Date:         Fri, 21 May 1999 08:18:42 -1000
Reply-To:     Leif <lpaulsen@CMCFLEX.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Leif <lpaulsen@CMCFLEX.COM>
Subject:      What Octane Fuel is best?  [was RE: How do anti-ping additives
              work?]
Comments: To: Vantaztik@AOL.COM
In-Reply-To:  <55ccb161.247602f2@aol.com>
Content-Type: text/plain; charset="iso-8859-1"

I Don't have the post that started this thread so maybe this is a redundant
question.  Which octane rating is best to use in our vans.  I realize the
opinions are probably varied on this so lets all be civil.  I promise I
won't sue any of you for the damage your recommendation may cause. (remember
it's friday) LOL.

Leif Paulsen
'86 Syncro "4BY-THOR"


> Hi all, glad to see the list is back up.  I missed the original anti-ping
> posting, so please pardon me if I am repeating someone's reply.
> I was taught
> that anti-ping additives work by raising the octane rating, thus
> making the
> fuel more difficult to ignite.  The higher the octane, the more heat and
> pressure are required to ignite it.  Pinging, or pre-detonation,
> is when the
> fuel/air mixture self-ignites from the heat and pressure, before
> the spark is
> supplied (dieseling).  The higher the compression and greater the
> heat, the
> greater the danger of pre-detonation.  When there is pre-ignition
> long before
> the piston has risen towards the top of its stroke, the piston
> has to fight
> its way up against tremendous pressure.  This puts tremendous
> strain on the
> engine, and builds very high heat.  Pinging is a quick engine killer.
> Antiknock sensors retard the ignition, reducing the heat in the combustion
> chamber, thereby making it harder for the fuel to self-ignite on
> subsequent
> revolutions.  Antiknock sensors help, but when you run low octane
> fuel in a
> high compression engine, even with an antiknock sensor, you are risking
> severely shortening the life of your engine.
> Zoe Ann & Roger
> 1987 Adventurewagen 4x5
>