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Re: Ignition timing

To: "Float-by Shooter" <>,
Subject: Re: Ignition timing
From: "Mike Gigante" <>
Date: Fri, 27 Aug 1999 11:52:38 +1000
Well, I have used avgas in both my race and rally cars. The race
car needs it (13:1), but the rally car doesn't (9.8:1).

These motors get pulled down on average once per year or so.
If there was a problem caused by avgas, I'd know about it.

On the contrary, since switching to avgas in the rally motor, the
chambers, valves and piston crowns are much cleaner than
when they ran on pump fuel. Just a light greyish tinge (a bit
brownish on the exhaust valves).

I won't be going back to pump fuel until I am forced to.


----- Original Message -----
From: Float-by Shooter <>
To: MG Board <>
Sent: Friday, 27 August 1999 11:36
Subject: Re: Ignition timing

> On Thu, 26 Aug 1999, Larry Colen wrote:
> I hear it said all the time that avgas is not good for ground
> applications, but I have yet to hear a satisfactory answer for why this is
> true.  My brother had to drain his airplane tanks a couple years ago when
> disassembling it, and he put the avgas into his OCP (old chevy pickup).
> Claimed that it ran better than ever before.  That is probably also a
> commentary on the quality of our automotive fuel here in Cordova, AK.
> > The reason that avgas is a BadIdea (tm) is that it has a lot of
> > in it so that it will work at a wide range of altitudes and
> > The effect of this is that:
> >  1) it is not optimized for near sealevel at reasonable temperatures,
> > as autogas is and
> One of the more common light plane accident patterns involves misjudging
> the amount of power/lift available for takeoff vs. available runway
> length.  I am quite certain that if avgas was truely not optimized for
> maximum performance at sea level and word got out, there would be an
> uproar over this in the aviation community.
> >  2) the additives do nasty things to rubber and plastic parts in your
> > fuel system, unless they are TrickAviationParts (read:$$$$) that are
> > specially designed to not disolve in AvGas.
> Since I am building my own aircraft, I have researched fuel compatibility
> issues somewhat and my findings have been opposite yours.  There have been
> a number of problems with the additives in autogas wreaking havoc on some
> aircraft fuel system, most notably composite fuel tanks.  It's been awhile
> but I think I read about this at the canard aviators website, at
> AFAIK, the most notable attitives in avgas are stabilizors to keep the
> fuel from going bad if it sits in the tanks for a while, and lead.  If you
> have a modern vehicle with an oxygen sensor you should NOT use avgas since
> it will foul the sensor.
> > > could go to a racing fuel
> > > or octane booster.  Note that aviation fuel will not work
> I have been told that 100LL avgas averages about 103-104 octane, if you
> need more than that you will have to get a special racing fuel.
> But don't take my word for it, do some research on the issue for yourself.
> Just my opinion as a low-time private pilot.
> ======================================
> Del Rawlins--
> "I'd like to find your inner child and
> kick its little ass"  --The Eagles

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