Shadrach

I hope not. A later model 2900lb, 201 is already near the year round limit of what’s practical from power to payload ratio. I recently flew to Niagara with my plane full of family, bags and 50gals of fuel. OAT of 94° and a departure DA of ~3000’ at 300msl. It reminded me of why I rarely fly in the dog days of summer…It turns my airplane into a dog. I don’t want to give up any power.

And yet there are only a handful of modern spark ignition engines that will match our dinosaurs in terms of BSFC.

As far as I can tell you have done zero research on the one replacement that has been through the STC process (twice) and has currently been flying in multiple GA aircraft (both turbo and NA) for several years and hundreds if not 1000s of hours. You don’t appear to know anything about the supplemental type certificate or the process that went into approving the fuel. Why do the home work or better yet actually engage the developer when you just “know” generally speaking based on your expertise that GAMI is holding back and or obscuring the negative aspects of this fuel. So yeah, you are throwing rocks from the cheap seats as you’ve not articulated a single specific area of concern. Speaking of which, I do have a concern regarding G100UL but it has nothing to do with functionality. It has to do with how it might interact with well preserved, acrylic enamel paint on vintage birds.

George has openly stated that G100UL started with a high octane, unleaded formulation that I believe was experimented with in the early 40s but was not fully developed because at the time, TEL was easier, cheaper and more practical. Much of GAMI/APS/TAT’s successes have come from modernizing and implementing what was well understood 80-90 years ago.

Firstly, the CR for your IO360 is 8.7:1 not 8.5:1 I’m not going to do a real deep dive into the specs of the 5L Ford V8, but there are a number of factors at play. The shape and size of the combustion chamber as well as the stroke (piston speed) all have an effect on detonation margins. The combustion chamber for the 302 is less than half that of an IO360 and it is liquid cooled. Furthermore, it has variable ignition timing and while I have not looked at the timing map for the early 302, I would bet that at 2500 RPM it’s more conservatively timed than the IO360. No one runs a car the way that we run our aero-engines, to do so would require using gear ratio to limit speed for a given throttle setting…ostensibly selecting the highest gear possible that allows the engine to just maintain the desired speed

There is nothing exact in his statement… It is non-specific, philosophical speculation being thrown from the cheap seats. There is no substantive argument. Its all feelings…Oddly emotional for an engineer…

It’s not a chemical engineering miracle, have you bothered to look at the MSDS? What would you have done if you were 3 years into an STC application when a Collective of alphabet bureaucracies, developers and general aviation “stakeholders” started an initiative to develop a replacement fuel but provided no method of consideration for the testing and certificationh work you had done up to that point? Would you have abandoned your previous efforts and started over? Can you site a specific example of where the STC process is less rigorous than PAFI/EAGLE program? Can you site one parameter where G100UL falls short of ASTM D910 specifications other than the absence of TEL? I am always open to alternative views based on evidence, data or even under certain circumstances unsubstantiated rumors. However, you’re not doing any of that, you’re throwing philosophical rocks from the cheap seats with no actual evidence. No one is asking you to beta test or buy anything…yet…when/if that happens, it will likely start with your state and the Fed will follow. Also, it’s pretty clear that you’ve not read the FAQ section of the G100UL website. You may think it is biased or contains lies by omission. Either way, with your engineering background, you may find some actual bones to pick that would help to steel-man your argument which up to this point seems to be limited to “it’s to good to be true so it’s not”. I’m here for it and would love to see well fleshed out contradictory opinions rather than just contrarian comments for the sake of contrarian comments and pejoratives.

I respectfully disagree. I’ve worked with many “salesman” in my life. Having a personal and financial interest in a product that you’ve developed and being a salesman is not the same thing. Sales is a skill in which the product is fungible. Does referring to someone as an “attorney” without mention of their additional and relevant qualifications strike you as a “reminder” made in good faith? If George was “essentially a salesman” then GAMI wouldn’t be turning away Lycoming operators with conforming engines that have good cylinder to cylinder air fuel ratios. They’d instead be claiming some unmeasurable benefit like superior atomization to push as many tuned injectors into the market as possible. From Finewire plugs to speed mods to new prop designs, etc…the aftermarket is full of products with claims that offer little to no supporting published data. George presents a granular analysis with raw data collected using a very sophisticated test stand that demonstrates a repeatable result that is consistent with the results of the failed UND trial…and our biggest takeaway from that should be to remember that he is “essentially a salesman” and an “attorney”? Seems like there’s an axe to grind.

With stock pistons? Are you running a turbo?

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.

How is E85 relevant to aviation? At 73% of the energy density of avgas by volume it does not seem like a viable option for low compression (relatively speaking), naturally aspirated engines, even with variable ignition timing. 100LL = 120,200 BTU per gallon E85 = 88,358 BTU per gallon.

BDS is real… I don’t think 100LL is a significant environmental issue. However, the writing is on the wall… 100LL’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). It’s not GAMI’s fault that they have what appears to be the only currently viable “drop in” thus far. 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. Why else would he bother to go through the STC certification process twice rather than work within the PAFI framework. Good for him for going his own way. He still has a tough row to hoe. I won’t be buying an STC unless/until G100UL is readily available in my geographic area. Do remember that any company that crossed the finish line 1st would be in GAMI’s situation. It’s not like some dark, insidious force is pushing for their monopoly. It’s simply a function of a small, agile, firm grabbing the ring first. I’m all for competition. Unfortunately, UL94 clearly has issues…unless you think George Braly and his evil minions sabotaged the UND trial. Given that 94 UL has failed to meet expectations. I’m pretty dubious that they’re going to get to 100 in the near future. Being that you’re in “Kalifornia”, as you’re fond of saying, I hope you have alternative plans for your airplane because there’s more pressure in your area than anywhere else in the country to prevent you from purchasing 100LL. It’s odd that you have no gratitude for the fact that someone has actually taken the risk, effort, investment and time required to develop an unleaded Aviation fuel that is likely turnkey in your current aircraft and also feel compelled to call those that do have gratitude, “fanboys”…

100LL is still readily available in most states. There is no benefit to be gained by the engine manufacturers to enter the fray. As I understand it most aero engines were certified to run on fuels that meet a specific ASTM standard. In most cases, those standards specify TEL as an antiknock. this means the engines must either recertify to a new ASTM standard that does not contain TEL but meets minimum octane requirements (does not currently exist ) or the fuel must be approved through STC. It’s not so simple as an engine manufacturer endorsing a fuel producer.

indeed a consequence of having the tech to see the big picture is being able to see odd controller decisions play out in real time. Or in the case of Potomac Tracon, apathy and needless denials of reasonable requests from GA piston recips.

only the parallel valve IO360s are 8.5:1. The angle valve engines are 8.7:1. The UND fleet was running peak EGT, perhaps to keep things consistent with how they were running 100LL prior to the test.

Most of those questions have been addressed over the last several years which you’ll find if you do a deep dive into what has been written and presented. You keep referring to him as “this guy”. George and his colleagues (RIP Walt and John) have done more to educate pilots on the inner workings of reciprocating aero engines and the nuances of the combustion science associated with them than anyone in the industry. If anything, Lycoming has been a hindrance to those efforts, but they have come along after embarrassing themselves in writing. At this time, the engine manufacturers have no incentive to endorse a specific fuel. And indeed I would be suspect of such an endorsement. George Braly would probably answer all of your questions directly if you emailed him. Be sure to start off the email with “Dear this guy”…

CHT redline could be used as a parameter for retarding timing on an emag. Another option would be rate based above a certain number; something like 2°/ second at or above 400°. Could easily have an annunciator that shows when the mag is retarded and a push to cancel. Not as sophisticated as a knock sensor but adequate to save the engine if the pilot is too busy to save it.

As far as I know all current E-mags offer timing advance beyond the TCDS specified fixed ignition timing. None that I know of offer retarded timing other than at start up. I suppose CHT could be used as a parameter for retarding the timing.

That is their reputation, but as an occasional user of that airspace, I have found NYC area controllers to be far more accommodating and professional towards GA compared to other busy sectors.

5° is certainly enough to be the difference between detonating and not detonating. The timing discussion is a funny one. People often say there’s no significant difference. This begs the question, then why bother to retard the timing? The truth is somewhere in the middle. It’s noticeable but more-so when at the edges of the performance envelope. My plane is timed to 25°; climbing on a single mag (good approximation of 5° of retard) certainly makes a difference, especially this time of year.

Might run fine with just a few quarts, but this time of year I think oil temp would be significantly elevated…which increases the burn rate…which would be sub optimal when starting with just a few quarts.

His wife is the one who was likely terrified. He seemed oddly calm for some one who could not set up his panel gps and had just unexpectedly run a tank dry.

Two different flights. This one terminated at KBDR the other thread was at KMRB.

I’ve read a lot of P&Ls. I’ve also read lots of engine data graphs. I think the analogy sub optimal. There are lots of line items on a P&L that can be massaged depending on whether your goal is minimizing or maximizing profit. George showed a granular presentation of a short term engine run, complete with graphic depictions of multiple fuels (G100UL, 100LL, and 94UL) running back to back without shutting down and with no other changes to the operating parameters. If you believe he has a sophisticated engine test stand and knows how to use it (which I do), it is difficult to imagine the results are biased even though George might be. The UND test was halted because it damaged cylinders. GAMI wouldn’t be testing this fuel if it weren’t for the failure of the trial. I suspect George knew what happened and was all too happy to showcase it. That doesn’t mean his data is wrong or has been cooked. He is merely taking an opportunity to showcase his competitor’s failures.

Hi Charles, If you are looking to rehome your old hydraulic components after the conversion, please reach out.