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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'>I should add that yes, as Bob Spidell stated, there’s no actual thing as “aviation unleaded” but at least theoretically the fuel suppliers control RVP, etc to the ASTM specs required by the FAA-issued STC’s for aircraft use. In fact, the refineries and distributors are supposed to maintain specific trucks only to deliver car gas for aircraft use to avoid any cross-contamination. It carries no road tax (a huge part of car gas prices) but the cost of the separate refinery streams and distribution costs still price it well over a buck a gallon more than car gas at a nearby gas station. Our airport sells mogas for $4.30 per gallon. Costco had 93 octane for $3.30 the other day.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'>In my limited experience our airport’s car gas has been very consistent. But I don’t have an auto gas STC for my present plane because 100 LL works fine for me and there’s little price difference. And I’m sure that 100 LL is pretty consistent across the country. Not too sure what I’d get out of a mogas pump at some unfamiliar airport.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'>As they say, YMMV<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Karl Vacek [mailto:Stearman809@GMail.com] <br><b>Sent:</b> Monday, August 26, 2019 12:22 PM<br><b>To:</b> shop-talk@autox.team.net<br><b>Subject:</b> RE: [Shop-talk] Electric String Trimmers<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'>The gas I buy at the airport for my lawn equipment is indeed aviation unleaded. In the early 1980’s the EAA ran a project to prove that low-compression aircraft engines could safely run on unleaded car gas. Peterson Aviation in Nebraska did a similar project. Both sell STC’s to allow use of that specific fuel in applicable aircraft. Basically a permit to allow the use of unleaded auto fuel a specific in aircraft under specified conditions.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'>The wide marketing of gasohol soon after the STC’s became available caused issues – the FAA permission is ONLY for straight unleaded – no alcohol. Here in the Peoples Republic of Illinois the corn lobby has us inundated with gasohol, and there are only a handful of places in the state where you can fill up a car or truck with ethanol-free car gas.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'>For use in those planes so certificated, many airports now carry “aviation mogas” – regular unleaded without alcohol. It’s not to be sold for on-road vehicles, just planes. And airports can legally pump it into cans for small-engine use.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'>I have plenty of the blue stuff (100 LL) in the Stearman, but haven’t ever put it in any lawn equipment. Almost the same price, so that’s not the issue, but my lawn equipment just doesn’t need lead. Even my 3-wheel Harley (well, it’s a 2-cycle Harley Davidson golf cart) uses unleaded just fine.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'>Used to be better to use 80 octane (red) but that’s pretty much gone today. That was good for mowers, etc. too. As noted, 100 LL has 4x the lead of old 80 octane, so lead fouling can be an issue in aircraft engines. Some guys who have the auto fuel STC even run 75% auto gas and 25% 100 LL to simulate old 80 octane. When 80 octane went away and 80 octane engines that to switch to 100 LL, many pilots experienced lead-fouling issues, and many top overhauls were done. Sometimes guys lapped the guides with the cylinder in place too. But that’s largely over now, as most engines have appropriate valves and guides to allow regular use of 100 LL. Personally I’ve not had an issue with 100 LL in my engine, which has stock WWII era valves and guides, and I have indeed had occasion to pull three cylinders over the years and disassemble the valves, with no lead fouling issues present.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'>As far as purple gas being available at Warbird events, I’ve not ever seen it, but my Stearman is at the lower end of the Warbird spectrum. We do have a Grumman TBM Avenger on the field, and Tom uses 100 LL in that – it’s got a Wright 2600-20 (1900 HP). And P-51’s regularly fill up with 100 LL. Maybe the purple stuff is available sometimes, but not commonly, and as far as I know most Warbird engines run fine on 100 LL.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'>One of the things that allowed higher boost pressures during WWII was water injection. That’s still an option.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'>Thanks !!<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'>Karl<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546A'><o:p> </o:p></span></p><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>Subject:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Re: [Shop-talk] Electric String Trimmers<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Keep in mind that Low Lead Avgas, like 100LL, still has 4x the amount of lead that standard automotive gas contained. The guys who run this stuff in race cars and the like often report issues with lead deposits on valve stems and seats. I have personally see a valve stem so leaded up that it stuck open. Use at your own risk.<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'><p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:12.0pt;margin-left:11.4pt'><br>It was probably blue, and it was probably 100LL. Half the lead of most <br>of the earlier grades, most everyone's pretty much still standardized on <br>this.<br><br>Some places and applications (warbird events?) you may find more heavily <br>leaded super-sauce for your high-boost blown motors. The reason the <br>Merlin went from 800HP to 1700+HP in production was all that sweet, <br>sweet American leaded 130-octane gasoline.<br><br>John<o:p></o:p></p></blockquote></div><div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>