|
-
POSTING RULES

-
Donate yearly (please).
-
Advertise in here!
-
Today's Posts
|
Insert Pics
|

06-15-2015, 12:32 PM
|
|
|
|
Join Date: Aug 2007
Location: Chico (KCIC) , CA
Posts: 264
|
|
11 to 1??
I do have a wide band sensor I can install temperarily in the bung that the narrow band is in. I will do so... Verify what it reads at peak (hopefully close to (14.7) record peak egts ,record Egts at 11-1 and report back.... At any rate ,if my wide band is, in fact, reading close to 14.7 at peak then I should tune the fuel map to 11 - 1 AFR for take off (full rich) and that should be enough fuel for cooling?
Thx
Gem
|

06-15-2015, 03:32 PM
|
 |
|
|
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
|
|
Quote:
Originally Posted by GEM930
I do have a wide band sensor I can install temperarily in the bung that the narrow band is in. I will do so... Verify what it reads at peak (hopefully close to (14.7) record peak egts ,record Egts at 11-1 and report back.... At any rate ,if my wide band is, in fact, reading close to 14.7 at peak then I should tune the fuel map to 11 - 1 AFR for take off (full rich) and that should be enough fuel for cooling?
Thx
Gem
|
Look forward to your data. Will be interesting.
You should continue to get better cooling right to the point of rich misfire actually.
Also, since flame speed varies considerably with AFR, we should really be advancing timing when running LOP to achieve PCP at the ideal spot for best efficiency. Would be interesting to collect some flight data with regards to TAS vs. AFR vs. total timing on a Lycoming engine.
|

06-15-2015, 05:10 PM
|
 |
|
|
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
|
|
Dan,
Looking at your chart #2.
The data here is a bit questionable IMO since peak EGT is occurring at around 15.3 AFR, somewhat away from what is generally recognized as being stoich, this figure being around 14.5 to 14.8 for gasolines with relatively low aromatics and no alcohol of course. Peak EGT should be occurring very close to 14.7 AFR but it isn't.
This leads me to ask how AFR was calculated- airflow vs. fuel flow in most cases of older dyno data however both devices must be properly calibrated and I've seen enough cases on dynos to know they sometimes are not accurate, especially airflow. Some older Superflow dynos threw out nonsense airflow numbers which did not correlate with the other data.
I'll share my lambda charts with you if you tell us where your info about the widebands came from.
Last edited by rv6ejguy : 06-15-2015 at 05:12 PM.
|

06-15-2015, 06:37 PM
|
|
|
|
Join Date: Aug 2007
Location: Chico (KCIC) , CA
Posts: 264
|
|
I can adjust my timing in flight, but I'm very apprehensive to do so as I'm terrified of destroying my engine from detonation.
Gem
|

06-15-2015, 11:18 PM
|
 |
|
|
Join Date: Oct 2005
Location: 08A
Posts: 9,500
|
|
Quote:
Originally Posted by rv6ejguy
The data here is a bit questionable IMO since peak EGT is occurring at around 15.3 AFR, somewhat away from what is generally recognized as being stoich, this figure being around 14.5 to 14.8 for gasolines with relatively low aromatics and no alcohol of course. Peak EGT should be occurring very close to 14.7 AFR but it isn't.
|
The stoichiometric ratio for 100LL is a bit higher than for typical pump gas...14.9~15.0
Quote:
|
This leads me to ask how AFR was calculated- airflow vs. fuel flow in most cases of older dyno data however both devices must be properly calibrated and I've seen enough cases on dynos to know they sometimes are not accurate, especially airflow.
|
This particular eddy current dyno is installed at the FAA's Hughes Technical Center. AFR was determined using two lambda sensors.
Quote:
|
I'll share my lambda charts with you if you tell us where your info about the widebands came from.
|
Sure, although please note I'm still researching.
First the sensor itself. The manufacturers data sheet is a good place to start.
Bosch LSU4.2
http://www.daytona-sensors.com/download/Bosch_LSU4.pdf
Bosch LSU4.9
https://www.rbracing-rsr.com/downloa...osch_lsu49.pdf
Pretty good discussion of the 4.2 vs 4.9 difference:
http://www.ecotrons.com/technology/b...su_42_sensors/
Par 7.2 in the LSU4.2 datasheet discusses lead:
7.2 Sensors Used with leaded fuel
Depending on the lead contents of the used fuel the expected service life
time is: (preliminary data)
- for 0.6 g Pb/l: 20 000 km
- for 0.4 g Pb/l: 30 000 km
- for 0.15 g Pb/l: 60 000 km
0.6 g/l being about right for 100LL. 20K km is about 12500 miles, or a couple hundred hours in airplane time.
The guy who got 400 hours seems to be pretty famous. Everybody talks about him 
__________________
Dan Horton
RV-8 SS
Barrett IO-390
|

06-16-2015, 10:41 PM
|
 |
|
|
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
|
|
I copied this from your post #67 Dan.
"Right now, leaded fuel apparently makes it necessary to install the wideband sensor very near the exhaust port of a single cylinder, if it is expected to have any lifespan at all. That means the wideband only tells the operator the AF ratio of that individual cylinder."
This was really what I was referring to about where did you get this idea from? Your statement contradicts recommendations coming right from Bosch Engineering who makes these sensors.
We never recommend to our clients that they place a WB in this position since it does not give an average of all cylinders (as you stated), the pressure effects here could skew sensor accuracy (documented by Bosch) and most importantly, temperatures would likely exceed the sensor operating limits here, especially on low compression engines or turbo engines. Ideally, the sensor should be below 1400F so the heater circuit can regulate element temp properly for accurate AFR data output.
Compton's research states a stoich range of 14.5 to 15.0 for 100LL. 14.75 being the mean there. Easy enough for some WB equipped readers to do some testing and report what they find.
BTW, we've been using/ selling LSU4.9 sensors/ controllers for over 3 years now and 4.2s before that dating back to 2006. Lots of feedback from hundreds of customers about sensor life. Worst sensor life story from all those was about 6 hours on a 4.2 running race gas with 6-8 grams TEL/ Gal. 100LL by comparison has 0.5 to 2 grams/ gal. We see the 4.9s certainly lasting longer in a leaded environment than the 4.2s did. Running Decalin lead scavenger with 100LL, we just don't see the short life spans you alluded to. I've sold only 2 replacement 4.9 sensors in the last 3 years out of around 200 WB controllers sold in that time.
I'll check with our high time guy and see where he is at now with his.
I'll email my Lambda/ EGT chart to you tomorrow.
|

06-17-2015, 05:52 AM
|
 |
|
|
Join Date: Oct 2005
Location: 08A
Posts: 9,500
|
|
Quote:
Originally Posted by rv6ejguy
I copied this from your post #67 Dan.
"Right now, leaded fuel apparently makes it necessary to install the wideband sensor very near the exhaust port of a single cylinder, if it is expected to have any lifespan at all. That means the wideband only tells the operator the AF ratio of that individual cylinder."
This was really what I was referring to about where did you get this idea from? Your statement contradicts recommendations coming right from Bosch Engineering who makes these sensors.
|
Agree. I got the "idea" from Robert Paisley, when we were at Barrett Performance last year, in response to my question about lead fouling. My notebook page below. The famous 400+ hours guy came up then too
Quote:
|
We never recommend to our clients that they place a WB in this position since it does not give an average of all cylinders (as you stated)...
|
Not may 4-into-1 and 6-into-1 pipes in the RV fleet. Most are crossovers or individual pipes. You're suggesting 2 or 4 widebands for these installations?
Quote:
|
... the pressure effects here could skew sensor accuracy (documented by Bosch) and most importantly, temperatures would likely exceed the sensor operating limits here, especially on low compression engines or turbo engines. Ideally, the sensor should be below 1400F so the heater circuit can regulate element temp properly for accurate AFR data output.
|
Yep, that's what I read too.
Quote:
|
Compton's research states a stoich range of 14.5 to 15.0 for 100LL. 14.75 being the mean there. Easy enough for some WB equipped readers to do some testing and report what they find.
|
Again, the FAA reported AF values you're disputing were taken using a pair of widebands.
Quote:
|
Running Decalin lead scavenger with 100LL, we just don't see the short life spans you alluded to.
|
Interesting. Wideband users need a fuel additive?
__________________
Dan Horton
RV-8 SS
Barrett IO-390
|

06-17-2015, 09:20 AM
|
|
|
|
Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
|
|
I believe Dan, the value of A/F ratio indication in any engine is beyond question.
Simply pulling the mixture to reduce fuel flow works well but the pilot does not know what is going on unless he focuses on EGT indications carefully, knows what he is looking for; all while flying the airplane and supposedly scanning for traffic.
A/F ratio indication is easy to read. It tells a story and is current. Granted, the O2 sensor installed in one pipe is not optimal but it is better than pulling the mixture with no idea what the resulting fuel air ratio is. 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. But the process was not done in an airplane.
Robert Paisley has a lot hanging on the reliability of the O2 sensor. His entire EFII system depends on it. Their are at least 18 customers using it, someone out there does have 400 hours on the sensor or he would not be saying so. I have been acquainted with him for at least 12 years and he has not disappointed me.
This is not a testimony of Flyefii products. I have no interest in promoting anyone's products. Rather it is a plea to give the 02 sensor with Lycoming a break. If it works, it is very useful information. I do not need the O2 sensor or A/F gauge with EI but it is useful information and will have it.
If the sensor fails early, you will be the first to know about it. 
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
|

06-17-2015, 10:03 AM
|
|
|
|
Join Date: May 2014
Location: Savannah
Posts: 806
|
|
Quote:
Originally Posted by David-aviator
Robert Paisley has a lot hanging on the reliability of the O2 sensor. His entire EFII system depends on it. 
|
The EFII fuel injection system itself does not use an O2 sensor for anything, nor is one even part of the EFII fuel injection kit. The system is open loop and does not rely on O2 sensor feed back for mixture control/air fuel ratio.
__________________
Mike Hammond
A&P IA PPL ASEL
RV-14A kit S/N 140170
|

06-17-2015, 03:36 PM
|
|
|
|
Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
|
|
Quote:
Originally Posted by Mike H
The EFII fuel injection system itself does not use an O2 sensor for anything, nor is one even part of the EFII fuel injection kit. The system is open loop and does not rely on O2 sensor feed back for mixture control/air fuel ratio.
|
I asked about the O2 sensor and Lycoming and this is the response I received.
Hi David,
We put the O2 sensor in the #4 pipe, three inches down from the cylinder. Sensor sitting horizontally, sticking aft off the pipe.
This puts the sensor in the flame front coming out of the cylinder and keeps it purged of lead.
I have more than 400 hours on one sensor using 100LL, no issues.
The Programmer is a 3 1/8" round panel instrument that is included with our full EFII systems.
It gives you full access to the ignition timing curves (and fuel mapping if you have the full system).
It is an option with the ignition systems ($320).
The programmer, which is part of the system, computes and displays A/F ratio , the O2 sensor is part of the programmer, I believe.
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT -6. The time now is 05:15 AM.
|