Based on the G100UL fuel leak thread what's your position?

[Schllc]

2 hours ago, N201MKTurbo said:

The only way to make our engines work on a reasonable unleaded fuel (UL94) is to reduce the cylinder pressure. This can be done with a MP limitation, a timing reduction or lower compression pistons. All of these things will reduce the engine power a bit. There is no modern computer magic that can change any of this.

I don't believe this is true.  The mercury outboard engines developed high pressure injection, this would address the detonation issue.  It seems to me that the challenges of altitude, compression and power are much simpler than a designer fuel.  But the larger point is that seeking new fuel has yielded nothing productive after all this time.  Other options need to be considered.

[A64Pilot]

29 minutes ago, Schllc said:

I don't believe this is true.  The mercury outboard engines developed high pressure injection, this would address the detonation issue.  It seems to me that the challenges of altitude, compression and power are much simpler than a designer fuel.  But the larger point is that seeking new fuel has yielded nothing productive after all this time.  Other options need to be considered.

Yes, absolutely, the reason Diesels don’t detonate themselves to death because Jet and Diesel is very low octane is that there isn’t any fuel there, once running combustion in a Diesel begins arguably the moment fuel is introduced, this is what constrains the RPM on a Diesel as the higher the RPM the less time you have to complete injection.

So enter Mazda with their spark controlled compression ignition gasoline engine, even though it’s compression ignition it doesn’t detonate, I believe it has arguably essentially a Diesel’s common rail injection system and injecting fuel directly in the cylinder at the precise moment burn should begin, mimicking a Diesel.

So yes obviously very high compression gasoline engines are possible running on 87 Octane or lower car gas, but of course that’s an entirely new engine to certify.

https://www.mazdausa.com/discover/what-you-need-to-know-about-the-compression-ignition-engine

https://www.caranddriver.com/news/a15339942/mazdas-gasoline-skyactiv-x-spcci-engine-explained/

Edited February 19 by A64Pilot

[N201MKTurbo]

1 hour ago, IvanP said:

In other words, take well runnig high compression high performance engines and hobble them to perfom like C-172 at the altar of the environmetalist gods  

Aside from the politics, it doesn’t really have to hobble our planes that much. Let’s say the MP was limited to 25” would that be the end of the world? It would affect us turbo folks a bit more than the NA folks. Nobody cruises at 100% power anyway.  Our cruise power is usually limited by temperature anyway, and the changes would have no impact on cruise performance. 
 

So, you cruise at about 225 HP with 100LL. With 94UL you could still cruise at 225 HP, that is well below the power to get detonation. It would only affect your takeoff and climb performance.

[N201MKTurbo]

The warbird guys have a lot of engines designed to run on 145 octane fuel. They are all happily flying along on 100LL with MP limitations.

[IvanP]

48 minutes ago, N201MKTurbo said:

Aside from the politics, it doesn’t really have to hobble our planes that much. Let’s say the MP was limited to 25” would that be the end of the world?

My Bravo climbs well at 34" MAP all the way to FL250. Not sure what the climb rate of a fully loaded plane would be at 25" MAP, but my guess is that it would be pretty pathetic.  Cruising at 25"MAP is OK, but most folks who buy turbocharged planes did not buy them to go slow. 

[Marc_B]

Going by my MAPA key numbers idea, 4" MP drop equivalent to a 10% HP drop...that would equate to about 35% loss of takeoff power for me (39"-->25").

[EricJ]

4 hours ago, N201MKTurbo said:

There is no modern computer magic that can change any of this.

Tuning shops do this every day.   There are experimentals out there that have full-on electronic fuel injection and electronic ignition on Lycoming engines and can adjust fuel/spak map tables just like one does on a modern car.   Nobody wants to make the investment to move this to certificated GA because the market is too small (and shrinking) so that a case for any sort of reasonable ROI isn't practical given the cost of certification.    Lycoming has made some steps in that direction and has been selling their iE2 engine for a while, and the Thunderbolt is apparently the preferred engine for homebuilts now.

I think the cost of certification is and has been the real barrier, not the availability or practicality of the technology, which has been around for almost thirty years now.

[N201MKTurbo]

1 minute ago, EricJ said:

Tuning shops do this every day.   There are experimentals out there that have full-on electronic fuel injection and electronic ignition on Lycoming engines and can adjust fuel/spak map tables just like one does on a modern car.   Nobody wants to make the investment to move this to certificated GA because the market is too small (and shrinking) so that a case for any sort of reasonable ROI isn't practical given the cost of certification.    Lycoming has made some steps in that direction and has been selling their iE2 engine for a while, and the Thunderbolt is apparently the preferred engine for homebuilts now.

I think the cost of certification is and has been the real barrier, not the availability or practicality of the technology, which has been around for almost thirty years now.

Eric, our engines are tuned for 100% power. That’s where the problem is. What is an electronic fuel injection system and an electronic ignition system going to do to make more power without detonation? 
 

There is nothing they can do that we cannot do with what we have. We can adjust spark timing, we can adjust mixture. What else is there? 
 

I guess you could say they can get closer to detonation than we normally get, but how would we get there? Knock sensors have proven ineffective on aircraft engines. Ion current sensing may work. I mentioned it to George Braly once and he called me an idiot. But he was selling pressure sensing spark plugs. Pressure sensing spark plugs would work, but they are very expensive. 
 

So, what are the detonation margins for a certified aircraft engine? I don’t know the answer to that, do you? 
 

It seems to be in FAR 33 sub part D section 33.47 and AC 33.47.

[N201MKTurbo]

Here is a good paper about it:

https://journals.sagepub.com/doi/full/10.1177/14680874211008703

 

[Schllc]

7 minutes ago, N201MKTurbo said:

Eric, our engines are tuned for 100% power. That’s where the problem is. What is an electronic fuel injection system and an electronic ignition system going to do to make more power without detonation? 
 

There is nothing they can do that we cannot do with what we have. We can adjust spark timing, we can adjust mixture. What else is there? 
 

I guess you could say they can get closer to detonation than we normally get, but how would we get there? Knock sensors have proven ineffective on aircraft engines. Ion current sensing may work. I mentioned it to George Braly once and he called me an idiot. But he was selling pressure sensing spark plugs. Pressure sensing spark plugs would work, but they are very expensive. 
 

So, what are the detonation margins for a certified aircraft engine? I don’t know the answer to that, do you? 
 

It seems to be in FAR 33 sub part D section 33.47 and AC 33.47.

Mercury outboard engines have a 12:1 compression and utilize a direct injections that is if i recall correctly 2000-3000psi.  There is available technology right now to solve this problem.

[N201MKTurbo]

6 minutes ago, Schllc said:

Mercury outboard engines have a 12:1 compression and utilize a direct injections that is if i recall correctly 2000-3000psi.  There is available technology right now to solve this problem.

You are comparing a marine engine that is liquid cooled with an unlimited source of cold water? While they both are similar because they run at a constant high power, beyond that they are quite different. The marine engines typically make full power at 4000 - 6000 RPM our engines are limited to 2700 RPM.

But that's not what we are talking about. We are talking about how to get our existing engines to run on unleaded fuel that doesn't dissolve our airplanes.

I don't think Lycoming or Continental would have any problem making a clean sheet engine that would run on 94UL and make whatever power you wanted. They would be a little bit heaver and a little bit less efficient.

[shawnd]

5 hours ago, exM20K said:

I enjoyed a Wankel in an early 80’s Rx7 but don’t think I’d want to fly behind one.

Imagine 231s and the need for perfect throttle control.  Every overboost means likely engine tear down and new apex seals! Yikes!  

[EricJ]

26 minutes ago, N201MKTurbo said:

Eric, our engines are tuned for 100% power. That’s where the problem is. What is an electronic fuel injection system and an electronic ignition system going to do to make more power without detonation? 

Tuning shops are always tuning engines for 100%  power, and usually increasing the 100% power level from the original rated power.   That's what they do and have been doing very effectively for decades.  And, yes, for 100% continuous power.   Usually the barrier is cooling to dissipate the increased heat, not detonation.

26 minutes ago, N201MKTurbo said:

There is nothing they can do that we cannot do with what we have. We can adjust spark timing, we can adjust mixture. What else is there? 

Timing and feedback.   Electronic injection allows better timing of fuel introduction.   There are lots of other things that are routinely done as well.  The bag of tricks is actually very big, including methanol injection, direct injection, etc., etc...much of which has been mentioned here already.    Some of these are what Lycoming added to the iE2 engines, and what they did was really only a basic step toward what is possible.   Once we do get unleaded fuel, O2 sensors will be possible to get even better feedback for finer adjustment.    Garmin panels like the G3X already have inputs for O2 sensors, since they're already used on experimentals.

26 minutes ago, N201MKTurbo said:

So, what are the detonation margins for a certified aircraft engine? I don’t know the answer to that, do you? 

There are lots of people beyond you and I that know how to do this and are already doing it, even on airplanes.   This isn't new or immature technology, it's just foreign to certificated aircraft because certification costs.

[Schllc]

1 hour ago, N201MKTurbo said:

I don't think Lycoming or Continental would have any problem making a clean sheet engine that would run on 94UL and make whatever power you wanted. They would be a little bit heaver and a little bit less efficient.

A clean sheet is exactly what i am talking about.  I have no doubt they could negotiate all of these problems relatively easier.

F1 Cars develop 1000hp with a 1.6 litre engine!  The tech is available to do this, the problem is the FAA makes it cost prohibitive.  Yes I realize a boat engine and an F1 engine are entirely different animals, but the hurdle is not physics, its an onerous approval process.

[GeeBee]

We already have people moaning and complaining about the cost of resealing fuel tanks. Wait until you tell them they have to buy a new engine to go unleaded.

[N201MKTurbo]

23 minutes ago, GeeBee said:

We already have people moaning and complaining about the cost of resealing fuel tanks. Wait until you tell them they have to buy a new engine to go unleaded.

And a new clean sheet EFI engine will far exceed the value of many of our airplanes.

And I’ll bet money there won’t be one available within the next 10 years.

[MikeOH]

1 hour ago, shawnd said:

Imagine 231s and the need for perfect throttle control.  Every overboost means likely engine tear down and new apex seals! Yikes!  

Yuup! BTDT, twice. Oh, and plan on new rotor housings...don't remind me why I know that!

[Schllc]

1 hour ago, GeeBee said:

We already have people moaning and complaining about the cost of resealing fuel tanks. Wait until you tell them they have to buy a new engine to go unleaded.

Wouldn’t this work the same way as cars?  Just phase them out, no need for a mandate. 
And yes, if someone tried to develop and get a new engine approved under current processes it would likely be 200k+. 
My point is that if the process for approval changed, there is no reason it would need to cost anywhere near that much. 

[Pinecone]

5 hours ago, Schllc said:

I don't believe this is true.  The mercury outboard engines developed high pressure injection, this would address the detonation issue.

Easy, water cooled.

My 2002 BMW M3 runs 11 to 1 compression ratio on pump gas that is not far from UL94.  Except it does perform better (more power) on higher octane fuel.

[A64Pilot]

6 hours ago, N201MKTurbo said:

The warbird guys have a lot of engines designed to run on 145 octane fuel. They are all happily flying along on 100LL with MP limitations.

Weighing thousands of lbs than their combat load too and probably a much reduced speed and climb rate, but we don’t have the excess power they do, and we can’t reduce the weight like they have done.

Essentially at sea level we would be reduced to the power output that those that live at 5,000 ft live with, but we would perform better because while engine power is down we still have higher air density, cruise at or above 5,000 ft there would be no difference.

Want to see what it would be like? T/O at 25” and adjust to maintain that until your full throttle. Yeah we could do it, but ever chart in the POH is invalid for T/O and below 5,000 ft.

Back to we non turbo folks won’t lose any power with ADI on 94UL. They say it works fir the turbo folks too, but I have no specifics on that.

 We could go to unleaded fuel tomorrow, but for some reason the emphasis is on wanting a magic fuel that I maintain we don’t know what it will cost. Or a replacement engine that I do know ballpark what that will cost, more than I paid for my J model. Every environmentally friendly fuel has cost more, back in the 70’s when first introduced UL car gas was much higher that’s why so many mis fueled their cars, and Diesel used to cost far less than gas, but ULSD came along in 2006 and it’s $1 a gl more than gasoline. So just taking the sulphur out of Diesel cost about $1.50 a gl.

Ever looked to see how much sulphur Jet has? What’s it going to cost to go to low sulphur jet?

There is I’m sure at least thousands of times mor Jet burned than 100LL.

94UL in widespread use should cost less than 100LL, but I bet it won’t but if it’s the same I can live with that.

I think in my opinion it’s become pretty clear that the GAMI fuel as currently formulated isn’t the answer that was hoped for, it could turn out far worse than the Mobil 1 oil problem.

Personally I’m astonished it’s still being sold, Cirrus has said they are concerned about the airworthiness of their aircraft that have used it, and the FAA usually listens to manufacturers. If a Cirrus suffers a structural failure there is going to be hell to pay, I know nothing about Cirrus but if it’s made like I think the tanks are part of the wing structure, if they get compromised, so is the wing.

But then I think if the current administration gets wind of what’s going on, we won’t have to worry about 100 LL going away for at least four years, beyond that? Who knows.

 

Edited February 20 by A64Pilot

[A64Pilot]

Average Jet a sulphur content is 400-800 PPM, max allowed for ULSD is 15 PPM

This study says it would only cost 5c a gl to reduce it to ULSD levels, so why does ULSD cost so much?

https://lae.mit.edu/2024/06/28/study-released-on-the-costs-and-benefits-of-desulfurizing-jet-fuel/

When are the Environmentalist wake up to the Sulphur content of Jet?

Why are they so concerned with 100LL? It’s a drop in the bucket.

[N201MKTurbo]

23 minutes ago, A64Pilot said:

Weighing thousands of lbs than their combat load too and probably a much reduced speed and climb rate, but we don’t have the excess power they do, and we can’t reduce the weight like they have done.

Essentially at sea level we would be reduced to the power output that those that live at 5,000 ft live with, but we would perform better because while engine power is down we still have higher air density, cruise at or above 5,000 ft there would be no difference.

Want to see what it would be like? T/O at 25” and adjust to maintain that until your full throttle. Yeah we could do it, but ever chart in the POH is invalid for T/O and below 5,000 ft.

Back to we non turbo folks won’t lose any power with ADI on 94UL. They say it works fir the turbo folks too, but I have no specifics on that.

 We could go to unleaded fuel tomorrow, but for some reason the emphasis is on wanting a magic fuel that I maintain we don’t know what it will cost. Or a replacement engine that I do know ballpark what that will cost, more than I paid for my J model. Every environmentally friendly fuel has cost more, back in the 70’s when first introduced UL car gas was much higher that’s why so many mis fueled their cars, and Diesel used to cost far less than gas, but ULSD came along in 2006 and it’s $1 a gl more than gasoline. So just taking the sulphur out of Diesel cost about $1.50 a gl.

Ever looked to see how much sulphur Jet has? What’s it going to cost to go to low sulphur jet?

94UL in widespread use should cost less than 100LL, but I bet it won’t but if it’s the same I can live with that.

I think in my opinion it’s become pretty clear that the GAMI fuel as currently formulated isn’t the answer that was hoped for, it could turn out far worse than the Mobil 1 oil problem.

Personally I’m astonished it’s still being sold, Cirrus has said they are concerned about the airworthiness of their aircraft that have used it, and the FAA usually listens to manufacturers. If a Cirrus suffers a structural failure there is going to be hell to pay, I know nothing about Cirrus but if it’s made like I think the tanks are part of the wing structure, if they get compromised, so is the wing.

But then I think if the current administration gets wind of what’s going on, we won’t have to worry about 100 LL going away for at least four years, beyond that? Who knows.

 

The main reason ULSD is so expensive isn’t completely because of sulphur.  With standard fractional distillation there are more heavy distillates than the lighter fractions. Such as gasoline. At the same time that ULSD was mandated, most refineries installed advanced catalytic crackers and reformers. After doing that, they can turn just about anything into gasoline. After these changes, diesel was no longer a waste product, but just another product. Because it has more carbons in it, it takes more of the feed stocks to make it. Therefore it now costs more.

[philiplane]

On 2/18/2025 at 11:44 PM, LANCECASPER said:

Around 2006 Mooney started a new process of sealing tanks, I believe using sealant on components as the tanks were being assembled rather than waiting until after to seal the tank.  I've heard that the long term results have proven much better. 

As a Service Center director, I was directly involved in repairing some brand new Mooneys in that time frame. The factory tried some new methods during assembly, and we had several 2005-2008 Mooneys with seeping tanks. Including brand new S Type Acclaims. Which did not go over well with the owners. Those planes went back to the factory for repairs and repainting.

Edited February 20 by philiplane

[Marc_B]

1 hour ago, philiplane said:

The factory tried some new methods during assembly, and we had several 2005-2008 Mooneys with seeping tanks. Including brand new S Type Acclaims

When you have bad technique or bad sealant you see issues relatively quickly.
 

But this is what irks me…when someone would point to the above and say “see, it’s all bad Mooney wet wings” and then point to a tank that’s lasted 25+ years. Then in the next breath point to experts in the field that have industry respect for their work with reseals and say “it’s so difficult to make it work only cottage shops can fix it”.

[A64Pilot]

10 hours ago, N201MKTurbo said:

The main reason ULSD is so expensive isn’t completely because of sulphur.  With standard fractional distillation there are more heavy distillates than the lighter fractions. Such as gasoline. At the same time that ULSD was mandated, most refineries installed advanced catalytic crackers and reformers. After doing that, they can turn just about anything into gasoline. After these changes, diesel was no longer a waste product, but just another product. Because it has more carbons in it, it takes more of the feed stocks to make it. Therefore it now costs more.

I’m sure your right, it just seems that over and over anything environmentally friendly is supposed to come at a minor cost and doesn’t or either isn’t actually environmentally friendly.

We switched to R-134A years ago to save the Ozone layer, but it turns out that now it’s supposedly extraordinarily bad as a green house gas, 1,430 times as bad as CO2

HFC-134a: a Potent Greenhouse Gas

• Most common refrigerant used in MVAC systems since the 1990s.
• Potent greenhouse gas with a global warming potential that is 1,430 times that of CO₂.
• Use of HFC-134a in MVAC systems accounts for an estimated 24% of total global HFC consumption. It is the most abundant HFC in the atmosphere.  
• The restriction of HFC-134a will occur under a broader prohibition of any substances with a Global Warming Potential (GWP) higher than 150 in the MVAC sector.
  • HFC-134a will no longer be allowed in nonroad vehicles as of January 1, 2028.
  • Servicing of existing vehicles using HFC-134a with HFC-134a will not be impacted and will continue to be allowed.

LED light bulbs it seems have arsenic and lead in them that makes them bad for the environment to throw them away

Are LED light bulbs dangerous?

Unlike other types of light bulbs, LED bulbs don’t contain mercury, but they do have small amounts of other hazardous substances such as arsenic and lead. Therefore, if you dispose of them with your regular household waste, these toxins can leach into the environment and make their way into the water table, so it’s important to dispose of them properly.

It just seems to me that many things the Environmentalist cry that we must do to save the Earth it seems to be just as bad or often worse, and always seems to come with a special Environmental Tax.