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  #431  
Old 10-17-2019, 05:42 PM
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jcaplins jcaplins is offline
 
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Quote:
Originally Posted by charosenz View Post
I am continuing to migrate engine systems and components over to the airframe that were functional on the test stand.

Below is a pic of my dual walbro fuel pump system.

I am happy with the set up. For those who may not want to build this piece by piece SDS EFI has a dual pump system that is very compact unit.

I did get my prop today. Very excited to test the engine with this. Unfortunately things are in limbo until I get the fuel system functional and with another trip out of state soon, it may be awhile before I can test the prop.

Ill keep this thread updated as long as there seems to be interest. And since it past over 60k views, I think for now its worth sharing what I am doing.

Charlie
Making progress. Cool.

It looks like there are 2 fuel inputs; one with a filter (the black thing?) and one without. Are you running the return fuel straight back to the fuel pumps? if so, the prevailing wisdom is to run the fuel back to the tank. It's even suggested to run the return line in the tank far from the fuel pickup. This is primarily because the return fuel is warm/hot. I don't know how much of a difference it really makes, my return fuel dumps into the tank right above the pickup tube.

I'm also imagining having the return fuel going back to the fuel pumps would create a problem with regulating the fuel pressure. Fuel would be pumped to and sucked from the regulator, and maybe not suck from the tank.

(Just raising a concern; I don't mind being wrong.)
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RV7 N76CX
(started: Feb 2002 --> Completed: May 2016)
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  #432  
Old 10-17-2019, 10:31 PM
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charosenz charosenz is offline
 
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Location: Longview, Wash
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Default Fuel return lines....

Jeff,

Good to hear from you.

Comments and suggestion are always welcome. I am pretty familiar with the discussion and debate on the returns lines. While I hate to crack open that debate...here are are my thoughts.

I agree that most of the concerns regarding the return line usually is tied to two thoughts. One, like you mentioned is tied to concern about the temperature of the fuel. (which leads to the second concern). High pressure systems like this sees most of the return at idle. While I don't have hundreds of hours of testing on this, I can tell you that the return lines during my testing are not perceptibly warmer than the supply lines, and those, even in the hottest time of summer. The second and actually more common concern is "vapor lock". Many people do not understand that this is a concern for the suction side of the system and virtually a non-issue for the pressurized side of a fuel system. The risks associated with what is commonly called vapor lock are prevalent on a carburetor systems and especially older systems that have mechanical pumps with limited fuel flow, low pressure and long supply lines. The problem occurs when a particular system is unable to move the fuel due to being "stalled" (sometimes called cavitation) with air that that particular system is unable to handle, for a variety of reasons.

When I do my test runs I hook up the system with an external fuel tank. (I don't have wings mounted on the fuse). As you can imagine the lines are nothing but full of air - absolute worse case of risk of "vapor lock". Right?! it takes a few seconds for the air to pass the injectors and then it runs absolutely perfect.

Some even think the return lines are to allow bubbles to return to the tank - not realizing of course that once they pass the pump, the are a non issue. (in a relative sense).

Now, should we be mindful of the value of keeping air out of our supply lines, especially in low pressure carburetor systems. You bet. Will I continue to do testings as the systems evolves? Absolutely.

Sometimes we take information that is applicable to one kind of system and then believe that is applies to all systems even though they are significantly different and that appears to be happening on this topic as well.

In short. Yes, I have thought about it. I have read every tech article I can find and I am basing my decision on credible information, backed by testing.

I appreciate you sharing your thoughts and concerns.

P.S. On a somewhat humors note, I am tempted to put a schrader valve on the suction side and inject very low pressure air in to the system just to verify how it would handle. Any one want to take a $100 bet it handles it fine? I need lunch money.

Take care.

Charlie

Last edited by charosenz : 10-17-2019 at 10:38 PM.
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  #433  
Old 10-18-2019, 07:00 AM
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rv6ejguy rv6ejguy is offline
 
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The biggest concern would be if you run a tank dry, you'll have a lot of air in the system and it will take many seconds to process that through the injectors. The engine will be too lean to run. Maybe not a big deal with lots of altitude but would be down low.

Returning to the pump inlet has caused running issues on the dyno in one instance I can recall during a test.

Any air entrained, going through the pump gears is unfriendly to them.

Returning to the tanks is the safest and most proven. Worth considering IMO.
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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- 435.3 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm


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  #434  
Old 10-18-2019, 10:46 AM
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charosenz charosenz is offline
 
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Location: Longview, Wash
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Quote:
Originally Posted by rv6ejguy View Post
The biggest concern would be if you run a tank dry, you'll have a lot of air in the system and it will take many seconds to process that through the injectors. The engine will be too lean to run. Maybe not a big deal with lots of altitude but would be down low.

Returning to the pump inlet has caused running issues on the dyno in one instance I can recall during a test.

Any air entrained, going through the pump gears is unfriendly to them.

Returning to the tanks is the safest and most proven. Worth considering IMO.
Ross,

Always I good to hear from you.

I should add that my comment about air in the system was certainly not to suggest that it is a good thing, and running a tank dry is definitely not good in any situation, IMHO (Although I have read folks who routinely do that before switching to a full tank - not my idea of good fuel management.)

I mentioned the part about my start ups with air in the line just to help people have a real world perspective and to understand in an unlikely chance an air bubble develops in a system like mine it is (IMHO) not going to cause vapor lock, like in the older low pressure systems.

My testing continues. While the system I had on the test stand was functionally similar, I have not done testing on this particular set up. I hope to get going on it very soon and I will post all my experience, good and bad.

I appreciate comments like yours and Jeff, even while they might be different from my plan they are respectful, and helpful to us all. Your knowledge and experience is something I respect.

Take care.

Charlie.

Last edited by charosenz : 10-18-2019 at 10:49 AM.
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  #435  
Old 10-18-2019, 03:47 PM
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charosenz charosenz is offline
 
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Quote:
Originally Posted by Bavafa View Post
Excited about your progress, can't wait for the time you take it up.

With best wishes
Me too! Thanks for the support. This is a very fun and challenging project. So far I am encouraged with the progress.

Charlie
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  #436  
Old 10-22-2019, 06:57 PM
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charosenz charosenz is offline
 
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Location: Longview, Wash
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Default New prop

Below is a pic of my older 68" Warp Drive Prop that I used for testing, with the new 72" prop.



There are a few things worth mentioning here. Notice the new prop hub. Much "beefier" than the older prop. Warp calls this their HP hub.

Second, notice that the 72" prop blades are full width cord the whole way out to the tip, as compared to the tapered blades on the 68".

Last, you may be wondering why I chose Warp Drives. Really several factors. One, they have been in business for decades with a very good reputation for support and reliability. I have always received great customer service in my dealings with them. That counts a lot to me. I also think the 3 blade 72" full cord set is going to be a good match for my project. They are competitively priced. This prop with stainless steel leading edge, HP hub, crush plate, and bolts and pitch protractor was less than $1700. While it would probably not be a good fit for a IO-360 LYC, I think its going to work out good for me.

I did a real short run up today but I ended up with a coolant issue so I was not able to run it long. I will post a follow up on that issue later.

Charlie
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  #437  
Old 11-01-2019, 10:55 PM
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charosenz charosenz is offline
 
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Default filling and burping the coolant system

In my last post I mentioned the cooling issue again.

I saw excessive high temps on my last short run up. I suspected that it was due to a rather large air bubble near the water pump.

I decided to take more caution on how I fill the coolant in the engine and after doing so I am back with the correct temps and function of the cooling system.

Below you should see a picture of the engine with two reinforced silicone tubes that point straight up in the air. These two tubes are temporarily attached to two ports that just happen to be at the ideal high point of the coolant system on this engine. It is important to note these are on both sides of the water pump and filling them and porting them ensures that the water pump is properly immersed in coolant. The one on the left that has a yellow arrow pointed to it is on the the top of the thermostat housing. The one on the right that has orange arrow pointed to it is on the coolant outlet of the cylinder head where the OEM water temp sensor used to be. (After the filling procedure I attach a a line over to the catch can on the firewall so it can evacuate any remaining air bubbles that may exist as the system is running. That line is marked by a green arrow and is not attached at the time the pic was take.



You can see the bottle of antifreeze that am am pouring in to one of the tubes. As I pour in the coolant, I squeeze the larger sections of silicone in various places in the system to force coolant to move and fluctuate to "burp" the system which encourages bubbles to travel to the high points in the system where those two vertical tubes are temporarily placed.

Unfortunately the last time I filed the system I did not do this process and as a result there must have been a sufficient amount of air trapped near the water pump to cause it to cavitate enough so the coolant would not be properly pumped through the system.

This just highlights the importance of making sure your system is completely filled and no air is trapped in the system. Some engines have bleed ports to release trapped air. I do not believe this system as a port like this.

When I did another run up today the system worked very well. After the engine was properly warmed I ran it up to 4000 rpm.

Much more testing to come.

Charlie

Last edited by charosenz : 11-01-2019 at 11:00 PM.
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  #438  
Old 11-02-2019, 10:41 AM
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rv6ejguy rv6ejguy is offline
 
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Yup this is super important. Trapped air in the system is the #1 cause of overheating issues on liquid cooled conversions that I'v seen and helped people with.

My suggesting to avoid the long filling process is to run a -3 line from one or both of these high points to your coolant tank. This way, any air in the system is automatically bled out when you run the engine. I usually call these active or dynamic bleeds. Saves time and is even better than trying to purge air during the filling process.
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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- 435.3 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm


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  #439  
Old 11-02-2019, 06:28 PM
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charosenz charosenz is offline
 
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Location: Longview, Wash
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Default Active bleed line

Ross,

Yes I do have that dynamic or active bleed line. I may not have explained this well in my post but it is the line in the photo with the green arrow pointing to it. This line goes to the radiator catch can which is the highest point in my system that evacuates any air bubbles that may have been trapped. I only have to do the water bottle fill method if I completely drain the coolant which i did last month when changing the locatiom of one of the two coolant temp sensors.
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  #440  
Old 11-02-2019, 11:58 PM
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charosenz charosenz is offline
 
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Default Pressure testing the Air Intake Plenum

Now that I have the coolant system functioning properly I was able to do a run up to 4004 RPM. Everything seems to be working well. Even after about 4-5 min at 4000 RPM and 33 in Hg I was only at 185 degrees on the hot side of the radiator. I think the cool side was about 165. The water pressure was creeping up quickly though, I think it was at 14lbs. About the point the overflow gets some coolant.

The one think that bothered me though is that was only getting 33 In Hg. I was expecting more with the turbo. After serious contemplation here are some causes that ran through my mind

1) Need to bleed off more air out of the compressor line that goes to the waste gate.
2) Not enough preload on the waste gate arm?
3) Leak or too low BOV setting?
4) Leak in the the intake system somewhere?

For those that may consider a project like this, you need to be the kind of person that is comfortable with dealing with these types of grelims. They will happen. You - at least - have to put up with them, and if you are lucky and you are wired weird like me, you actually like these kind of challenges to conquer.

I decided to hook up a low pressure regulator to the intake plenum. You can see the pic below.



You can see the gauge at the base of the photo connected to my pressure gauge. You can see it feeds in to the intake, the BOV, Intercooler and around the corner that you cannot see is the TB and intake manifold.

I ran it up to 4 lbs. I did not find one leak. I found THREE!

1) One from an abandoned Air Temp sensor. ( I removed this)
2) Some air coming from the current active air temp sensor.(I did my best to seal this using Permatex ultra black)
3) An obscure port on the TB. (I plugged with with foam, Ultra Black and a new cover plate.

It will be set up enough to test tomorrow. First will be to test the BOV to see if it still opens at 12-14 lbs. If that is good I'll do another run up to 4000 may be 4500, may be 5000 rpm

I am hoping to get 40" at 4000 rpm and maybe 45" at 5000 rpm

That would be a mile stone on this project and I would be very happy.

Ill keep you 'all posted. Feel free to ask questions. I even welcome constructive critique, we all need to learn from others. All I ask is the comments are respectful and not denigrating to any person in particular.

Charlie

Last edited by charosenz : 11-03-2019 at 12:00 AM.
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