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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#467886" vlink="#96607D" style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt'>Michael, for what it’s worth, I’ve ignored all warnings and online threads talking about detonation and engine wear and simply used standard Tier 1 91 octane pump premium with ethanol at Denver’s altitude for years. I dislike the hassle (and occasional clothing disaster) of diddling with octane boosters and fuel additives. Even in engines with cylinder heads milled to raise compression to a true 10.4:1 range, detonation and wear have not been issues. I can’t comment on a turbo engine at this point, but I’m thinking of tossing a turbo onto a set of 10.4:1 compression 140 big-valve heads to see how long it takes to melt the piston tops. If I do that and ethanol helps with piston top life, I’ll let you know!<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Eric S.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> RMC-List <rmc-list-bounces@corvair.org> <b>On Behalf Of </b>Michael Brittan via RMC-List<br><b>Sent:</b> Friday, April 24, 2026 1:47 PM<br><b>To:</b> rmc-list@corvair.org<br><b>Subject:</b> RMC List - Octane boost question<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Hello All,<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I like to use only non-ethanol gas in my cars (Spyder and 2x164/110 Monzas). 87 non-ethanol is available in my area of SE Denver at a reasonable price. Preferred 91 octane non-ethanol is available at the Mobil station in Lakewood, but at a huge price premium and a 30-mile round-trip (+- 2 gals of gas consumption right there) from my home.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I can eliminate the pre-ignition with expensive octane booster containing MMT. Cheaper brands contain alcohols, so defeat the purpose of using no-ethanol gas and don't raise the octane as much per ounce of dosage.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I'd welcome members' views on using such octane boosters and whether they may have preferred brands. Could any harmful side-effects be experienced with our trusty Corvair engines using these boosters? What do members feel about using standard pump 91 octane containing ethanol?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Best,<o:p></o:p></p></div><div><p class=MsoNormal>Michael<o:p></o:p></p></div></div></div></body></html>