-------------- Original message from "George Lendich" <lendich@optusnet.com.au>: --------------


> Ernest,
> Let me try again.
> The leading edge is already radiused or sloped to enhance flow into the
> exhaust port, Lynn has suggested a further streamlining of that edge helps
> evacuate the exhaust.
> The top ( following) square edge helps to block the exhaust from entering
> the inlet area.
> Now the suggestion to me was to slightly radius this top edge.
> My thinking it would help draw in some inlet charge and that's not so good.
> However he has said he gets good performance from doing that mod.
> I'm unsure !?
> George ( down under)
> > George Lendich wrote:
> >
> > >
> > > It would also seem that if you radiused the following edge of the
> > > exhaust outlet, it provides better exhaust flow and less contamination
> > > of the inlet charge at idle.
> > > For your digestion!
> >
> >
> > OK. I'm about done digesting, so...
> >
> > This is completely logical, under the theory that the sharp edge will
> > trip the exiting airflow into turbulence. Clean air always flows
> > faster. I keep thinking about the exhaust inserts. Ed has the opinion
> > that they must be eating up horses to give the noise reduction by
> > causing back pressure. But what if the inserts work like a fowler flaps
> > and just helps the gas to exit is an orderly manner vs all turbulated?
> > Aren't laminar flow aircraft typically quieter than turbulent flow ones?
> >
> > Has anyone compared the noise produced before and after an exhaust has
> > been radiused?
> > Has anyone attempted to 'shape' the inserts so that it has a radiused
> > leading edge and a tapered trailing edge (ie, aerodynamic)? I know
> > they're not very thick, but their thickness is a significant portion of
> > the overal exhaust ports size.