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Subject: Re: [FlyRotary] Re: Pport/cold side injectors
From: Ernest Christley <echristl@cisco.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Date: Fri, 21 Jan 2005 11:04:44 -0500
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On Fri, 2005-01-21 at 10:23, Ed Anderson wrote:
> Wow! Ok, Ernest
> 
> Certainly sounds plausible that long runners would contribute to the
> separation of the wheat and chaff.  I wish I could remember what my
> professors taught me in those long ago days. Perhaps if I had day dreamed
> less and studied harder......Nah!!!
> 

I took only one other thing away from that class.

What has LEAD got to do with octane?  It's a metal.  It doesn't burn. 
Why would anyone put it in their gas?

Well, it turns out, the light (less carbons per chain) molecules are
easier to atomize (convert to a semi-gaseous state by spraying through a
small orifice).  If you want a nice compact carberator/intake system,
you need lots of those short chains.  The down side is, those short
chains don't have a lot of energy and tend to want to burn on there on
when exposed to the pressure inside a cylinder.  What you want is
something that will atomize like the short chain, but burn smoothly like
the medium length ones.

Enter LEAD, stage right.

Lead has four bonding points.  Mix some with your gas, and each lead
atom will attach to one end of 4 different carbon chains.  Remember, the
chain only burns when the end is exposed to oxygen?  Well, now one end
is locked down.  If the fuel started out as pure mixture of 4 carbon
chains, and you mixed just the right amount of lead, you'll end up with
a batch of molecules shaped like a plus sign (+).  Each arm of the plus
will be 4 chains long.  The oxygen can only get at the ends, so this
mixture will burn like 100 Octane (ie, 100% Octane).

And my last point.  Higher octane is not always better.  High octane is
good for turbo applications, because is has a slower burn rate.  But you
want the burn to occur so that the maximum pressure is in the chamber at
the highest torque point of the cylinder/rotor rotation.  Not before and
not after.  If you're running exceedingly high RPM in a non-turbo
application, LOWER octane may actually produce more power.  In this
situation, the higher octane stuff may still be burning well into the
exhaust cylce.

Now, I'm done.  My brain is empty.