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  #311  
Old 09-26-2019, 09:11 PM
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vlittle vlittle is offline
 
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Location: Victoria, Canada
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Quote:
Originally Posted by rv6ejguy View Post
The LOP button is designed to be used when you lean the engine to LOP. This advances the timing (usually 3-5 degrees) and picks up some of the power lost when running lean of peak due to the slower burn rate of the mixture.

Usually see 3-6 knots come back over fixed mag timing, depending on airframe and how far LOP you are.

The amount of advance for LOP is user programmable as are the basic RPM and MAP timing curves. In fact, almost every parameter right down to cranking retard and coil charge times can be changed.

This is the "Last Word" in aircraft EI systems where you want full control of your timing and not a canned curve like most other EIs offer.
I'm not from Missouri (actually from Victoria), but all of these claims about ignition timing made me skeptical. I have an IO540 9.2:1 running one magneto and an Electroair electronic ignition.

I have a switch that cuts off the MAP sensor so I can have baseline timing or advanced timing. That also provided me a convenient spot to intercept the advance signal and massage it with an arduino controller.

So I wrote a sketch that allowed me to add or subtract ignition timing in flight and test some of the claims.

The first test was to try changing the timing with a rich 'best power' mixture at 8500 PA. Stock timing from the Electroair was 33 degrees. I tried between 27 and 38 degrees with no measureable change in airspeed of 201 knots.

The second test was to go LOP around 180 knots and find the best timing. Baseline was 177 knots at 33 degrees and 180 knots at 38 degrees. Yeah!

So, based on this rather elementary test, it looks like the 'canned' curve is a bit too conservative LOP, thus proving Ross's assertion. But I also had to watch CHTs in the climb, so maybe it was too agressive ROP. I can always turn off the advance with the switch, though.

So maybe I can change the shape of my advance curve with some simple programming... less advance when ROP and more advance when LOP. I can figure this out from the Dynon serial data stream.

Vern
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  #312  
Old 09-26-2019, 10:02 PM
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rv6ejguy rv6ejguy is offline
 
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Your test results mirror typical experience. We haven't found much difference ROP where power seems to be pretty insensitive to timing (though CHTs usually aren't).

LOP, depending on how much and MAP, typical RVs see 3-5 more knots running 32 to 35 degrees total on PV engines. Really high and LOP, some customers claim around 37ish gives best speed.

If you have a long leg, smooth air and some patience to let things stabilize, you can easily see what timing gives best TAS with the CPI/ CPI-2 under various MAP and mixture settings.

I'd be interested in people's feedback from testing.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 436.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm


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  #313  
Old 09-27-2019, 07:05 AM
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M McGraw M McGraw is offline
 
Join Date: Dec 2012
Location: Greenback, TN
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Default Angle valve engine timing

I have been testing my angle valve engine timing as a function of mixture, RPM, and MAP for about two years. I am very close to what I consider my best curves. I say curves because the most fundamental thing I have learned is that you need a minimum of two curves, one for ROP and another for LOP. My ROP curve covers everything from starting to climb and high power cruise. My LOP curve covers only 2350 to 2700RPM and below 25MAP. Mostly I use it between 18 and 22MAP because of my typical cruise altitudes. I plan to distribute those curves to a friend with a similar engine soon. If he confirms my data we hope to distribute that data to the community.

If you use only one curve you will be too advanced for ROP or not advanced enough for LOP. Both conditions can be acceptable if you set limits on the advance curve, but it is important to understand that too much advance is merely adding heat to the combustion without increased power. A quick summary of my results would be that an angle valve engine and a parallel valve engine respond very differently to advance changes.

All my testing has been done with the SDS EM5 computer which uses the CPI/CPI-2 ignition software, but adds electronic fuel injection.
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  #314  
Old 09-27-2019, 08:43 AM
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rv6ejguy rv6ejguy is offline
 
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We welcome your input on the AV engines Marvin.

BTW, the CPI-2 manual has be updated today on the website. We also now list revisions at the bottom of the manual so you can know what was changed.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 436.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm


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  #315  
Old 10-29-2019, 12:43 PM
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We've got a number of CPI-2s flying now with more coming soon. We encountered 2 installations where there seemed to be incredible amounts of electrical noise in the airplanes and this was often scrambling the data on the programmer LCD and LEDs. The engines always continued to run fine.

If anyone encounters issues with hyrogliphics or blank lines in the LCD or flashing LED indicators, drop me an email or PM and we'll get this addressed at our expense.

Despite extensive testing during development where we sat the controllers right on top of coil packs while they are firing spark plugs a foot away and wrapping the programmer cable around the spark plug wires with no issues, these 2 installations appear to have more noise present than this "worst case" testing scenario. Both of these problem cases have been rectified now with a programmer mod.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 436.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm



Last edited by rv6ejguy : 10-29-2019 at 12:45 PM.
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  #316  
Old 11-04-2019, 06:45 PM
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rv6ejguy rv6ejguy is offline
 
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Location: Calgary, Canada
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Default Magnet Position Values

In case this was missed on our website I thought I'd post it here:

"We've eliminated the need to set Magnet Position with a timing light on Lycoming engines. For engine using the dual pickup, set A ECU Magnet Position to 88 and B to 97. For single pickup installations, set it to 92."

A few new photos of a dual RV-8 install near the bottom of the CPI-2 page uploaded today.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 436.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm


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  #317  
Old 11-28-2019, 04:07 PM
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rv6ejguy rv6ejguy is offline
 
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Location: Calgary, Canada
Posts: 5,423
Default Good Speeds on an RV-8

Kevin Taylor was kind enough to send us a number of photos of his dual CPI-2 install on his RV-8.



This is running LOP. 188 KTAS. Not too shabby on an AV 360.



Kevin also has the new 2 blade Hartzell composite prop which he attributes a number more knots to. He says he's able to hit over 190 KTAS at altitude ROP.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 436.1 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm


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