Turbo header design

[Aaron Willis]

EFISYSTEMS at aol.com wrote:
> 
> I am interested in this thread as I would like to understand better the
> dynamics of a turbocharged engine.  It was always my understanding that the
> reason for a header over a manifold (in a turbo application)was to equalize
> the pressures at the ports,,,not for any kind of scavenging effect because
> there is pressure in the exhaust before the turbo usually equalling the intake
> pressure(I'm not concerned with how fast the turbo spools up at this point of
> the thread,,,, only with what is happening at full boost)  I guess my question
> is how could there possibly be scavenging if the exhaust has 15lbs of
> backpressure(for a number)???????Greg???Anyone???
> -Carl Summers
> 
<SNIP>
   Keep in mind that even a NA engine always has at least atmospheric
pressure on the exhaust (and on the intake as well, at WOT) which is
around 15psi at sea level.
   Perhaps the key is in pressure differential between cylinders and
exhasut systems?  Just a guess...

Aaron

ICQ # 27386985