REFLECTOR: Exhaust upgrade

[Geoff Gerhardt]

Guys,

I've ordered a new set of pipes from Clinton at Custom Aircraft Parts.  I
will be replacing my stock Velocity exhaust that are 2-1 and vent out the
bottom of the cowling.  The exhaust from Custom Aircraft is a set of 4-4
pipes that will vent out the rear of the cowling into the prop.

I will collect some good data this weekend (weather permitting) of my
current performance.  Hopefully by next weekend, I'll have the new exhaust
mounted and can collect data with it installed.

Here's what I'm expecting:

   - Clinton has indicated that going from the 2-1 stock Velocity exhaust
   to the 4-4 will result in a significant HP boost (12-18HP).  He thinks that
   the 2-1 format for an IO-360 is the worst configuration, as the exhaust
   pulse from one is interfering with the intake for the other cylinder.  He
   expects that I will see a measurable and significant increase in static RPM
   with this switch.

   - I expect my CHT's will drop.  I have pretty big holes for my existing
   exhaust to exit the cowl.  I think this is adding a lot of pressure to the
   lower cowling.  Also, venting the exhaust out the rear of the cowling will
   actually create a vacuum inside the cowling.

   - Cruise TAS?  Who knows.  We'll see if there is, indeed, some drag from
   the exhaust disrupting the airflow.  The added HP will help, I suppose.


If anyone has some suggestions for a test flight that will provide good
comparative data, please let me know.

This exhaust system will cost me $1200.  He indicated that he would lower
the price if more orders were rec'd.  He wouldn't give me a lower price by
acting as the guinea pig and providing good before/after test data, but
said if anyone mentioned my name, he would give me a percentage of the
sale.  So, if after you see the data from my testing and you want to order
a similar set of pipes from Clinton, mention my name.

Geoff
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