Date:         Thu, 20 May 1999 20:29:38 EDT
Reply-To:     Vantaztik@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Roger&Zoe Ann Banker <Vantaztik@AOL.COM>
Subject:      Re: How do anti-ping additives work?
Comments: To: synergx@ibm.net
Content-Type: text/plain; charset="us-ascii"

In a message dated 5/20/99 9:45:50 AM Pacific Daylight Time, synergx@IBM.NET
writes:

> >I am trying to figure out if anti-ping additives merely slow
>  >the burn rate of the fuel-air mixture or actually just increase
>  >the charges' resistance to detonation (and if it does the latter,
>  >how does it accomplish this).

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