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Old 01-16-2018, 04:24 PM
Larry DeCamp's Avatar
Larry DeCamp Larry DeCamp is offline
Join Date: Apr 2010
Location: Clinton, Indiana
Posts: 594
Default Sensor calibration ?

I started this so I will drift the thread a little. All the expert input so far is sincerely appreciated, that was my goal to bring that forth.

One of my big questions when reading about fine tuning ( splitting hairs) in performance is sensor and instrument calibration.From industrial experience, garbage in = garbage out ! I question that certain conditions or performance criteria are claimed when sensor/instrument calibration is completely unknown. I would be reluctant to work hard optimizing a performance objective and know nothing about calibration. Yes relative improvement can be encouraging. If any experts care to comment, we might all benefit 😊
Larry DeCamp
RV-3B flying w/ carb & Pmags
RV-4 fastback w/ Superior EXP 0360 /AFP & CPI
Clinton, IN
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Old 01-17-2018, 08:43 AM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 4,384

I think when it all boils down, what's most important is probably TAS vs. FF since we spend the majority of time in cruise. A four way GPS run combined with one hour set up in cruise conditions on one tank and then refilling that tank on the ground seems like it would have the required accuracy to determine performance to a pretty fine degree.

We have a wideband AFR combined with multiple EGT probes to determine/ crosscheck AFR. We have ignition timing read out in 1 degree increments, MAP in roughly .5 inch increments, RPM at whatever resolution is offered by the EFIS, FF to .1 GPH. Anything more that that is likely outside experimental error margins.

Seems like you have all the tools to make a change and observe the results. You could cross check calibration with known reliable sources if that was a worry.

Dave Anders also uses his Savvy Analysis/ EFIS info and SDS EFI data logging to compare minute data points post flight. Another good tool in the box for those trying to find best efficiency.

Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 420 hrs. on the Hobbs,
RV10 95% built- Sold 2016

Last edited by rv6ejguy : 01-17-2018 at 08:53 AM.
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Old 01-17-2018, 10:17 AM
Dave Anders Dave Anders is offline
Join Date: Feb 2007
Location: cottonwood, calif
Posts: 19

If a person is only wanting to hop in his plane and go at 2000' AGL to a meal and never actually wants their planes best performance then there is no reason to change anything. However if you are one of those that want the best you can do or if your old parts are timing out, then appling the next, more modern, and better technology only makes sense. If you want accurate data, then be certain you are using an electronic panel and downloading it to Savy Analysis and couple that with the SDS data logging you can't generally get better than that for our planes. That will provide hours of ability to accurately compare things.
As for the SDS I'm still extremely happy I decided to go that way. It allows you to sent the parameters as you would like them and then just leave it alone and the engine will perform that way without even looking at. Or, you can require even more from the SDS to fit your mission. I personally like that all cylinders are tuneable in any condition I fly.
Just an additional note that I haven't seen. My ehaust is now always white, which is an indication that it's never running overly rich. The other observation is that my oil doesn't turn black between oil changes from over washing the cylinder walls with excess fuel, and it seems to get better oil mileage. That may be nothing, but it see it.
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Old 01-17-2018, 10:44 AM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
Join Date: Jul 2009
Location: Mojave
Posts: 3,911

Originally Posted by Larry DeCamp View Post
...Yes relative improvement can be encouraging. If any experts care to comment, we might all benefit 😊
Nothing wrong with relative improvement as a final product if you can isolate changes that drive that improvement. The best example of this is adjusting timing on the fly and observing the change in airspeed. Since my only goal is to determine the most power for a given configuration, then peak speed is my only concern. I don't really care if my TAS is off by a few knots one way or the other - just as long as I can identify a peak that directly corresponds to an ignition setting.
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
Harmon Rocket II -SDS EFI instalation in work
RV-8 - Flying
1940 Taylorcraft BL-65 -flying
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Old 01-17-2018, 01:46 PM
N941WR's Avatar
N941WR N941WR is offline
Join Date: Jan 2005
Location: SC
Posts: 11,234

Some time back Mahlon mentioned (I can't recall if it was on this forum or in person) that when they dynoned engines the carburetor versions always put out more HP. (That was a comparison to aviation components, not something like Ross has put together, which is bound to provide max power all throughout the power band.)

The deal is, where do you want your power and how do you fly. When I was doing the car racing thing, I could buy headers for my car that were either four into one or Tri-Y two-in-to-one design. The 4-1 would dyno at max power but the 2-1's would produce more middle band power and have a wider power band. I bought the 2-1's and guys who would drag race would buy the 4-1.

This comes back to what is your mission and desires. Some people want bragging rights on max power and minimum fuel burn. Others just want systems that are bone simple and well known. Bush pilots seem to gravitate towards carbs because they can fix them in the bush. Electronic components can be fixed in the field but usually after a visit from a brown delivery van.

Since an RV is unlikely to land in a place where you life is in jeopardy, if you can't get out (Unless your name is Vlad), we can take some "risk" with our systems.
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
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Old 01-17-2018, 01:50 PM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 4,384

I haven't seen an SDS EFI equipped Lycoming put out less power than a carb or Bendix FI yet, assuming the fuel system is properly hooked up and the timing is set correctly.

Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 420 hrs. on the Hobbs,
RV10 95% built- Sold 2016

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