until engines can catch up with the times. I realize this can be a controversial subject, and I may be overreacting. I imagine the folks that already own the 100LL burning engines are likely hoping for some type of 100LL replacement, or that the FAA/EPA will give up on the AVGAS phase out plan all together. On the other hand, the group that have yet to buy engines are hoping for some type of miracle, and a new engine will be developed that doesn't require 100LL,..and will be similar in weight, shape and fuel burn of the Lycomings. Big wish list I know.
Again, I may be overreacting to this, but this 100LL thing has kind of taken the wind out of my sail for my build motivation. I enjoy my project, and have no intention of throwing in the towel. However, I just can't bring myself to buying an engine that requires a fuel with an uncertain future.
I would love to put a small turbine, or diesel up front. However, I just don't believe the current options are a good fit for the RV-14. I'm keeping my fingers crossed though!
It appears the most likely scenario may be sticking with the lycoming and modding the engine to burn something other than 100LL. I've heard the engine for the 14 (Lycoming IO-390) with a compression of 8:7:1 is just over the limit for running a lower octane unleaded fuel. The 390 would need to be derated, and have hardened valve seats. I have not researched what the derated HP would be, or if it would it be sufficient for the RV-14. My knowledge of piston airplane engines is pretty basic, but I'm learning.
So...anybody else out there have issues with buying an Avgas burning engine given the 100LL issue, or is it just me??
Here's some links that help "fuel" my concerns:
FAA PAFI program update https://www.faa.gov/about/initiatives/avgas/
AVGAS facts and Future
https://www.shell.com/business-custo...-30071515.html
100LL Replacement or not?
https://www.avweb.com/blogs/insider/...-230953-1.html
The need for leaded Avgas (This site has interesting info of all kinds)
http://www.epi-eng.com/aircraft_engi...e_of_avgas.htm
and on the R&D front:
What happened to this NASA project?
https://www.grc.nasa.gov/WWW/PAO/PAIS/fs01grc.htm
Give Continental credit..at least they're trying!
http://www.continentalmotors.aero/di...l-engines.aspx
Turbine Aeronautics (wishing these guys luck!)
https://www.turb.aero/
PBS (there was one of these in a 10) very pricey and fuel burn issues. would love one though!
http://www.pbsaerospace.com/our-prod...rboprop-engine
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08-27-2018, 06:23 AM
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Join Date: Nov 2017
Location: Orlando
Posts: 195
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GAP Piston Engine
This is all my my ancient memory banks. The specs were quite aggressive and any qualifying product would be drool worthy. A very long time ago, a Continental Engineer working on the GAP piston engine told me (right or wrong) that the engine had met all of the design criteria. If just one of the OEMs would pick it up, it would go into production. Assuming that was true, they missed the market; not their fault. The spec called out a 200HP engine. At that time, the exp and commercial market were going to bigger powerplants. Continental was subsequently sold to the Chinese so it's doubtful we'll ever see anything for our market from these tax dollars.
Maybe someone else has better info/memory. Hopefully they will reply.
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08-27-2018, 06:28 AM
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Join Date: Mar 2008
Location: houston, texas
Posts: 900
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Not at all.
I don't think you will get many answers on this one as no one knows what the final look of the fuel change over will be at this time. I can say that many of us have planed for this many years ago using our dealings with engines, engine parts and systems. You have a good starting point by looking at the compression ratio as a guide. The new fuels are targeting the standard of 8.5:1 as that is the set that most of the old aircraft engines have used down throw the years. We know that we can burn 92-93 Oct. UL fuels in these engines now. And if you look the engine companies are starting to go back and approve the use of Mow. gas of this grade in these new and older engines with that set-up or configuration. The newer FAA approved fuels will have to target at least that market if not higher Octane ratings. So I have no personal problem with an engine that burns fuel of that grade or standard. I personally think that the fuel or fuels that will be given the green light will be closer to the 100 Octane level in the end. WE built our fuel system to be able to be used with any "E" fuels for just these reason and compromised by putting 9:1 compression pistons in, instead of 8.5:1.
The big catch in all of this is "WARRENTY", or who will pay if the new fuels do damage to my nice costly engine. If you don't have big sponsors and have to swallow that pill for yourself, I can more than see the stress this would generate. I think they have good replacements already, it is I think the liability and the jockeying for a place at the profit table that is the thing that is dragging out the time table. In the engine world, fuels are often hand blended to meet the need of that use. Some of us still do it a little.
This may not help you but it is another two pennies to throw in the pot.
Yours, R.E.A. III # 80888
Last edited by Robert Anglin : 08-27-2018 at 06:36 AM.
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08-27-2018, 07:03 AM
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Join Date: Nov 2007
Location: Jacksonville,Fl. 32246
Posts: 270
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My $.02 if you are early enough, use high pressure auto fuel injection hoses in any thing fuel related and make provision for a possible fuel return.This type of
thinking allows for any fuel/system in future. I know it?s not politically correct,
but an acquaintance used high test auto fuel in his Bonanza for 30 years !
__________________
Tomcat RV4
RV4 gone to RV heaven !building Zenith 701
dues paid and worth every penny
Life is uncertain -Eat desert first !
U F O Member since Dec 2017
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08-27-2018, 07:39 AM
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Join Date: Oct 2006
Location: Garden City, Tx
Posts: 5,145
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I'm rolling up on 275 hours now on my IO360 running Walmart-grade 91 premium autogas with ethanol on 8.7:1 compression with no issues. I did build the entire fuel system on the airplane with ethanol exposure in mind and eliminated all but one natural rubber O-ring which I found a couple weeks ago, it finally started leaking at about 250 hours.
The engine is quite happy burning 91E10, in-flight performance is within a percent or two of the 100LL standard, I can't tell the difference without digging into the Dynon performance data on a long cross-country.
Handling the fuel here is going to be the trick for you and most others though. I am based on a private strip just over 30 miles from the nearest "real" airport with fuel - so I have my own tank on my strip. I took a used milk container, 125 gallons stainless, and steam cleaned it, set it on a 275-gallon chemical tote frame so I can pick it up with forks on a tractor, and put a pump and battery on the frame. I can fork it onto the back of my pickup and take it to town for a fill when needed, easy-peasy.
__________________
Greg Niehues - SEL, IFR, Repairman Cert.
Garden City, TX VAF 2020 dues paid 
N16GN flying 700 hrs and counting; IO360, SDS, WWRV200, Dynon HDX, 430W
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
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08-27-2018, 07:42 AM
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Join Date: Nov 2017
Location: Orlando
Posts: 195
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Be careful here
Quote:
Originally Posted by Tomcat RV4
My $.02 if you are early enough, use high pressure auto fuel injection hoses in any thing fuel related and make provision for a possible fuel return.This type of
thinking allows for any fuel/system in future. I know it’s not politically correct,
but an acquaintance used high test auto fuel in his Bonanza for 30 years !
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I don't like disputing people and hate the back and forth that ensues but please be careful here. Your last sentence is a bit cavalier in my opinion. Most aviation engines are designed to operate on relatively low octane levels. MoGas is fine for that application. Octane rating does not change Specific Fuel Consumption (though ethanol f's that up). Airframes have to be designed (certified where applicable) for the fuel as well. Most MoGas fails the Reid Vapor Pressure requirement so use in a low wing aircraft without proper design provisions can have serious consequences. "Drawing" fuel through a line can easily cause vapor lock. I also have known of people that put MoGas into airframes that were not designed/certified for such (the bell curve exists in every population.) It works fine until it suddenly doesn't. It's always the alligator you don't see that gets you.
Fly safe.
Last edited by Freemasm : 08-27-2018 at 07:45 AM.
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08-27-2018, 07:53 AM
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Join Date: Mar 2017
Location: Birmingham, Alabama
Posts: 1,643
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Quote:
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As decision time gets closer I become more concerned about what I’m hearing about the uncertain future of 100LL.
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I don't think the FAA or anyone else is going to ground the entire GA fleet until everybody upgrades to a new fuel system. I'm sure there will be a transition period where new airplanes will be required to run the new fuel to get their pink slip. Then, over time, as supply and demand works its magic from gradual transition it will force the prices of 100LL to rise and will push folks to upgrade their fuel systems/engines. I think it's safe to say build on!
__________________
RV-14A #140376
N196 (Flying)
2019 Bronze Lindy
Last edited by bkervaski : 08-27-2018 at 08:03 AM.
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08-27-2018, 08:14 AM
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Join Date: Apr 2012
Location: Pound, VA
Posts: 182
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Quote:
Originally Posted by Mudfly
I?m hearing about the uncertain future of 100LL.
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Just a few years ago their was major concern (worry) we were about to run out of ALL petroleum (Peak Oil). Don't worry about 100LL.... worry about choosing a reliable engine with reliable systems... get the best available today that you can afford.
Quote:
Originally Posted by Mudfly
Again, I may be overreacting to this, but this 100LL thing has kind of taken the wind out of my sail for my build motivation. I enjoy my project, and have no intention of throwing in the towel. However, I just can't bring myself to buying an engine that requires a fuel with an uncertain future.
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No fuel has a certain future. But, before the EPA tries to ban 100LL they'll try (again) to beat coal, woodstoves, and diesel. There are many thousands of 100LL engines in service and nobody has a replacement fuel... its not a priority. Just fly the heck out your 100LL machine and wear it out before a replacement comes along. My guess is we've all got at least 20 years.
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08-27-2018, 08:21 AM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Not a definitive answer, but FWIW
The EPA and FAA have been battling and saber rattling this since lead was removed from cars. I worried about that too, but proceeded ahead with my M1B. The serious issues to be resolved for a replacement fuel are for turbocharged engines. Many are out there and cost a lot more than our normally aspirated units. Owned by people with lawyers.
My invested opinion was to build on, fly and enjoy. If it becomes an issue there is a lot of pressure to apply to the situation, politically, (AOPA, EAA, etc) and technically.
On an optimistic note, I am sure that Ross will have a fully developed EFI system ready with knock sensors, O2 sensors and full timing control with diagnostics (OBD-X) ready for the task. 
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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08-27-2018, 09:18 AM
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Join Date: Jan 2005
Location: NC25
Posts: 3,507
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What Lycoming has to say
I like to go back to the manufacturer of the engine to see what they have to say.
Lycoming on Unleaded fuel part 1.
Lycoming on Unleaded fuel part 2.
Lycoming on Unleaded fuel part 3.
Lycoming Service Instruction 1070Z.
If that is too much to read, most of the parallel Lycoming engines (150, 160, 180 HP) used in our RVs will operate just find on alcohol free premium auto fuel.
As a side note, the Superior Vantage 180 HP engine was certificated on 100LL and auto fuel. Check the type certificate data sheet. That engine is same bore and stroke as the Lycoming and the parts used to fabricate it are for the most part FAA / PMA approved for Lycoming engines.
__________________
Gary A. Sobek
NC25 RV-6 Flying
3,400+ hours
Where is N157GS
Building RV-8 S/N: 80012
To most people, the sky is the limit.
To those who love aviation, the sky is home.
Last edited by RV6_flyer : 08-27-2018 at 09:19 AM.
Reason: used not use
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