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Date: Tue, 29 May 2012 19:37:42 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Exhaust temp
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On 05/29/2012 01:12 PM, Ernest Christley wrote:
> Lehanover@aol.com wrote:
>> I was hoping you wouldn't see this, but now that the cat is out of the
>> bag............
>>
>> You can see the need for some shielding between the headers and any
>> items that you don't want at the same temperature. Radiant energy is
>> line of sight. If the header can see it, up goes the temperature.
>>
>> Pieces of .015" stainless stood off the header about 1/2" to 3/4" breaks
>> the line of sight. Building such on the header reduces the amount of
>> material involved. It is easier to not heat things up than it is to cool
>> it after you have. Use 1/4" hose clamps to hold onto the shielding.
>>
>> A small blast tube to keep things moving past the headers is helpful.
>> I can make a picture if you like. Helps keep heat out of the intake
>> system and thus more power. Very easy. Amazing results.
>>
>> Lynn E. Hanover
>>
>>
> My exhaust is encased in a .015 stainless box down to the end of the collector.  The down pipe and muffler are exposed,
> and I see where it is blistering the belly paint already.  I'll be wrapping more of the exhaust in the thin stainless.
> I will also open the stainless box up to allow some blast air through. First I have to change that down pipe from 1.5"
> dia to 3".  I can't seem to get above 5100RPM, and I think exhaust backpressure is my issue.
>
As someone else pointed out, it would pay to look at the prop first. 
What's the prop rpm? If it's anything close to typical a/c engine static 
rpm (2000-2300, depending on pitch), then you might be able to borrow a 
regular wood prop from someone to use as a benchmark. Knowing the design 
HP & static for a specific prop, & checking your performance against it, 
will give you a much better handle on how much power you're actually making.

Charlie