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Caleb lesher SDS EFI RV-7A

Let's focus...the point is that the sump is only one component in an assembly of components. Every component in the assembly contributes to variance, not just the sump. It's not reasonable to blame one piece alone, or claim perfection for any, including injectors.

Digital injector trim? Yep, no question, the absolute best new development in EAB fuel delivery. Regardless of where the variance comes from, it can be corrected from the cockpit, in moments.

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.

Tell us more about those Vetterman tubes. Got a photo?
 
If I recall correctly, there was an old thread about the bell mouth tubes being installed in the sump, and swedged into place---the guy was looking for the tool to redo the swedge---the internal tubes are effectively a part of the sump, and the tubes running to the heads are separate units.

It is not clear in Dan's image, but the way it looks is like the tube is one continuous piece from bell mouth to the head? Uses a thick wall seal that takes up the extra diameter needed for the bell end to pass through the sump casting?
 
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It is not clear in Dan's image, but the way it looks is like the tube is one continuous piece from bell mouth to the head? Uses a thick wall seal that takes up the extra diameter needed for the bell end to pass through the sump casting?

That's correct Mike.
 
Let's focus...the point is that the sump is only one component in an assembly of components. Every component in the assembly contributes to variance, not just the sump. It's not reasonable to blame one piece alone, or claim perfection for any, including injectors.

Digital injector trim? Yep, no question, the absolute best new development in EAB fuel delivery. Regardless of where the variance comes from, it can be corrected from the cockpit, in moments.



Tell us more about those Vetterman tubes. Got a photo?

In the case of Dave Anders, he had the best stuff he could get on there- flow matched heads from Lycon and a Sky Dynamics intake which follows best automotive practice with a large plenum and tapered, near equal length runners. Even then, we saw variations of a few percent. Compare that to Clark Carrol's roughly 10% max variation. Most combinations are somewhere in between those two sample points. If we strip away each variable one at a time, it seems to me we are left with one conclusion- airflow imbalances exist in these engines to varying degrees due to intake design and port flow differences. We know which variables can contribute to imbalances but without more experimentation, it will be hard to zero in on what is the ultimate combination for a particular engine.

I'm keen to see what Mike's back to back comparisons show.
 
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The 540 and 360 "tuned" sumps differ in that the six banger indeed has the tulips swaged into the sump, whereas the four has one piece tubes from head to tulip.

And yes, Dan, the sump is but one aspect of mixture distribution, but it can be a big one. These "tuned" sumps from Lycoming seem to be taylor made to take advantage of modern EFI and with their big plenum area and tuned runners actually predate the design of automotive EFI intake manifolds by decades.

I believe that Caleb is likely leaving power on the table with the truncated induction tubes he's running. I intend to test that theory with my airplane by experimenting with induction tube length as a means to find optimal VE, but again, I need to get the thing in the air first. That said, Lycoming probably got pretty close with their original design and cutting several inches off the tulips is most certainly going to change tuning. It likely shifts the optimal power range up and out of the normal RPM range we normally fly with.
 
If we strip away each variable one at a time, it seems to me we are left with one conclusion- airflow imbalances exist in these engines to varying degrees due to intake design and port flow differences.

Your are forgetting about the scavenging or restriction that the exhaust system can create in each cylinder. Especially for a NA engine.
 
In the case of Dave Anders, he had the best stuff he could get on there- flow matched heads from Lycon and a Sky Dynamics intake.... Even then, we saw variations of a few percent.

Interesting. You're saying even Lycon and Sky Dynamics can't can't really balance airflow. Probably true, and I'm not surprised. It's a dynamic system.

Re Clark's 10% variance; IIRC he was using an updraft sump, swapped it for an updraft sump from a different manufacturer, and recorded no change. Should we conclude that sumps make no contribution to variance?

Na. I'd still say it's a combination of random contributions from every component, and be pleased that you've developed a way to trim it easily.
 
...Re Clark's 10% variance; IIRC he was using an updraft sump, swapped it for an updraft sump from a different manufacturer, and recorded no change. Should we conclude that sumps make no contribution to variance? ...

I think its reasonable to theorize that the manufacturer of a PMA'd sump will share the gross charactaristics of another, similar design. Most of those updraft sumps share the same choke points. The change to the "tuned" design however represents a significant departure in design. Its as compelling as the difference between the Ford 302 intake of 1970 vs 1990.
 
I think we've covered the many variables which can affect jug to jug airflow variations numerous times before, including exhaust. If you don't have equal length exhaust primaries, chances are that different jugs will "pipe in" and "pipe out" at different rpms leading to improved or degraded scavenging compared to the next jug.

I agree with Toobuilder, sumps with nearly the same design are likely to work similarly no matter what name is stamped on it.

I'd be interested to know how close the primary tube length is on Dave Anders RV4 are since he's got the other bases well covered.

The nice thing about having SDS on an engine is we can easily quantify AFR variations which give quicker results from experimentation.

BTW, auto racing engine designers understood and implemented tuned length intake systems at least 2 decades before Lycoming came up with any of their better designs. https://ixquick-proxy.com/do/spg/sh...105eg.jpg&sp=aa0316b237e5181176cf5b9fcd00472f
 
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Without taking the cowling off, here is the best picture I have of the custom built intake tubes. They terminate right after their O-ring seal into the sump, instead of extending like the Lycoming diagram. I described the combination of sump and Cylinders I had to Clint at Veterman ( super nice guy) who built the exhaust and intake tubes together as a package deal. Probably a less than optimal design with the shorter length tubes, I wonder how much of a difference.


For what its worth, here is a graph of my fuel flow test from yesterday.

The fuel flows are close, but approximate. The leaning process was accomplished by leaning 1% at a time on the SDS mixture knob.


I might lean #4 another % or two. The slight hump in all the lines is probably due to operator error during the test.

Caleb
 
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The SDS system should allow a bit of fairly easy experimentation with intake tube length. Once the engine is all dialed in and even across all cylinders, then any increase in volumetric efficiency will drive a leaner mixture. Suppose you are flying a cruise profile and 100 ROP: IF you could change the length of a single tube, then any improvement in VE would show up as a higher EGT for that cylinder. Continued adjustment of that tube should show a peak in EGT, indicating the highest VE for that condition. That length would be "optimum".

In my case, I intend to fabricate a single induction tube that can be adjusted for length in flight. If my theory holds, I will find my ideal length, and then go back and build 6 new tubes all of that length. In your case however, it seems like it would be easy to simply add a temporary trumpet to one of your tubes and fly it. Start long and cut it down inch by inch, graphing EGT for each change.
 
Congrats Caleb! Very happy to hear your 7 is back in the air. Let me know if you need a copilot. I might need to borrow that crash helmet in about 6 months:D Cheers!
 
Congrats Caleb! Very happy to hear your 7 is back in the air. Let me know if you need a copilot. I might need to borrow that crash helmet in about 6 months:D Cheers!

I'd love to take you along sometime! Still have my number?
 
The SDS system should allow a bit of fairly easy experimentation with intake tube length. Once the engine is all dialed in and even across all cylinders, then any increase in volumetric efficiency will drive a leaner mixture. Suppose you are flying a cruise profile and 100 ROP: IF you could change the length of a single tube, then any improvement in VE would show up as a higher EGT for that cylinder. Continued adjustment of that tube should show a peak in EGT, indicating the highest VE for that condition. That length would be "optimum".

That's a very clever idea Mike.

One detail; as VE improves, the mixture will go leaner as you say (fuel supply, dictated by RPM, MP, and temperature, remains fixed, while cylinder actually ingests gets more air). However, peak EGT does not necessarily indicate best tube length. It merely indicates a tube length where air inducted into the cylinder is a stoich match (aprox) for the fuel supplied. If a further change in tube length continues the trend (improved VE, mixture gets leaner), the EGT will simply start to fall with each change past peak, same as with LOP operation. Best tube length will be found when a length change results in no EGT change (a flat spot, if EGT was graphed). Further length change should reverse the trend (effective mixture gets richer again) as VE gets worse.
 
Good point Dan. I guess the problem is differentiating between the stoichiometric peak, and the max VE peak. Should be a simple matter to achieve a peak EGT (either one) with tube length adjustment, then richen that injector back up to the original 100ROP value and adjust length again. That should be an easy way to determine if it is a VE peak, or purely mixture. It?s a few more iterations that I had originally envisioned, but the injector trim of the SDS product should make it fairly painless.

This is assuming that the ?optimal? length is quite a ways off from what Lycoming came up with. Frankly, if I can move the EGT 100 degrees with tube length/VE alone, then I?ll be amazed. But who knows? It will be an interesting learning experience.

Thanks for the heading check.
 
You could just use the proper tool; an air/fuel ratio meter.

No, wait. you poor Lyc guys are afraid of using mogas, aren't you?

;-)

Charlie
 
Another possibility Charlie. I will have a wideband O2 sensor, at least in the initial setup flights.

And I do intend to run auto fuel if testing proves it out.
 
To his point however, you really only need to test one cylinder. As VE goes up, AFR will lean out... No "false peak" like using EGT.

Not sure what the plenum side of Caleb's induction tubes look like, but in theory it should be easy to add a rubber coupler and a tulip to extend inside. Start out real long and record AFR, Land, remove an inch repeat.
 
Caleb, we took your feedback on the 255-0 wrap-around and incorporated some new code to prevent that on the MAP and RPM fuel parameters. This will be standard in the next software release V29.2. Thanks for that, good idea.
 
Life is interesting in NW California right now. Our main highway to the south is closed due to a rock slide, and not due to open for a while. I took a friend home to Little river (LLR) in about 35 minutes vs the 5 hour detour drive it would have taken. From there I flew to Crescent City CA for a work meeting, and back to Eureka. First time I've gotten to really do some X-C flying with the new engine setup, and a beautiful day!

I ran all ROP this flight. I am skeptical of the accuracy of my Grand Rapids %power display. It is programmed per their numbers for an IO360, but I need to verify them against some lycoming charts.

0420171335 by Caleb Lesher, on Flickr

0420171323_HDR by Caleb Lesher, on Flickr

0420171342 by Caleb Lesher, on Flickr
 
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Took a flight over to Chico, CA this weekend with a friend to eat lunch at Sierra Nevada brewing. We also stopped in Redding CA for a quick visit. The food was fantastic, Northgate aviation at CIC was happy to let us borrow their ford focus. Outside temp was right around 100F at both destinations. I could almost feel heads turning at both airports after the effortless EFI hot start. Cooling seems good. I was able to climb out at WOT, 2500RPM and 120 KIAS while keeping all CHT's under 400 degrees. My cowling does have some extra outlets cut in it from the previous Subaru setup.

Just sneaking up on 40 hours of flight time on this setup, and still very pleased with it.
 
Did some flight testing today. To keep things simple while I've been dialing in fuel settings, I haven't experimented much with timing until today. With a borrowed map from Toobuilder shown below, I noticed an immediate and apparent improvement in mid range smoothness. I'm also amazed how much timing the lycoming likes to idle smoothly. As expected, the engine is much happier lean of peak.
I am also tweaking on my fuel map for a "heat soaked" start up. For about 20 seconds after start, the engine will run slightly leaner until the intake system cools down I'm presuming. I have been experimenting with a larger value under the "start cycles" setting, as well as some added fuel at higher engine temperatures.

Caleb
 
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I'm happy to confirm another happy customer with that map, Caleb. It is a growing list. Please keep us informed of any tweaks to the timing you run across that might be attributed to the EFI. If you do improve on it, then I'll incorporate those changes into the programming for the Rocket's first flight (still months away, I'm afraid).

Have you done any testing to confirm the optimum LOP ignition advance yet? Mine was 3 degrees, but that was with Bendix injection. Interested to see what differences in ignition timing the better atomization of the EFI gives you (if any).

And for all the rest of you, I've been hesitant to publish this map. You should know that it relies heavily on MAP as the primary tuning aid and as such is is pretty conservative at high power, and very aggressive at idle. Anyone who grew up messing with 60's musclecars will recognize the similarity to the logic. Anyway, if there is a fault to this particular method it will be found at flight RPM and low throttle setting such as a letdown/approach to the pattern - be prepared to see 40 degrees advance in the window. Wont hurt anything, but its just a byproduct of the programming method.

Anybody contemplating using this map is welcome to contact me here or via PM.
 
Just a few updates. Tach time is passing 60hrs on the new lycoming without a hiccup. I have updated the pictures I can remember after switching from photobucket to flickr.

A few more pictures of airplane usage!

Took my girlfriend on a vacation to a grass strip camp in, Yosemite, Columbia CA

0422171107 by Caleb Lesher, on Flickr

0422171107a by Caleb Lesher, on Flickr

0422171302_HDR by Caleb Lesher, on Flickr

0422171956_HDR by Caleb Lesher, on Flickr


Visited some friends at the local RC flying field where I learned to fly models at age 10
0504171108a by Caleb Lesher, on Flickr

Of course took dad to shelter cove for lunch
0605171154 by Caleb Lesher, on Flickr

Even the dog approves of the new engine
0613171204_HDR by Caleb Lesher, on Flickr

Screenshot952017-06-13-10-45-54 by Caleb Lesher, on Flickr

Went to 15,500 feet on the way to a week of soaring truckee... just for fun.
0713171148_HDR by Caleb Lesher, on Flickr

0714171414 by Caleb Lesher, on Flickr
 
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On a recent flight, my fuel pressure readout started fluctuating wildly.
my AFR was stable, so I suspected an indication problem. A quick call to GRT confirmed that a common failure mode of the high pressure sensors is to "wear out" a certain range of the sending unit, which then leads to an open signal (max fuel pressure). I ordered their improved 0-100 PSI sending unit and performed the slight modifications to install it. It appears to be a very high quality unit compared to the VDO style sender.

Long story short, after the installation, I couldn't make my fuel pressure adjustments behave how I wanted. I Installed a manual gauge, and calibrated the scale and offset settings in the EIS4000 so the sensor red accurately. I came up with a scale of 75. and an offset of 121. (which was different from the GRT recommended settings)

Things still weren't adding up with my fuel pressure numbers, so I took apart my Aeromotive fuel pressure regular to investigate. As you can see It didn't look very nice inside. It's worth mentioning that this regulator wasn’t supplied by SDS, and the plane had been sitting for a month or more during this time. I cleaned that all up and greased the internal parts. It seems that the steel spring is corroding against the aluminum. Now with a properly calibrated gauge, and a properly working pressure regulator it Looks like I've actually been running on much lower fuel pressure than I thought this whole time. Probably in the mid 20s. With it cranked up to 45 static, the plane runs night and day better LOP. Guessing it wasn't atomizing as well as it should before. It used to stumble and miss past 16:1 AFR, now I can pull it off the lean side of the gauge with the engine still running smoothly, but losing power.

I noted that the top adjusting screw on the fuel pressure regulator isn't sealed against water settling inside the chamber. I've also heard that these diaphragms can be prone to failure.

Might be worth a look and grease come annual time.

happy flying!
Caleb
IMG_20180709_190154 by Caleb Lesher, on Flickr
 
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Good find Caleb.

We see a pretty large number of electronic fuel pressure sensor issues reported. For initial setup, we recommend using a mechanical gauge to verify fuel pressure for setting the regulator.

We didn't supply the regulator Caleb is using. In our regular kits, we supply a US made one by Borla which has a double layer diaphragm made from fluoropolymer. We feel this material and construction is the most reliable available. This regulator has all anodized and SS parts internally.

It's expensive but is a critical part on EFI systems.

 
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Guilty as charged. This regulator was left over from my airplanes Subaru days, and clearly is not the best quality. Another contributing factor is that I like to clean my engine every oil change, and this regulator is NOT sealed against water in its top chamber.

Caleb



Good find Caleb.

We see a pretty large number of electronic fuel pressure sensor issues reported. For initial setup, we recommend using a mechanical gauge to verify fuel pressure for setting the regulator.

We didn't supply the regulator Caleb is using. In our regular kits, we supply a US made one by Borla which has a double layer diaphragm made from fluoropolymer. We feel this material and construction is the most reliable available. This regulator has all anodized and SS parts internally.

It's expensive but is a critical part on EFI systems.

 
Good find Caleb.

We see a pretty large number of electronic fuel pressure sensor issues reported. For initial setup, we recommend using a mechanical gauge to verify fuel pressure for setting the regulator.

We didn't supply the regulator Caleb is using. In our regular kits, we supply a US made one by Borla which has a double layer diaphragm made from fluoropolymer. We feel this material and construction is the most reliable available. This regulator has all anodized and SS parts internally.

It's expensive but is a critical part on EFI systems.


Hey Ross,

1. Which Borla regular is that? (part number)

2. Does it require a MAP vacuum line connected to it or is it regulated via internal spring pressure?...(I think that?s a vacuum line I?m looking at in your picture) If it's vacuum regulated, is that your preference over internal spring regulation?

3. Does it have an internal return/bypass or do you have to run a return line to it from the rail? If someone wanted to run dead-head pressures to the injections from a fuel distribution block or even directly from the fuel pressure regulator then I'm sure the regulator would need to be designated with an internal bypass/return because there would be no return line coming back to the regular from the rail.

Thanks,
Mark
 
I don't have the PN handy at home here but I can PM it to you tomorrow.

We recommend a vacuum line connection in all cases as this maintains a constant differential over MAP. The internal spring establishes the primary fuel pressure.

We usually use a fuel block. The pumps feed the block, injector ports are in between and the reg is connected downstream from this. Returned fuel amount through the reg determines fuel pressure vs. delivery from the pumps and fuel consumed by the engine. At idle, around 99% of the fuel is returned through the reg to the tank.
 
I don't have the PN handy at home here but I can PM it to you tomorrow.

We recommend a vacuum line connection in all cases as this maintains a constant differential over MAP. The internal spring establishes the primary fuel pressure.

We usually use a fuel block. The pumps feed the block, injector ports are in between and the reg is connected downstream from this. Returned fuel amount through the reg determines fuel pressure vs. delivery from the pumps and fuel consumed by the engine. At idle, around 99% of the fuel is returned through the reg to the tank.

Thanks Ross, I'd appreciate a PM on that Borla regular. MagnaFuel makes a fuel pressure regulator that has an internal bypass/return port. So basically the fuel exits the fuel pump, and enters the fuel pressure regulator. The regulator then determines the pressure that's needed to supply the injectors and then ports/returns the unneeded/unused fuel via its return port. It works exactly the same as any other regulator except that it has its own built in port/plumbing for the return fuel, so the fuel that exits the regulator is at the pressure that the user has dialed in and the return line/port is built in to the regulator itself and there's no actual "return" fuel that coming back from the rail or fuel block. It looks like a pretty clean and simple setup and elements a little bit of the plumbing. It's also designed to not use a vacuum line to regulate the pressure. You might want to check it out and see if it'd be a viable alternative to "standard" regulator.

Thanks,
Mark
 


Here is the basic layout we use.



6 cylinder fuel block. Fuel from pumps enters from the right, reg is attached to the left fitting which controls the return fuel volume for pressure regulation.

We don't recommend returnless systems for aircraft because if you suck air by running a tank empty, the engine will stop for a long time while the air is processed by the engine through the injectors. Secondly for hot start, we like to have the fuel purged from the block and feed lines on pump activation.

I'd love to offer a returnless system for ease of installation and we've studied them but came to the conclusion they would be less reliable.

Proper fuel metering without closed loop control is reliant on maintaining a fixed pressure differential across the injector vs. MAP. This is why we use a vacuum reference line on the regulator.

We've been selling these Borla regs for over a decade- zero failures to date as far as I'm aware. We'll stick with that. #1 concern in aircraft has to be reliability and keeping the engine running. As soon as you change hardware, you have no track record to base reliability on. I wouldn't expose our customers to that unknown. We consider historic reliability over a half million flight hours as important and significant benchmarks.

I've seen a number of El Cheapo regs fail completely or deliver inconsistent fuel pressure. Those have no place on aircraft EFI systems IMO.
 
A Brief update: Just completed my oil change at 200 hours on this setup after a flawless 3800NM trip to Oshkosh! Standard procedure for me is to borescope at oil changes. Looks great inside.

Only update with my system has been a change to a GM 1 bar map sensor, and and added small chamber in the line supplying manifold pressure signal to the sensor. The manifold pressure value used to move around slightly, and now its sold as a rock!

Caleb


IMG_20180727_120844 by Caleb Lesher, on Flickr
 
Glad to hear the MAP fluctuations are calmed down to normal with these changes. You're really packing the hours on there Caleb!
 
Small chamber

A Brief update: Just completed my oil change at 200 hours on this setup after a flawless 3800NM trip to Oshkosh! Standard procedure for me is to borescope at oil changes. Looks great inside.

Only update with my system has been a change to a GM 1 bar map sensor, and and added small chamber in the line supplying manifold pressure signal to the sensor. The manifold pressure value used to move around slightly, and now its sold as a rock!

Caleb


IMG_20180727_120844 by Caleb Lesher, on Flickr

I?m just beginning to tune my SDS system and I have some MAP fluctuations also. How does the map sensor you installed differ from the supplied one? I?m also trying to picture the chamber in the supply line. Can you elaborate on that?
 
I?m just beginning to tune my SDS system and I have some MAP fluctuations also. How does the map sensor you installed differ from the supplied one? I?m also trying to picture the chamber in the supply line. Can you elaborate on that?

You might be disappointed to find out that I crafted it in the plumbing department at my local ace hardware as a test. I made mine from 2 3/4" pcv pipe caps, and a union fitting in the middle. Both caps have a 1/8"npt brass hose barb tapped into each side. This is positioned between my map sensor and engine. Out of curiosity, where is your map sensor reference on your engine? I tapped mine right through the back of the sump on my Lycoming.

As far as 1 bar vs 2 bar map sensors, I'm not sure which map sensor Ross is shipping with the units but I'm certain he can chime in here. My system originally started out as a Subaru setup, with the intent of supercharging some day, so it came with a 2bar (0-60")map sensor. These sensors send a 0-5v signal back to the ECU depending on their output. because my plane is naturally aspirated, I was only using half of the sensors scale. I switched to a 1 bar sensor that provides more tuning points, and finer adjustments.

Caleb
 
.... Out of curiosity, where is your map sensor reference on your engine? I tapped mine right through the back of the sump on my Lycoming...

Caleb

Did you tap into the plenum or one of the runners? If the plenum, I'd expect there to be no bounce in the MAP due to the large volume and smoothing effect of the multiple cylinders. I tapped into the TB adapter right below the throttle blades and have not seen any bounce in the few engine runs I've done so far. Many mechanical MP instruments have an adjustable restrictor within the inlet fitting itself. Too wide open and you get needle bounce; too restricted and the needle is sluggish or non responsive.
 
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You might be disappointed to find out that I crafted it in the plumbing department at my local ace hardware as a test. I made mine from 2 3/4" pcv pipe caps, and a union fitting in the middle. Both caps have a 1/8"npt brass hose barb tapped into each side. This is positioned between my map sensor and engine. Out of curiosity, where is your map sensor reference on your engine? I tapped mine right through the back of the sump on my Lycoming.

Thanks for the explanation. My MAP sensor reference is off of the throttle body adapter. I have 90 degree restrictor fitting I made with a .040 orifice on the throttle body adapter. That line then tees to my G3X map sensor then off to my two SDS MAP sensors.

The fluctuations aren?t extreme but it does seems to fluctuate .5 - 1 point. I would like to smooth that out if I could. It?s rock solid on the G3X. I wonder if the 90 degree restrictor fitting is the best choice for this application or if I?m better off with a straight fitting with a different sized orifice? Or just adding in a reservoir like you have done?
 
The 60mm and 80mm TBs we supply now have hose barbs tapped into them now for the MAP sensor. This will save people some trouble on connecting the MAP hose. Having it on one runner is really bad, the sensor just receives a sine wave signal from there.
 
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