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  #31  
Old 05-29-2021, 06:39 AM
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newt newt is online now
 
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Originally Posted by rv6ejguy View Post
Of more concern may be that the aromatics are pretty high on the solvent scale and may not be compatible with existing fuel system materials plus they are fairly nasty to humans both combusted and in in their natural liquid state. Maybe you're eliminating the lead in exchange for other demons here.
I seem to recall that one of the failed PAFI candidates (the Shell one?) seemed to run okay in the engines, but was found to also function extremely well as a paint stripper.

Which immediately took it out of contention.

- mark
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  #32  
Old 05-29-2021, 04:15 PM
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I got a reply to an email I sent to Swift. Their 100R fuel program is still underway with the FAA though it seemed that the agency wasn't exactly expediting progress on this. I guess we knew this last part already since it was 2018 when PAFI didn't result in any UL avgas. It will involve an STC just like the the GAMI effort as I understand it. The FAA sounds like it might be lukewarm to the STC idea, still looking for the perfect UL avgas which meets the current ASTM spec that 100LL does instead. I hope the FAA allows a slightly revised spec to get this fuel to market sooner rather than later.

And the latest form the FAA showing PAFI itself isn't dead but about to be revived (if any of the fuel companies still want to play inside it): https://www.faa.gov/about/initiatives/avgas/

I get the impression that the fuel companies are all a bit fed up with the foot dragging and intransience on the part of the FAA.

https://www.avweb.com/insider/going-...ared-to-100ul/
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 449.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
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Last edited by rv6ejguy : 05-29-2021 at 04:19 PM.
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  #33  
Old 05-31-2021, 03:18 PM
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I received a reply form GAMI today on their G100UL fuel today. They reported that they are very close to having their STC approved and that specific gravity is only very slightly higher than 100LL and that the heating value of their fuel is slightly higher as well.

Good news, depending on what "very close" means with the FAA.

I wish these guys well. Next hurdles will be production and distribution of the product on a large scale.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 449.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
https://www.youtube.com/channel/UCiy...g2GvQfelECCGoQ


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  #34  
Old 05-31-2021, 03:59 PM
Freemasm Freemasm is offline
 
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There is a very steep increase with the first small amount of TEL. From Liston.
Can you get me smarter in how to read this? Knock limited power, increase per cent (sic? Percent?)? I would thought it would be referenced to CR. I guess I’ll oh could extrapolate if you assumed each engine minimized any detonation margin. What are they saying that I’m missing?

I’ll state again if the heating values meet/exceed that of 100LL, the SG increase is very manageable; even advantageous. STCs would be OK but I don’t know if any of the potential providers will lay it on the table regarding “mixability” issues with other offerings. This would hurt us. A single source provider for the approved 100LL replacement will probably take advantage of that market position. If the STC’d providers will allow the aforementioned mixing, the completion can only help us users.
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  #35  
Old 05-31-2021, 06:20 PM
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A lot of testing in the '50s and even indeed today use single cylinder CFR engines to explore detonation limits with different fuels. The CR can be easily changed on these or in the case of aviation fuel testing, supercharged versions can be used to establish the knock limits of various fuels by raising MAP until knock occurs.

The graph shows that with the addition of 3.6 ml of TEL, the knock hp threshold was raised by 48% over the base 100 octane fuel with no lead.

It looks to me from reviewing various comments that both Swift and GAMI will be using STCs to get their fuel to market for certified aircraft.

Per cent was an older form of percent, more often used in Britain and the colonies. Liston's book came out in the '40s and is one of the best texts every published on aviation power plants. A little history on Liston:

"Professor Joseph Liston (BSME '30, MSME '35) joined Purdue from the faculty of the University of Oklahoma Mechanical Engineering Department. He was a former naval aviator, and pioneered landings on aircraft carriers. Professor Liston's primary interest was in aircraft propulsion, and he developed several outstanding power plant design courses and test facilities during the 1940s. Professor Liston remained on the Purdue staff until retiring in 1972."
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 449.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
https://www.youtube.com/channel/UCiy...g2GvQfelECCGoQ



Last edited by rv6ejguy : 05-31-2021 at 08:17 PM.
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  #36  
Old 05-31-2021, 06:56 PM
PilotjohnS PilotjohnS is offline
 
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Quote:
Originally Posted by rv6ejguy View Post
A lot of testing in the '50s and even indeed today use single CFR engines to explore detonation limits with different fuels. The CR can be easily changed on these or in the case of aviation fuel testing, supercharged versions can be used to establish the knock limits of various fuels by raising MAP until knock occurs.

The graph shows that with the addition of 3.6 ml of TEL, the knock hp threshold was raised by 48% over the base 100 octane fuel with no lead.

It looks to me from reviewing various comments that both Swift and GAMI will be using STCs to get their fuel to market for certified aircraft.
I hope they dont go after the same market. If there are three suppliers (normal avgas, GAMI and Swift, a fractured market may mean nobody survives, that's my fear). Maybe Swift and GAMI can join forces???
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  #37  
Old 05-31-2021, 08:03 PM
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I don't see Swift and GAMI joining forces as they are competitors. I see possibly both meeting a slightly revised ASTM spec and having approval to be mixed if both make it to market, much like you mix different brands of 100LL right now.

My take, and I could be wrong, is that the FAA initially thought and wanted the new UL avgas to meet the current ASTM spec for 100LL exactly, so drop in, no STCs. Years down the road with many dollars spent, that looks unlikely as both visible players (not sure where Shell and the Texas guys are at) are working on STC approvals.

I see normal 100LL quickly going away once UL production and distribution meet demand.

This is a huge market for either GAMI or Swift which are pretty small companies in this context and certainly will need refining and distribution partners.
Shell could drop into the market at any time too and change the whole landscape.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 449.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
https://www.youtube.com/channel/UCiy...g2GvQfelECCGoQ



Last edited by rv6ejguy : 05-31-2021 at 08:23 PM.
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  #38  
Old 05-31-2021, 09:13 PM
NinerBikes NinerBikes is offline
 
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Depends on ignition timing. With programmable EIs, some folks are running up to 9 to 1 on on mogas which is lower octane than this. You just limit timing a bit at high MAP and have full advance in cruise where MAP is lower.

You take a small HP hit at TO power and sea level. Cruise performance at altitude is unaffected from what we see.

Rotax runs water cooled heads on their engines, and run just fine on 91 octane Mogas with up to 10% ethanol. Compression ratio, I believe, is 10.8 : 1 on a
Rotax 912 ULS.
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  #39  
Old 05-31-2021, 10:25 PM
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Lycomings are running on mogas too but that's not really part of this discussion.
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 449.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
https://www.youtube.com/channel/UCiy...g2GvQfelECCGoQ


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  #40  
Old 06-01-2021, 04:12 AM
David Z David Z is offline
 
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We need a fuel that keeps the TIO-540 happy at 49inHg, the 10:1 compression performance engines as well as the not so crazy engines that can burn mogas. Currently 100LL is that fuel. It has high vapour pressure to handle the poorly laid out fuel system in most airplanes (sucking it all the way to engine driven pump) and not too expensive.

When the one article above mentioned modifying a race fuel, I got scared of price. Race fuel can be astronomically expensive, $10/gallon + is normal.
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