One of those stories spread around the LBC campfire in the early 80s when
leaded was being phased out was that mixing high octane unleaded with a bit
of leaded would supposedly result in a higher overall effective octane
rating.
And yes, av gas 100 octane "low lead" does have a higher lead content than
the pump gas in the late '60s and the currently available leaded racing
fuels. Av gas is "low lead" compared to whatever was used back waay back
when. I'm guessing WWII era.
Of course, in order to get av gas these days you typically need to have a
plane. Or a friend willing to siphon a few gallons from his tank for you.
As to lead and engines, another campfire story is that a dose of lead every
once in a while is enough to leave a coating on the head-valve area. Back
when leaded gas was the norm, the gasoline had a phosphorus compound added
to help dissolve the lead deposits in the cylinders. Hence the stickers on
unleaded gas pumps saying the fuel does not contain lead or phosphorus.
Unleaded gas shouldn't have such additives.. The question is whether the
heat of combustion will melt off any residual lead.
Originally TEL was added to gasoline to raise the octane rating because the
refineries at the time weren't designed for more complicated processes.
Chemistry has improved since then.
As to trying to mix up your own leaded... Where do you even buy TEL these
days? It's bad enough trying to buy batteries for the cars.
And at the most basic level... What percentage of your weekend race expense
is for leaded racing fuel?
And how bad is the valve recession on the engine you're running? Or just
nervous?
Cheers,
Jim
Dallas
'61 Morris Mini with full bore 1275S drivetrain and 105 octane leaded
'76 DM Spitfire.. Running unleaded pump gas
-----Original Message-----
From: vintage-race-bounces@autox.team.net
[mailto:vintage-race-bounces@autox.team.net] On Behalf Of Carl McLelland
Sent: Monday, April 12, 2010 4:26 PM
To: Ralph Steinberg; John.Desantis@Inficon.com; vintage-race@autox.team.net
Subject: Re: [Vintage-race] 110 octane race gas
I think you'll find, pending an actual qualitative analysis that 100 octane
"Low Lead" aviation fuel contains more lead than even Sunoco 110 leaded.
Carl
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