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  #41  
Old 03-13-2017, 12:44 AM
Captain Avgas Captain Avgas is offline
 
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Originally Posted by rv6ejguy View Post
Great job and nice pix. The smile says it all...
That's the smile of someone who has ditched a dodgy auto conversion and installed a Lycoming. There's nothing like stress-free flying to bring on a big grin
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  #42  
Old 03-13-2017, 06:01 AM
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Originally Posted by Captain Avgas View Post
That's the smile of someone who has ditched a dodgy auto conversion and installed a Lycoming. There's nothing like stress-free flying to bring on a big grin
I think Caleb enjoyed flying the Sube but he can comment on that.
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 441.0 hrs. on the Hobbs,
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  #43  
Old 03-13-2017, 08:01 AM
Tomcat RV4 Tomcat RV4 is offline
 
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Congratulations! I am jealous,as I have my Rv4 w 2.5 suby waiting for me to get back to NY from Fla. AW, Taxi testing fuel & cooling no leaks,ready for good preflight and then fly.Tom
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  #44  
Old 03-29-2017, 10:16 PM
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Norcalrv7 Norcalrv7 is offline
 
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Had some smooth weather today, So I took advantage of it do so some Individual cylinder trim testing. This is a freshly overhauled parallel valve engine with Lycoming Horizonal sump, and some custom intake tubes from Vetterman. Some initial numbers look like cylinder trims as follows:

1= -2%
2= +3%
3= -2%
4= +2%

These settings resulted in a GAMI spread of .2GPH for my setup.
Not surprised to see the wide variance due to the poor intake sump design.

I plan on doing more testing to verify this data is repeatable.

I made a nice spreadsheet on my laptop to graph my EGT data in realtime, and make adjustments in SDS without having to land and pull datalogging information from the EIS. And yes, that is a green cushon from the hangar couch in my copilot seat that serves as a laptop mount :-)

0328170827_HDR by Caleb Lesher, on Flickr

Caleb
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Last edited by Norcalrv7 : 08-28-2017 at 09:43 AM.
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  #45  
Old 03-30-2017, 10:30 AM
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Toobuilder Toobuilder is offline
 
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I initially missed the fact that you have adapted the "tuned" 200 HP sump to your parallel valve engine. I think thats a great idea as I'm doing the same with my Rocket, but I am going to fly with the original 260 HP sump for a while then do the switch. On paper, the factory tuned sump is vastly superior to the standard version due to increased plennum volume, runner approach angles and runner length. The proof, of course, can best be verified with testing.

You are seeing a bit of a "GAMI spread" with this new intake, but I suspect you would see a bunch more variation with the stock sump. As stated above, I intend to fly and tune the stock sump, then do the switch and document any change. I have set up the stock sump with a raised throttle body adapter so that it will be the same height as the tuned sump - meaning that I will not have to change any other performance variable except the sump itself.





It is a shame (but understandable) that you did not have any before and after info with this sump, but hopefully I will be able to fill in that blank in a few months.
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Last edited by Toobuilder : 03-30-2017 at 10:46 AM.
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  #46  
Old 03-30-2017, 01:39 PM
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Norcalrv7 Norcalrv7 is offline
 
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Wow looks very nice! I keep forgetting that my sump/tubes/cylinders are a hybrid design. The Horizontal sump certainly has more volume than the stock -B1E Rear induction sump I started with. I'm not sure the model number, but mine is NOT the style where the tubes cross each other inside the sump with bell style intakes. My performance numbers seem to be somewhere between the 180 and 200 HP numbers, and my airplane is 100lbs heavier than It should be. Would be interesting to see how much of a gain the sump, ram air, and EFI all add up to individually.

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  #47  
Old 03-30-2017, 03:34 PM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by Norcalrv7 View Post
Wow looks very nice! I keep forgetting that my sump/tubes/cylinders are a hybrid design. The Horizontal sump certainly has more volume than the stock -B1E Rear induction sump I started with. I'm not sure the model number, but mine is NOT the style where the tubes cross each other inside the sump with bell style intakes. My performance numbers seem to be somewhere between the 180 and 200 HP numbers, and my airplane is 100lbs heavier than It should be. Would be interesting to see how much of a gain the sump, ram air, and EFI all add up to individually.

Caleb
So the standard B1E sump looks much like my D4A5 sump- very little plenum volume, tortured runners and all bathed in hot oil.



But yours appears to be the cold air sump, much like this:



If you do not have the individual tubes extending into the plenum, what do you have?
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RV-8 - SDS CPI
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1984 L39C
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  #48  
Old 03-30-2017, 03:47 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by Norcalrv7 View Post
Some initial numbers look like cylinder trims as follows:

1= -2%
2= +3%
3= -2%
4= +2%

These settings resulted in a GAMI spread of .2GPH for my setup.
Not surprised to see the wide variance due to the poor intake sump design.
Plus or minus 2% is the standard flow tolerance for off-the-shelf electromagnetic injectors. The restrictors we use in constant flow systems are probably similar. Either can be flow-matched into sets on a bench.

Clearly variation exists in mass airflow too, and note there's more to that than just the sump. However, reality is random variation in both fuel and air delivery.

Install a set of flow matched injectors, then look at the peak spread.
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  #49  
Old 03-30-2017, 10:29 PM
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Norcalrv7 Norcalrv7 is offline
 
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I purchased the Lycoming "bat wing" style sump during my engine overhaul. looking back at the pictures it is stamped "74664". It appears in this style sump, the intake tubes normally extend into the sump to form the bell mouth tubes. My intake tubes (made by Vetterman) end after the 0-ring seal.

I red one thread a while back about someone experimenting with intake tube length optimization, but never heard anything specific, anybody have input here? I am more than happy with my mixture distribution. As DanH said, even 2-3% is acceptable variance with electronic injectors.

Sump visible in lower left

2016-03-14 11.37.09 by Caleb Lesher, on Flickr
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Flying RV-7A N542LC with SDS Electronic fuel injection.
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Air Ambulance driver
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Last edited by Norcalrv7 : 08-28-2017 at 09:43 AM.
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  #50  
Old 03-31-2017, 06:29 AM
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rv6ejguy rv6ejguy is offline
 
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Before we had the mixture trim option available, users would swap a "cold" injector to the "hot" hole to see if the injector was causing the issue. I did the same in my Subaru engine. Never saw any significant change, indicating the injectors we use are typically flow matched to something less than 1%.

When I used to flow test injectors a lot of years back, I rarely saw more than 1% variation on Bosch injectors. Less than that was hard to read on the graduated cylinders and was the within experimental error of the test rig.

1% is truly splitting hairs and makes no significant difference to engine performance.

Others in the past here have disputed the large GAMI spread present on some sumps is due to airflow imbalance and when I called them out on the tailored Bendix type injector size used to fix the imbalance (calculated area), they suddenly became silent.

There have been a couple large threads on these matters here on VAF. I'll repeat what I said then:

1. Equal airflow to each cylinder is ideally what we want. This results in near equal hp being produced by each cylinder, the smoothest possible running and all cylinders to peak at nearly the same time so we can lean all to nearly the same AFR.

2. Tailoring mechanical injector sizes or electronically altering the pulse width on EFI injectors to match the airflow imbalance present is a partial patch for the true issue. It's clearly better than not doing anything.


The EFI trim option is a huge time saver- it simply doesn't care whether the AFR imbalance is caused by airflow or injector fuel flow variations- you don't need to get out of the cockpit to correct your AFR in each cylinder and you can do it at any power setting, not a fixed, relatively narrow range as with mechanical FI. Customers are embracing that technological leap along with the other demonstrated advantages of EFI like no hot start or poor idle issues.

We've seen the flight testing by Dave Anders (with flow matched cylinders) and others using our EFI to trim each cylinder in flight at any rpm/MAP combination to within 1% as being able to extract the best from their installed intake system. In Dave's case, at extremely low power settings, he was able to still balance the cylinders down to impressively low fuel flows with very decent TAS numbers. Not everybody flies like this but it shows the superior fuel metering capability of EFI over legacy mechanical FI systems which don't work well in this regime. This is really as good as it gets until someone produces the perfect Lycoming sump with equal airflow at all rpm/MAP combinations.

I applaud the experimentation of Caleb and Michael here. We'll learn some more about this fascinating subject.
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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- 441.0 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm



Last edited by rv6ejguy : 03-31-2017 at 07:37 AM.
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