question regarding header & tuned pipe

[Jeff Hughes]

I too run my os1.40 at 1/2 to 1 inch long to smooth out the midrange 
and reduce the peakiness of the engine.


> Bill,
> 
> This may be optimal for top end but where you really want optimal 
performance on a 2 stroke is in the midrange and backing up a little 
helps in that range... so I have been told... and it works on my 
engine...  so THERE.    Heh! heh!....
> 
>  Wayne,
> > 
> > Good suggestion for tuning the pipe, however, there is a school of 
thought
> > that suggests going a little shorter (or past) optimal rpm on the 
test stand
> > when shortening the pipe, because the engine will unload in the 
air thus
> > increasing rpm.  The result is that you're tuning to a higher rpm 
in the air
> > than on the ground, and higher rpm means shorter pipe.  You can't 
really
> > confirm this unless you find a way to tach the engine in the air.  
Just a
> > thought - my $0.02.
> > 
> > Bill
> > 
> > ----------
> > >From: wgalligan <wgalligan at cnbcom.net>
> > >To: discussion at nsrca.org <discussion at nsrca.org>
> > >Subject: Re: question regarding header & tuned pipe
> > >Date: Tue, Mar 25, 2003, 7:40 AM
> > >
> > 
> > > I have a header (Karl Mueller type, one of the best custom mades 
I have
> > > seen) that has a smaller diameter then the pipe itself and it 
does not seem
> > > to effect the tuning.  If you can set up your engine on a test 
stand then
> > > move the pipe to a long setup to begin with.  Then move the pipe 
in a .25
> > > inch at a time and check rpm's.  There should be an increase in 
rpm each
> > > move of the pipe.  Keep moving it till the rpm's max out then 
back the pipe
> > > out to the previous position.  This should be the optimal 
setting for the
> > > top end of the rpm range.  Now this can all change depending on 
prop and
> > > fuel so testing with different combinations is usually needed.  
And the
> > > engine will unload in the air a little too so you might have to 
move the
> > > pipe back a touch.  At least thats the way mine setup the 
best.   Spins a
> > > 17x12N APC @8400 on 15% Cool Power.
> > >
> > > Wayne
> > >
> > >    > Hi, All,
> > >>
> > >> I have a question regarding the header & tuned pipe.
> > >>
> > >> I will be testing a really light Tuned pipe (Japanese F3A pilot 
is testing
> > >> the pipe on OS 140).  It is 550mm length, 48mm diameter, 18mm 
inlet
> > >> diameter.  38g for weight.  I will have to weigh it before 
believing the
> > >> weight of this pipe.
> > >> I believe the pipe is being tested with Hatori/OS header
> > >>
> > >> My headers have diameter of 20mm ~ 22mm (Macs headers) that is 
larger than
> > >> the inlet of the pipe.
> > >>
> > >> Does the differences in the diameter of Outlet of header and 
Inlet of pipe
> > >> make differences when tuning for the pipe?
> > >> thanks,
> > >>
> > >> Ihncheol Park
> > >>
> > >> 1973 White Ave., #402
> > >> Moscow, ID 83843
> > >> (208) 883-7882 (home)
> > >> (208) 661-5018 (cellular)
> > >> PatternFlyer at msn.com
> > >>
> > >>
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> 
> 
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> 

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