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Old 07-25-2017, 10:17 PM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
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Location: Calgary, Canada
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Default SDS EFI Individual Fuel Trim

Here's a graphic example of this option in actual operation on an IO-550TT:



This customer prefers to balance his CHTs with the trim function.

We can get the same level of control and precision on Lycoming fours and sixes as the basic systems are almost identical.
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Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW- 416.6 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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  #2  
Old 07-26-2017, 06:20 AM
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KRviator KRviator is offline
 
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Someone's going to ask it, might as well be me...Why balance your CHT's instead of the EGT's given the CHT's can be influenced by things like baffling and are somewhat unrelated to the actual smoothness of the engine when leaning?
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Old 07-26-2017, 06:43 AM
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Quote:
Originally Posted by KRviator View Post
Someone's going to ask it, might as well be me...Why balance your CHT's instead of the EGT's given the CHT's can be influenced by things like baffling and are somewhat unrelated to the actual smoothness of the engine when leaning?
The actual EGTs don't mean too much, where each cylinder peaks is the important criteria as this indicates the AFRs are the same.

In this case, Andrew has the baffling well sorted and the engine is ultra smooth. I'll ask him and see what the GAMI spread was in cruise with this trim setup. Perhaps it all falls together.

It's unconventional as you say but seems to work. He took first place in Experimental Sport at the AVC race on the weekend.

Edit: As I was driving to work, I was thinking about this more. Andrew is a pretty smart guy. If we look at why we get different cylinders peaking at different times when we know we have near equal fuel flow, it's because the airflow to each port is not the same as I've discussed in previous threads. If we assume perfect baffling and cooling mass flow to each cylinder for discussion, perhaps Andrew's method makes more sense than what conventional EGT based trimming is doing for us. Assuming the prior statement, Andrew is tuning for equal heat/ HP in each jug which should equal smoother operation than the EGT method which equalizes AFRs but not power between cylinders, since internal airflow is not equal. Food for thought.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW- 416.6 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm



Last edited by rv6ejguy : 07-26-2017 at 07:30 AM.
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