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06-17-2015, 04:20 PM
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Join Date: Jan 2008
Location: Upland, CA
Posts: 286
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EFII O2
Actually you are both correct.
We always recommend running an O2 sensor.
It should be installed as quoted in David's post.
This gives long sensor life with avgas.
We have a couple of hundred systems running this way.
The O2 sensor is not part of our kit and does not go through the ECU.
It is for pilot info only.
We recommend running the PLX Devices kit.
These have worked well for our customers.
This is all discussed in our installation manual.
Robert
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06-18-2015, 06:29 AM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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Quote:
Originally Posted by rcpaisley
Actually you are both correct.
We always recommend running an O2 sensor.
It should be installed as quoted in David's post.
This gives long sensor life with avgas.
We have a couple of hundred systems running this way.
The O2 sensor is not part of our kit and does not go through the ECU.
It is for pilot info only.
We recommend running the PLX Devices kit.
These have worked well for our customers.
This is all discussed in our installation manual.
Robert
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Thanks to you and the guy who pointed out my brain malfunction, the knowledge gap is closing.
I will get totally spun up with this system as Ron Burnett is doing it locally. We have been friends and coconspirators since the early EGG days. He is going with the total package, as you know, replacing the Subby with a 0360.
I don't think I will go full plate with EFII but am looking forward to EI and helping Ron get his installed and up and running.
I have the PLX stuff on hand and will be installing it and the EI in late July.
By the way, the fuel pump package is working just fine mounted not flat but on its side. There was not enough room in the 8 where I put it just aft of the firewall.
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06-18-2015, 07:57 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by David-aviator
I believe Dan, the value of A/F ratio indication in any engine is beyond question.
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David, you should not take my comments as a blanket dismissal of widebands. They are a mature technology, and certainly can be useful. The devil is in the details.
An accurate wideband sensor is a practical requirement to set up the fuel schedule with an SDS controller. Using one for setup is much faster than using EGT. It's a great tuning tool.
However, doing that setup on a Lycoming without multiple EGT indications would be a very incomplete picture. As Ross says, A/F and EGT are complimentary. Inability to use and understand EGT is just a lack of knowledge. Sure, it is easy to use A/F, but it is equally easy to go forth using bad A/F information. In any case, the wideband indication from any single cylinder may not be representative of all, in particular when doing new engine setup.
As a long term flight instrument, lead is a factor, and obviously there is some disagreement about wideband installation details among those selling the same FI controller. Have you read the manufacturer's data sheets, and do you understand the accuracy factors Ross mentioned? Are you willing to buy/carry/use a fuel additive ( http://www.aircraftspruce.com/catalo...es/Decalin.php) to extend the life of the sensor?
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The guys running the FAA test dyno had all day, no traffic to scan for and did it very carefully to gather their data which is interesting and useful.
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Actually they do it with a servo, as all they want to do is record a mixture sweep. Trivia.
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Rather it is a plea to give the 02 sensor with Lycoming a break. If it works, it is very useful information.
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No problem. Just remember, it doesn't replace anything, unless you're planning to install four of them. It has the potential to be a good companion instrument, as it may help clarify leaning for some pilots. A/F ratio would indicate LOP or ROP for those challenged by EGT response to knob movement.
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I asked about the O2 sensor and Lycoming and this is the response I received.
...I have more than 400 hours on one sensor using 100LL, no issues....
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Ah, so Mr. Paisley is the 400 hour mystery man? That would have been while flying a Subaru, not that it should make a lot of difference in the context of 100LL and wideband sensors.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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06-20-2015, 09:38 AM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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I've been away for a few days, now catching up on emails and various forum posts.
With regards to the reference 400 hour WB user, no, I was not referring to Robert but another customer who has close to 1700 hours now on the EFI. I'll check with him this week for his WB experiences.
Forum info and general feedback we received on WBs and 100LL (Subarus mostly):
Latest info is that users are generally seeing 50-150 hours WB sensor life using 100LL and Decalin. One reported only 25 hours. Another was at 225 hours so far. People did not know if they had a 4.2 or 4.9 in most cases. On unleaded fuel primarily, 2 reported to have just over 250 hours, one other at 370 another at 445. This field experience is very useful and I hope to have some more feedback next week.
One user reports using a sensor extender to reduce lead accretion on the sensor has so far tripled his sensor life over the original mounting. Probably reduces sensor response time but not so important in steady state operation in a monitoring capacity.
One fellow doing some flight testing on 100LL reported peak EGT coincided with 15.5 AFR, so that supports the Lycoming data Dan provided here. He said his AFRs were changed about 0.5 AFR going from 10% ethanol mogas to 100LL which sounds about right as well.
It's important to understand that WBs were never designed for a leaded fuel environment and almost for sure, sensor life will be impacted substantially when using leaded fuel with them. EGTs are a good cross check which are not affected by lead. Fortunately today, WB sensors are cheap and can be changed out when they go bad.
I agree with Dan here, use AFR and EGT together. Both provide important information and have their place, their advantages and drawbacks.
One more thing to note with WBs, sensors should not be located within 12 inches of atmosphere to prevent false reading due to exhaust reversion. This has "got" a number of people and can present challenges on a fair number of installations. We saw this as a big problem with stack type exhaust systems like on the V6 powered T51s. There is nothing worse than believing you have accurate information displayed when in fact, it's not and you go chasing the solution in the wrong direction. Seen that many times with WBs where a rich misfire will show up as lean since the sensor only sees O2. People end up adding yet more fuel, compounding the problem while scratching their heads.
When I was running 100LL, I used Decalin. No trouble to use and carry in the aircraft, cheap, safe. Something like adding Prist to a turbine aircraft but easier because of the lower volumes added, easy mixing and measuring with the container provided. Decalin is the modern replacement for Alcor TCP.
Last edited by rv6ejguy : 06-20-2015 at 09:45 AM.
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06-20-2015, 10:03 AM
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Join Date: Aug 2007
Location: Chico (KCIC) , CA
Posts: 264
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Egt relationship to AFR
I finally got a chance to fly. Temp was 94* . Take off full rich the AFR was around 10.2 to 1. Climbed out at 120kts. Highest cylinder was 409. My engine only has 35 hours since major and still has break in oil in it. So I can live with that. I climbed to 3500 feet produced power to 19" and leaned to peak.AFR was 14.8-15.1 to 1. Then went full rich. At full rich my AFR was 11.1 to 1. The egt change (ROP) was from 152* on one cylinder to 199*on another, with the other two somewhere in between. Im not sure where I saw the 275* change ROP from the other day??? Maybe my math was off? Anyway there is my info... I'll graph some of my temps and post them if that helps, but the AFR is a separate unit and dose not graph with the temps. 10.2 may be a little rich for take off, but it was running fine and still seemed to be helping with the cooling on climb, so I think I'm going to just leave things alone. I did check the AFR on the lean side and was running about 19 to 1 at 35-40* lop and just starting to feel a little roughness.
Hope this helps.
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06-20-2015, 11:13 AM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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Quote:
Originally Posted by GEM930
I finally got a chance to fly. Temp was 94* . Take off full rich the AFR was around 10.2 to 1. Climbed out at 120kts. Highest cylinder was 409. My engine only has 35 hours since major and still has break in oil in it. So I can live with that. I climbed to 3500 feet produced power to 19" and leaned to peak.AFR was 14.8-15.1 to 1. Then went full rich. At full rich my AFR was 11.1 to 1. The egt change (ROP) was from 152* on one cylinder to 199*on another, with the other two somewhere in between. Im not sure where I saw the 275* change ROP from the other day??? Maybe my math was off? Anyway there is my info... I'll graph some of my temps and post them if that helps, but the AFR is a separate unit and dose not graph with the temps. 10.2 may be a little rich for take off, but it was running fine and still seemed to be helping with the cooling on climb, so I think I'm going to just leave things alone. I did check the AFR on the lean side and was running about 19 to 1 at 35-40* lop and just starting to feel a little roughness.
Hope this helps.
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Great info. Some confirmation that 11 to 1 AFR should be around 150 ROP. Yeah 275 ROP is REALLY rich. 10.2 should help cooling if it's running smooth still. 19 AFR and 40ish LOP does not seem to correlate though. What were your EGTs?
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06-22-2015, 02:43 PM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Old but good...a real Lycoming document plotting EGT against F/A ratio, seven different engines of two engine models, all on the same plot.
Peak EGT is 0.065 F/A, or 15.38:1, which is in agreement with the previously posted run data from the FAA Hughes dyno.
150 ROP is 0.08, or 12.5:1
0.09 or 11:1 is 240 ROP

__________________
Dan Horton
RV-8 SS
Barrett IO-390
Last edited by DanH : 06-22-2015 at 02:50 PM.
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06-22-2015, 04:25 PM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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Quote:
Originally Posted by DanH
Old but good...a real Lycoming document plotting EGT against F/A ratio, seven different engines of two engine models, all on the same plot.
Peak EGT is 0.065 F/A, or 15.38:1, which is in agreement with the previously posted run data from the FAA Hughes dyno.
150 ROP is 0.08, or 12.5:1
0.09 or 11:1 is 240 ROP

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I'll take the real world data at face value (over theory) as some others are coming in with similar numbers after flight testing however absolute numbers ROP or LOP won't be quite the same depending on CR. There could be a 15-25F variation for the same AFR between a 7 to 1 and 10 to 1 engine since peak EGT will change markedly with a 3 point CR change. Minor point.
So on this one, regarding Lycomings, Dan 1, Ross 0. 
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06-22-2015, 05:03 PM
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Join Date: Jun 2006
Posts: 316
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There will be a change in the absolute EGT number for a given CR at the same F/A, but the delta change from peak to a given F/A will be the same regardless of CR. It?s a chemistry thing.
I like your chart Dan.
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06-22-2015, 05:54 PM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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Quote:
Originally Posted by Don at Airflow
There will be a change in the absolute EGT number for a given CR at the same F/A, but the delta change from peak to a given F/A will be the same regardless of CR. It?s a chemistry thing.
I like your chart Dan.
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What is CR?
__________________
RV-12 Build Helper
RV-7A...Sold #70374
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I'm in, dues paid 2019 This place is worth it!
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