1) The engine is a Bruce Turrentine built. Turbo housings and high
>> compression NA rotors. No porting.
>> 
>> 2) The exhaust is a true 2 - 1 header with equal length primaries.
>> I'm a little sketchy on dimensions but my recall is 1 3/4" primaries,
>> 32" long and equal length into a Burns merge collector  2 1/2".
>> Muffler is 4" behind the collector, 2 1/2" inlet and outlet, 28"
>> long, 4 1/2" diameter. It's a spiral flow design, homebuilt, with a
>> relatively large straight tube through the middle. I dont believe it
>> presents any significant restriction. Internals are Inconel and it
>> was in good shape when I had it off the airplane a couple of weeks ago.
 

 

Your exhaust system sounds to be near perfect. I would not suspect problems there.

 

Perhaps TDC mark may be in error. Actual ignition advance between 20 and 25 degrees?

 

Poor inlet shape on TB. Needs trumpet bell. 

 

F/A around 12.7. EGTs 1600 to 1675?

 

Lynn E. Hanover