A&P IA CMEL here:
RE: the angle valve engine octane requirements vs parallel with just slightly higher CR.
Angle valve engines have greater volumetric efficiency than Lycoming parallel valve engines. They actually bring in just over 10% more air, so even if the CR were the same, detonation margin would be reduced. You could think of it this way: It would be similar to a parallel valve engine with 9.5:1 CR. This is one reason ideal ignition timing on the Lycoming angle valve engines is 20 degrees. There is no practical way to reduce ignition timing below 20 or so, to allow a lower octane fuel without negatively affecting performance.
RE: UL94
This is a great fuel, for engines designed to run 91/96 or lower octane fuels. It should be required at all airports, on a ramp with reasonable transient parking, and easy access to ground transportation. The FAA should create this plan, and allow a single low bidder to implement it at all GA airports that signed up for FAA funds. As far as the land lease, I suggest that the FEDS just condemn the necessary area, and TAKE it. NO local airport authority 10 Mil liability coverage BS. This would cost under 40K per airport to implement. Let the FBOs fight over the 100 octane stuff. (it should immediately be required to meet 100VLL spec.) The big thing is that high volume flight training could stop dumping lead very quickly. It will be better for everyone. No students in 172s maneuvering among the G5s at KPMB. In the late 80s, I had aircraft in flight schools and used autogas. Ethanol was not common added back then. FBO's and local governments, + ethanol mandates have colluded to make it difficult for any method other than the one suggested here, to get the lead out now. Just in case you do not know, the lead issue approaches that of FLINT. https://www.nbcbayarea.com/news/local/children-near-reid-hillview-airport-experience-lead-poisoning-new-study-reveals/2623245/
RE: Water/Methanol injection
There is very serious research on this, done by airlines after world war 2. Here is one source. https://www.sae.org/publications/technical-papers/content/460192/ basically this remedy is worth 12 points of octane! It actually is the answer, combined with UL94 or Hjelmco's 91/96 https://www.avweb.com/features/the-return-of-anti-detonation-water-injection-adi/ NOTE: UL94 is made to a new ASTM standard D7547; that allows all lead to be removed, where Hjelmco has a tiny bit of lead to meet ASTM D910. https://www.hjelmco.com/pages.asp?r_id=13963 Search FAA SAIB: HQ-16-05R1.
The airlines were using Grade 80 with water methanol on supercharged engines. Total liquid consumed was equivalent, with water displacing AVGAS. More power can be obtained using water methanol injection with 87 octane, than 100 octane with enrichment only, so it is possible to get the same power on a lower octane fuel, and MORE power on supercharged engines.
The actual cost to manufacture a Water Methanol system similar to https://www.flyinpulse.com/ should not be more than $900.00. WATER alone is better than Water Ethanol, but Water Methanol produces more total power than water alone. How much water?? wwiiaircraftperformance.org › p-47 › P-47_Water-Injection_3feb44.pdf 2.1 gal per minute @ 2500HP.
Thanks for listening.
John Schreiber
