Sender: <marv@lancaironline.net> (Marvin Kaye)
To: flyrotary
Date: Sat, 29 Mar 2003 15:02:08 -0500
Message-ID: <redirect-2092056@logan.com>
From: <rogersda@cox.net>
Subject: pre-ignition/detonation (was: Spark Plugs)
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit


Al Gietzen <alventures@email.msn.com> wrote:
 
>> The rotary can survive a little detonation, but won't take much 
>> preignition. 
>> 
>> Lynn E. Hanover      
 
> OK, Lynn; now you've done it.  I understand that concepts that
> preignition is ignition of the compressed fuel/mixture prior to the
> normal ignition by the spark, caused by some hot spot or something; and
> detonation is a sort of flash, or spontaneous combustion ahead, or away
> from, the normal flame front caused sonic compression waves, or
> whatever.  How can you tell the difference?  And what causes one or the
> other? And does one lead to the other?  When the piston engine in my car
> "pings" because the timing is too early or the octane is too low, which
> is it.  I've never heard preignition or detonation in a rotary, but if I
> ever do, now I'm going to want to know which it is.
> 

   I'm not Lynn, but detonation does not change the effective timing, only the pressure curve.  As long as the tangent of the rotor has passed over_center before the pressure reaches a certain point, damage is unlikely.

   Pre-ignition, on the other hand, acts just like advancing the timing.  Considering the geometry of the rotary chamber, it's probably far harder on a rotary engine than on a reciprocating piston engine.

Regards,
Dale