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10-08-2014, 05:41 PM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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Quote:
Originally Posted by grubbat
Hi Mike,
I was using the other variables just as an example. The point I was trying to make is that we think we know what the variables are and sometimes we do. However, a OFAT experiment greatly limits your knowledge gained because we just do not have the time and money to investigate all the corners of the frame in question. In the past, designers / innovators just had to choose through experience or past knowledge what they thought might be the significant drivers. Sometimes they were right. Sometimes, after a lot of experiments, time, and money, they learned something. Changing one factor at a time now a-days is just simply too costly. OFAT is still taught in some schools because it is easily understood. However, the top tier schools, NASCAR folks, and top quality institutions are utilizing/teaching Design of Experiments (DOE).
I was teaching this stuff back in 2000. I had a couple of great Quality mentors from Allied Signal that showed me the light back then. At the time, we were only a handful of folks (in the world) who knew about AND actually practiced DOE's. It's really can be a useful tool.
In real life, interaction within and between variables is real and very common and sometimes nonlinear. Try figuring out a non-lineral interaction with an OFAT experimentation. Gives me heart burn just thinking about it.
As far as how do you know which factor or variable is significant, which one isn't, which one is interacting with another one, and what variable that you thought was significant when in reality isn't so much, well, that's why the DOE was born. Software such as Minitab makes it easier than slide rule.
cj
P.s. Ross, you are correct that most people do not use it. However, the smart ones do. Of course, when you are talking about running a multi-million dollar engine in a test cell, time is money. (GE did it, Allied did, and others also. To compete, you have to.)
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Engine development projects are time consuming by nature and dyno testing can become a tedious but rewarding learning experience as part of that. In this case, the point was to quantify the result of a SINGLE change. Your theory simply has no merit as a time saver in this instance.
We already well know what the external variables are for about the last 100 years. They are controlled for the most part. What we don't know is the effect of the mechanical changes we make to the system.
We have computer tools to predict lots of things these days- dyno in a PC, CFD to design aircraft and gas turbine engines etc. These are big time savers but in the end, we still validate the design through actual testing. In the case of big projects like new aircraft or gas turbines, this still involves thousands of hours. Simulation simply isn't a substitute for real world testing and it's not accepted by the powers that be like the FAA. We still see failures in the most heavily engineered devices like the PW F135 and PW1500G engines recently.
For something like the tests we are talking about in this thread, it is way way cheaper to simply put the engine on the dyno, baseline, make the single change to the EFII system and observe/ report the results. Your posts, while food for thought perhaps in other fields and endeavors, don't make much sense in this case where a few hours would have given a solid answer.
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10-08-2014, 06:41 PM
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Join Date: Aug 2010
Location: San Luis Obispo
Posts: 199
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Quote:
Originally Posted by tadsargent
Did I miss the horse power number in this thread?
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I think it was lost forever  ...
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10-08-2014, 07:22 PM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by tadsargent
Did I miss the horse power number in this thread?
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Tad, it was 276 vs 265. All this argy-bargy and dog-ate-my-homework over a whopping 4%.
Never mind that I also reported 194hp @16.3 GPH on mags and Bendix, vs 190hp @14.8 GPH with the EFii systems, both at 24/2400. That's 2% hp for 10% less fuel, at a high cruise power. If you could claim that, would you make a fuss and draw attention to the other?
Quote:
Originally Posted by rv6ejguy
For something like the tests we are talking about in this thread, it is way way cheaper to simply put the engine on the dyno, baseline, make the single change to the EFII system and observe/ report the results.
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Sounds familiar.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Last edited by DanH : 10-08-2014 at 09:25 PM.
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10-09-2014, 03:26 AM
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Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,271
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Dan, those HP and fuel flows, they would have to be ROP. BSFC around 0.498 for the Bendix and 0.46 for the EFII.
As it was being run ROP there could be any variation applied on the rich side. So you can make a ROP HP rating vary by tiny amounts but with considerable fuel flow differences. Not that I need to tell you that of course. But many reading this may not pick up on that.
So what data did you gather at best BSFC at 24/2400 for arguments sake? (or any other setting). I would expect that the EI would achieve a good number. I get something like 0.397 with my stock so it would make for interesting viewing.
I hope you had time to collect it. Would have been a fun day testing.
Be nice to see the ambient and the CHTs for both cases. Not that it is a direct substitute for peak ICP and ThetaPP but it would give a guide as to what stress is being applied in achieving the results.
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David Brown
DYNON Authorised Dealer and Installer
The two best investments you can make, by any financial test, an EMS and APS!
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10-09-2014, 06:00 AM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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Quote:
Originally Posted by Bluelabel
The results:
The big one that we were all watching was of course the WOT HP reading. ........All of the above leads me to believe that our test results got scewed, We?ll never know for sure, unless we do it again. (Which we will?..stay tuned)
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Thanks for the report, John.
I am no expert on the design of EFII but have faith in Robert Paisley and Allen Barrett. They are credible and knowledgeable.
My experience with EFII and the Subby engine was good except for the sub system failures of the engine and inadequate cooling. If I were younger and richer I would be perusing with the 0360 what you are doing with the IO-540. It is exciting, smooth and fun to experience the effect of EFII and an engine.
Again, thanks for reporting your adventure in this area.
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RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
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10-09-2014, 06:42 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by RV10inOz
Dan, those HP and fuel flows, they would have to be ROP. BSFC around 0.498 for the Bendix and 0.46 for the EFII.
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The previously posted values had a calculated BSFC of 0.483, with the appropriate correction for fuel density. It's on the chart in the article.
Quote:
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So you can make a ROP HP rating vary by tiny amounts but with considerable fuel flow differences. Not that I need to tell you that of course. But many reading this may not pick up on that.
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Right. They shouldn't have any trouble picking up on it, as the article states "The fourth and fifth tests were more subjective. We would have Barrett set 24 inches/2400 and 19.5 inches/2400 to simulate cruise conditions, then search for the lowest possible fuel flow without significant torque loss?"
The article is available to all subscribers as a PDF download, so I'm sure anyone who wishes to read for themselves can obtain a copy sooner or later.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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10-10-2014, 01:27 AM
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Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,271
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Thanks Dan,
I will keep my eye out for a copy down here. Unless you can email me the article you wrote. It would make a good read.
__________________
______________________________
David Brown
DYNON Authorised Dealer and Installer
The two best investments you can make, by any financial test, an EMS and APS!
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10-10-2014, 02:02 AM
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Join Date: Aug 2005
Location: Pasadena CA
Posts: 2,484
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Quote:
Originally Posted by DanH
Tad, it was 276 vs 265. All this argy-bargy and dog-ate-my-homework over a whopping 4%.
Never mind that I also reported 194hp @16.3 GPH on mags and Bendix, vs 190hp @14.8 GPH with the EFii systems, both at 24/2400. That's 2% hp for 10% less fuel, at a high cruise power. If you could claim that, would you make a fuss and draw attention to the other?
Sounds familiar.
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Perhaps the frustration stems from different, more favorable (for the EFI managed engines) results that came out of a similar test, on a correctly set up dyno, 2 days later. Results that you were aware of before the story went to print, but chose to run anyway?
I mean, I don't have any affiliation with Protek, other than knowing Robert from CCB. I simply looked at their system, compared to all the other EI systems I've worked on or installed, and determined that the EFII system is the only one worthy of a dual EI installation from a hardware standpoint.
For an up and coming company, to have their first major dyno shootout go like that, and for a major industry magazine to publish 'results' without a follow up on a dyno that is properly set up might be frustrating. Especially since HP sells systems, not MPGs.
__________________
Stephen Samuelian, CFII, A&P IA, CTO
RV4 wing in Jig @ KPOC
RV7 emp built
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10-10-2014, 06:24 PM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by osxuser
Perhaps the frustration stems from different, more favorable (for the EFI managed engines) results that came out of a similar test, on a correctly set up dyno, 2 days later. Results that you were aware of before the story went to print, but chose to run anyway?
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As usual, things may not be quite what they seem.
Sunday afternoon, June 29th, Robert and I were on the phone almost an hour:
Among other requests, Robert asked that I call Kevin Eldredge and consider their results. I agreed.
I called Kevin on Monday. We discussed a number of points. The actual conversation is off the record. However, it breaks no confidence to tell you I asked Kevin for a complete dyno printout comparable to the Barrett dyno logs.
I sent a follow-up email the same afternoon:
From: Dan Horton
Sent: Monday, June 30, 2014 12:42 PM
To: kevine@titan.com
Subject: Dyno Data - EFII
Kevin,
Thanks for taking my call. Again, I apologize for the intrusion, but Robert insisted that I contact you, and I promised.
As discussed, any data you may choose to supply is off the record until agreed otherwise. Published or not, it would be interested to examine the raw dyno record for the same engine, run with conventional and then EFII systems.
In any case, please log my email and cell phone, as we’ll no doubt have fun things to talk about in the future.
On Wednesday, July 2nd, at 8:34 PM I responded to a note from Robert:
As promised, I spoke with Kevin about midday on Monday, and requested a raw dyno download for the same engine, run with conventional systems and then EFii systems. He agreed to send along some data, which will be off the record until agreed otherwise. As of tonight, I’ve not yet received it.
On Thursday, July 3rd, I followed up with Kevin by cell phone:
And this by email on Tuesday, July 8, at 1:44 PM:
Hi Robert,
Kevin and I agreed Titan dyno data is off-the-record. Although I am very interested, as it stands now I can’t publish it, or even refer to it, without a new agreement with Kevin.
The current information is very limited. For example, there is no indication if these are brake or corrected HP values, no IAT, baro, or humidity, and no comparison CHT’s, EGTs, BSFC, and fuel flows. No dates either. Is the AFP/Lightspeed data from some previous time? How much has the engine run since then? If it was flown (like for the prop vibration survey), I would expect it to make more power as it loosened up.
Think you can get a complete information, and Kevin’s blessing? Editorial deadline is the 10th.
In the end, the deadline was extended a month. I never received the Titan dyno log. Robert did send a single Excel graph showing a HP gain of less than 1% at 2700 RPM, hardly a game changer. As noted, I couldn't use it without Kevin's permission, which I did not receive, and anyway, could not have printed it without supporting information similar to the Barrett data.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Last edited by DanH : 10-10-2014 at 09:18 PM.
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10-14-2014, 07:57 AM
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Join Date: Aug 2005
Location: Pasadena CA
Posts: 2,484
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Quote:
Originally Posted by DanH
In the end, the deadline was extended a month. I never received the Titan dyno log. Robert did send a single Excel graph showing a HP gain of less than 1% at 2700 RPM, hardly a game changer. As noted, I couldn't use it without Kevin's permission, which I did not receive, and anyway, could not have printed it without supporting information similar to the Barrett data.
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So what you are saying is, a 4% loss in peak HP from stock mags and injection compared to a 1% gain over a LIGHTSPEED equipped engine wasn't enough for you to wait for another test that everyone else involved thought was necessary? It just seems irresponsible to print data you know isn't complete, especially since the reasons for the low numbers during your tests were obvious and known going in, lacking a dyno with a fuel return line.
__________________
Stephen Samuelian, CFII, A&P IA, CTO
RV4 wing in Jig @ KPOC
RV7 emp built
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