question regarding header & tuned pipe

[Bill Carpenter]

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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