I believe the European octane ratings are Research Method only, which reads 3-5
points higher than US (R+M)/2. So, European 98 octane would be equivalent to US
93 octane (rare, but available in some areas in the States; 100-octane is
available for boat engines around Havasu).
Contrary to popular belief, ethanol can actually raise octane. There's a gas
station in Los Altos that used to sell 95-octane, which was E10 IIRC. It's very
difficult to raise the octane rating of pure gas--it requires special
refining--that's why TEL was added starting around WWII for high-compression
fighter engines (it was 'discovered' at the Sloan-Kettering institute, who
tested several thousand compounds before settling on TEL). Adding ethanol to
gasoline means the gas part doesn't have to be as carefully refined (hence
'cheaper'). There is an exhaustive research program being undertaken in order
to develop an aviation fuel to replace 100LL--100-octane, 'low-lead,' which I
believe is 'only' 2 grams/gallon of elemental lead vs. 3 grams/gallon of
previous formulations--and it is proceeding very slowly due to its complexity.
I've run tanks of E10 and tanks of pure gas, and didn't notice any significant
variance in mileage, but it's usually an 'oranges-to-apples' comparison since
most runs involve a mix of highway/freeway and grades, stop-and-go, etc.
----- Original Message -----
From: "John Spaur" <jmsdarch at sbcglobal.net>
To: josef-eckert at t-online.de, "Oudesluys" <coudesluijs at chello.nl>,
"Forum' 'Healeys" <Healeys at autox.team.net>
Sent: Thursday, January 26, 2017 10:54:48 PM
Subject: Re: [Healeys] Ethanol
Wish I could get 93 octane let alone 95 or 98!
John
San Jose, CA
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