REFLECTOR: Exhaust upgrade

[Kevin Baker]

Hi Geoff
The rest of us will wait with baited breath at what you find.

Thanks for doing this
Kevin Baker

.

On May 29, 2013, at 9:00 PM, Geoff Gerhardt <geoff.gerhardt at gmail.com> wrote:

> Ruben,
> 
> My exhaust will show up tomorrow.  On Monday, I did some speed runs to gather some "before" data.  Hope to put the new exhaust on on Saturday and take it for a spin.  I'll let you know how it goes.  I have a long flight planned the end of next week.  Worcester, MA to Minneapolis, stay in Minneapolis for several days, then up to Saskatoon SK (Canada).  Hoping the new exhaust works well and gives me a few extra knots for the trip.
> 
> Geoff
> 
> On Wed, May 29, 2013 at 5:07 PM, Ruben Creus <ruben.creus at binnaclecg.com> wrote:
>> Geoff,
>> 
>>  
>> 
>> Any updates on your tests?
>> 
>>  
>> 
>> Ruben
>> 
>>  
>> 
>> From: Geoff Gerhardt [mailto:geoff.gerhardt at gmail.com] 
>> Sent: Friday, May 24, 2013 7:13 PM
>> To: Velocity Aircraft Owners and Builders list
>> Subject: REFLECTOR: Exhaust upgrade
>> 
>>  
>> 
>> 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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