4-stroke carbon pipe design Q's

[Bob Kane]

I don't have the tools to directly measure the
parameters of a DZ cam, but I did install one in a
modified FZ case and I can tell you it does not
provide any real world performance improvement over
the FZ/L cam. The DZ cam has larger lobes, but the
base diameter is larger also so my guess is the lift
and timing are the same as the FZ/L cam. The increased
lobe size is to take the additional load of driving
the injector pump. 

So, the good news is whatever works for a DZ should
also be good for the FZ and L series.

--- Lance Van Nostrand <patterndude at comcast.net>
wrote:
> I want to thank everyone that replied with
> information.  I have a much 
> better idea of what to try to make something that
> will give best 
> performance.  I had already figured that we would
> want to avoid matching the 
> reflected wave and instead would want a pipe that
> was "long" so it would 
> help scavange.  Now I can see several benefits of
> this:
> 1. helps draw in new charge during overlap
> 2. reduces blowback diring overlap.
> A simple diffuser may reduce noise but will not
> address these advantages. 
> I've heard that maybe a few hundred rpms are all
> that can really be gained 
> so accuracy will be important.
> 
> I'm not sure if the overlap timing of 4 strokes
> differs much and how 
> sensitive I should be to that.  I have a YS120.
> Would it have the same 
> overlap as a DZ?  If no one can tell me the exhaust
> timing of a DZ, I'll 
> have to get that info on my own before diving into
> the design too much. 
> This will be interesting.
> Thanks again.
> --Lance
> 
> ----- Original Message ----- 
> From: "Bob Richards" <bob at toprudder.com>
> To: <discussion at nsrca.org>
> Sent: Monday, May 23, 2005 8:47 PM
> Subject: Re: 4-stroke carbon pipe design Q's
> 
> 
> > Bill,
> >
> > Ok, if I understand you correctly, the low
> pressure
> > helps suck in the new fuel/air mixture during the
> > valve overlap.
> >
> > Come to think of it, isn't this similar to the way
> a
> > pulse jet works?
> >
> > I guess any kind of backpressure would defeat or
> > minimize the process, which I think is the case
> with
> > our setups.
> >
> > Bob R.
> >
> > --- Bill Glaze <billglaze at triad.rr.com> wrote:
> >> Bob:
> >> One small correction: the outgoing exhaust pulse,
> >> which is under
> >> pressure, creates a small vacuum behind itself as
> it
> >> escapes; this
> >> creates a low pressure area that helps draw the
> new
> >> charge into the
> >> combustion chamber.  I've used a "tuned" exhaust
> on
> >> engines as large as
> >> 540 cu. in. The tuning takes a little time on the
> >> race course, but it's
> >> really worth it.  It doesn't work quite the same
> >> with a blown
> >> (supercharged) engine, because the blower
> pressure
> >> masks the small (by
> >> comparison) vacuum behind the outgoing exhaust.
> >> Bill Glaze
> >>
> >
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> 

Bob Kane
getterflash at yahoo.com


		
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