REFLECTOR: EGT Temps

Scott Derrick scott at tnstaafl.net
Sun Apr 24 17:48:35 CDT 2005


I think  the change in distribution is insignificant.   Another attempt 
to strain gnats.

Once I set my mixture to run LOP at any altitude,  I can vary the 
throttle within a 2300 to 2700 RPM range and the EGT's remain relatively 
constant to each other, which indicates the mixture is stable no matter 
the  RPM .

This is my experience with running an IO470 and a IO360 LOP.

Scott

Chuck Jensen wrote:

>Brian,
>
>You make an interesting point about the relationship between air distribution and RPM.  Accepting your hypothesis that air distribution to each cylinder changes with RPM, then you make a strong argument for CS props.  With a CS prop, I'm only interested in two setting, full power of 2700 and cruise of 2300 or 2400 (if I'm in a hurry).  And, since 2700 is not an issue for air distribution relative to fuel distribution--everything is flat out max, then I have a single RPM that I need to balance air distribution with fuel distribution; 2400 RPMs.  And of course, that's exactly the point/purpose of GAMI injectors and their ilk.
>
>Without a CS, RPM will vary with altitude above 6,500' or thereabouts (and below with throttle setting).  An interesting follow up question is, "if you are running at full throttle above 6,500', does air distribution continue to vary with altitude, as does RPM?"  Even though RPM may vary, the fact you are at full throttle thru all the altitudes above 6,500', perhaps the air distribution doesn't vary with RPM above the critical altitude of 6,500' or where less than full power can be generated.  If the air distribution doesn't change, then the non-CS plane can also achieve an idealized air/fuel mixture delivered to each cylinder, at altitude (where we spend most of our time) by optimizing injector size.  No?
>
>Chuck
>
>Do Not Archive
>
>-----Original Message-----
>From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
>Behalf Of Brian Michalk
>Sent: Sunday, April 24, 2005 3:07 PM
>To: 'Velocity Aircraft Owners and Builders list'
>Subject: RE: REFLECTOR: EGT Temps
>
>
>Agreed.
>
>Another issue is air mass distribution.  The best we can do is make the
>air/fuel ratios correct.  Power levels cylinder to cylinder are different,
>even if they have the right mixture.
>
>Hot cylinder?  Maybe he's just making more horsepower.  About the best we
>could do is to have our induction systems polished, flow tested and set up
>for a specific RPM.  Get off that RPM and the system is out of tune.
>
>The only way out of this would be a throttle-per-cylinder solution.  
>
>If we ever get to this point, it's just splitting hairs.  Not worth the
>complexity/expense/maintenance for a couple percent points of increased
>efficiency.
>
>  
>
>>-----Original Message-----
>>From: reflector-bounces at tvbf.org 
>>[mailto:reflector-bounces at tvbf.org] On Behalf Of Chuck Jensen
>>Sent: Sunday, April 24, 2005 6:31 AM
>>To: Velocity Aircraft Owners and Builders list
>>Subject: RE: REFLECTOR: EGT Temps
>>
>>Becks,
>> 
>>The difference in EGTs may be....nothing.  The EGT values are 
>>easily influenced by the placement of the probe, among many 
>>factors.  First, check during cruise by turn off one 
>>    
>>
>
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