Re: Anti-reversionary step - how does it work?

["Bruce Bell" <bbell04@ibm.net>]

> From: Graydon D. Stuckey <graydon@apollo.kettering.edu>
> 
> On Mon, 8 Jun 1998, Kevin Ford wrote:

> I don't see this happening very much at all in a turbo because the cam 
> reduces overlap to a very low level.  Does anyone have the exact number 
> of degrees of overlap on the turbo cam?

The AAN (S4) has no overlap. 

> 
> > A reflected pulse (echo) will not scavenge, it will impede the fresh 
> > charge's progress into the cylinder.  The antireversionary step will 
> > help lessen the reflected pulse, thus lessen the impedence on the fresh

> > charge's entry into the cylinder.  

I found the following
at:<http://diane.island.net/~rpmres/index_html/drivingtopics.htm>

"Passage design has a greatest impact on the engines ability to produce
high torque levels with the RPM curve of an engine. Torque will be reduced
due
to pumping losses or gained because of a design that encouraged wave forms
to occur. Header tubes have wave forms travelling up and down the tube
during exhaust cycles. 

The most important event is during the return of the wave form to the
exhaust port. This will create a negative pressure at the exhaust port,
scavenging the remaining combustion gas from the cylinder. At the same time
the intake valve is open, intake gasses are drawn in to the cylinder. The
same wave forms are occurring with the intake tract assisting this
process."