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Honda 1.8L on RV6A Now Flying!

honda vs rotex

Your engine is rated at 110 hp and has no time restriction ( 5 min on rotax ) the Rotax must drop to 80 hp after 5 min,s a big plus on climbout
 
Charlie,

I know nothing about your engine, but some water cooled engines can be really tough to 'burp'. If you're boiling coolant, any chance you haven't cleared all the air from the engine itself? If the combustion chamber areas are getting minimal water flow, it will boil more readily.

If you're seeing a large temp drop across the rad, perhaps there's minimal water making it through the rad. That would allow the rad to drop the temp a lot more, especially if there's a significant pressure drop across the rad and the water is flashing to vapor in the rad.

On the subject of bypasses: again, don't know your engine. But the Mazda rotary I'm installing has as its stock thermostat a version opens a bypass when cold and plugs the bypass forcing flow through the rad as it heats up. Everyone I know about using the rotary plugs this bypass, and uses either a standard thermostat, or no thermostat at all for a/c use. *If* your engine uses this type of thermostat, and it's stuck in 'cold mode', minimal water might be flowing through the rad (see above).

Again, raw speculation. But guys flying rotaries have seen the issues I described.

Charlie
 
Everyone I know about using the rotary plugs this bypass, and uses either a standard thermostat, or no thermostat at all for a/c use.

The reason for a bypass closing thermostat is to maintain a constant flow velocity through the heads and around the cylinders regardless of the thermostat position. It can be critical for high load factor engines - aircraft engines operate at a high load factor. So, if it is really cold and the thermostat is nearly closed, then you would not want the coolant velocities reduced and creating hot spots in the head and at the cylinder at the top ring turnaround area. This thermal cycling is quite bad for head gaskets. Allowing the bypass to share the flow, or full flow if the thermostat is fully closed, (like on takeoff before it opens) is much less stressful on the engine.

An extreme case could allow the coolant to boil around the hot areas and cascade quickly to overpressure and belching of coolant even with a cold radiator. There must be flow.
 
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Bill,

No argument about theory, but most of the rotary guys don't run a thermostat, as I mentioned. (Lycs typically don't either, for the primary cooling path). The ones that do run a thermostat, don't start their takeoff run until the engine is up to temp (like we're *supposed* to do with Lycs). Sudden unbalanced heat load is one of the few things that can be really hard on a rotary (just like a Lyc).

No doubt the Mazda designers used it for precisely the reasons you state, because no one warms up their car before driving anymore.

I failed to state the reason the rotary guys do the mod. Most fear a stuck thermostat (either type can kill the engine if it sticks), so they plug the bypass & do full circulation all the time.
 
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As Bill said, you must have flow inside the engine. Certainly don't plug the bypass if you run the thermostat. It will do exactly what Bill described here.
 
Guys,

I really appreciate the comments and suggestions!

In addition to the main water outlet port from the head and the main inlet from the radiator that goes to the thermostat housing (that goes to the water pump, there are 4 other ports. Two are the inlet and outlet to the heater core. There are two more that provide water to the transmission cooler. It is worth noting that both of these returns enter the thermostat housing on the "hot" side of the thermostat. Hence both would be circulating water through the head independent of the thermostat being open - or not. I have one of the two bypasses open and functioning for exactly the reasons Bill has stated. I agree whole heartedly. Of course this is good and bad, in that they do provide hot water to circulate through the head as (they do not go through the radiator). This is good in that it helps the engine heat up fairly quickly. It is not good in that it provides hot water that is not circulated through the radiator - hence if the head is already getting water that is too high, this only makes the situation worse. I do have what would be the transmission bypass connected so it is circulating water as designed. I do not have the two lines that would typically go to the heater core connected. But it is important to know that this bypass is connected to the head exactly like the tramission bypass so it is functionally the same.


I do have suspicions about the air being trapped somewhere. I think the high delta is indicative of a water flow problem that goes way beyond the heatercore bypass lines not being connected.


I do have plans to lower the radiator and reverse the flow through the radiator. I have high hopes of getting this accomplished this weekend.

Here is a pic of the ports

http://www.halie.com/ov5.jpg

PS> I have ran with and without a thermostat and do not see any depreciable difference. Probably because once it heats up past the thermostat max opening temperature it becomes functionally irrelevant.


Thanks again.


Charlie
 
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Also just to comment a bit more about burping as RV7Charlie and others have mentioned. I have two ports the top of the engine that I keep open when filling the system. I also have clear lines coming out of these ports to feed the turbo cooling. I can see water flowing freely through these lines. Not to say this is a guarantee that there are no places where water could be trapped, but it is really hard to envision this. And honestly I think this may be my gremlin. Which is why I am going to reverse the flow and lower the radiator a bit more to try to eliminate this from happening.

We shall see....

Charlie
 
Trapped air is the #1 cause of cooling difficulties on auto engine installations. I've received many questions over the years and advised many folks on how to fix their problems. Hopefully you find the smoking gun on this one Charlie.
 
Well, the saga continues. I moved the radiator lower and made sure everything was plumbed as smooth and as direct as possible to avoid any air pockets.

It seems better but it is still not cooling properly.

I found something fascinating in my testing. The delta (difference in temp between the hot side and cold side) of the radiator increases over 2500 rpm, and lowers when below 2500. To put this another way....below 2500 rpm the delta is about 20*F. The hot side is about 150*F and the cold side is about 130*f. At this point I am not running with a thermostat to increase the chances of any trapped air pockets to move fluidly up and out of the system. But when I increase RPM up to say 3000, the hot side goes up to 190*+F and the cold side goes down to as low as 115*F. Meaning to me the flow slows down, or may be worse, stops altogether. One of the two bypass systems from the head to the thermostat housing is fully open.


I painstakingly filled the system with coolant ever so slowly burping it all along the way. I have two 1/4" ports at the top of the head that exit to the turbo and I have a line off of the top of the outlet line that goes to the radiator overflow catch can to ensure that air pockets exit at the top.


To me.....it seems like the water pump becomes ineffective above 2500 rpm. Like cavitation. But I cannot imagine how air could be trapped there, and if so, what could possibly be done to remove it.....

But for the sake of trouble shooting, I am going to try to increase the size of the port at the top of the system so if it is trapped air, it will travel up and out. We shall see.

Feel free to comment, especially if you have any experience with water cooled engines....

I get some pics if anyone wants to look at them.....

Thanks!


Charlie
 
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To be sure we're on the same page, when you say bypass, do you mean from the water pump output back to somewhere on the block, without going through the radiator? If the answer is yes, is there any chance that when the pump starts working harder at higher rpm, more of the water is taking the path of less resistance, back through the block instead of through the rad?
 
To be sure we're on the same page, when you say bypass, do you mean from the water pump output back to somewhere on the block, without going through the radiator? If the answer is yes, is there any chance that when the pump starts working harder at higher rpm, more of the water is taking the path of less resistance, back through the block instead of through the rad?

Yes it is possible. But the bypass is 1/2" and the main radiator lines are is 1,25". I could easily pinch down the bypass to test the theory.
 
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cooling gremlin

Well for those who may be following this thread I thought I would give an update. The gremlin still lives in my set up.!

Given that it appears as though the most likely culprit is trapped air, I have filled and refilled and burped this system 12 times. Each time pain staking making sure I do all I can to remove trapped air. burp it, run it with the cap off - everything. No changes.

I have ran with different thermostats and no thermostats. I have run with and without by pass hoses.

When I had a radiator with a top and bottom I reversed the hoses. Now I have a radiator that has the inlet and outlet horizontal.

Since the set up is running on a test stand with a just a radiator, it is no surprise it ends up overheating after hard runs. I think this is to be expected. It does fine at low loads and low rpm. But with the prop at full pitch and high RPM (over 20"MAP and over 3000 rpm) it overheats. This is to be expected. ( Anyone who has actual hands on experience running a water cooled engine on a test stand under load for extended time using a conventional radiator is encouraged to comment on this aspect.....)

The weird part, though, is that while the engine temp starts to creep up on heavy load.....the radiator outlet (2nd probe) starts to cool down.

In other words the engine temp probe, and the radiator outlet probe show temps that are close when - it is at low load. I.E. below 2500 rpm, and below 15" MAP. Once I start to push it the engine temp climbs and the radiator outlet probe temp starts to decline. The temperature difference I will call "Delta T". During low load the radiator outlet is 10*F lower. Above 3000 RPM and OVER 20" MAP the radiator outlet will drop as low as 155*F with the engine temp going over 200*F.


To me, it is as though there is a blockage of some kind in the system. Like an air pocket. But, if not an airpocket, then what?


1) Failing pump? Not likely

2) Pump pulley slipping? No indication of this.


3) FOD, (foreign object in the system? Who knows, would be crazy weird, but it would explain the systems.


Where to go???


I am going to try new tubes to evacuate any trapped air out of the two high spots on the block one more time.


If that does not work, I am going to install and incredibly small radiator, to see if I can keep the Delta T close even up to high temp. that would eliminate the current set up as the culprit.


I may put a thermostat back in but that really should not have anything to do with a high delta T...…


If you have any experience with running water cooled engines - especially on a test stand, I would really appreciate your thoughts....

This is certainly solvable, and in fact may be simply, but I am not there yet....

Thanks.

Charlie
 
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Do you have a diagram of your cooling setup?

From the video, it looks like a simple engine in/out, radiator in out. no overflow or bypasses. but I can't see everything from the video.

What are you using for cooling? (water, 50/50 glycol mix, Evans waterless?)

How's the radiator cap? Pressure rating? and can you check the pressure of the cooling system?

I've had weird issues when the radiator cap no longer seals properly. 1 symptom is the overflow tank will fill up and not siphon back when cooling down, but I also think the system doesn't pressurize and doesn't work quite right. If I have to remove the cap, I'll replace it with a new one.

How hot do you let it get before you shut it down?

Just a thought. (Subaru 3.0)
 
It may be trapped air, but your cavitation comment may be more accurate. I would suggest you install a restrictor in the two bypasses you have there. Maybe a 1/4" hole in each. Then install the thermostat.


Here is why, the pump is likely located up high relative to the overall cooling pool, yielding low suction head. Then to aggravate the issue, the pump is sized for a particular back pressure, forcing flow through the head.

Part of the systems' restriction is the thermostat and part is the two coolers. The result of lowering the system restriction is 1. allowing vastly increased flow, that thereby increases pump inlet velocity and lowering NPSH, net positive suction head. This can create cavitation and . . 2. excessive bypass lowers the pressure, and therefore velocity across the head/block, which would aggravate the possibility for incipient boiling.

Overall, it is likely #1 is the major part of your issue as the power is not high enough to have the #2 issue.

After getting the flows right, then we can see if you need some vapor bleed lines. Bleed lines are not unusual for highly loaded engines and will collect gas and direct back to the top tank.

If you have the thermostat housing open, can you take and post a picture to see where the bypass is located?
Worth what you paid for it.
 
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3000 rpm and 20 inches is pretty low hp, similar to going up a moderate hill in a car on the highway-perhaps around 40-50hp. I've run liquid cooled engines with props at these settings and nothing gets hot with some pretty small rads at 70F ambient temps.

The 45 degree delta is something I've never seen in all my rad testing and this pretty well must be due to the water flow being low at high rpms which points to cavitation. My deltas are typically 10-20F across the rad inlet to outlet.

Maybe install a flow meter inline and see what's happening as rpms increase.

Bill's advice on the active bleed line is good. Those have proven to be highly beneficial on Subarus which can trap air easily due to their horizontal layout. I have a .125 ID hose going from the the top of my coolant crossover pipe joining the two banks to the top of my expansion tank.
 
Do you have a diagram of your cooling setup?

From the video, it looks like a simple engine in/out, radiator in out. no overflow or bypasses. but I can't see everything from the video.

What are you using for cooling? (water, 50/50 glycol mix, Evans waterless?)

How's the radiator cap? Pressure rating? and can you check the pressure of the cooling system?

I've had weird issues when the radiator cap no longer seals properly. 1 symptom is the overflow tank will fill up and not siphon back when cooling down, but I also think the system doesn't pressurize and doesn't work quite right. If I have to remove the cap, I'll replace it with a new one.

How hot do you let it get before you shut it down?

Just a thought. (Subaru 3.0)


I am using Honda OEM coolant Type 2. It is a new cap. I shut it down when it gets over boiling. I know it is not working correctly.

It may be trapped air, but your cavitation comment may be more accurate. I would suggest you install a restrictor in the two bypasses you have there. Maybe a 1/4" hole in each. Then install the thermostat.


Here is why, the pump is likely located up high relative to the overall cooling pool, yielding low suction head. Then to aggravate the issue, the pump is sized for a particular back pressure, forcing flow through the head.

Part of the systems' restriction is the thermostat and part is the two coolers. The result of lowering the system restriction is 1. allowing vastly increased flow, that thereby increases pump inlet velocity and lowering NPSH, net positive suction head. This can create cavitation and . . 2. excessive bypass lowers the pressure, and therefore velocity across the head/block, which would aggravate the possibility for incipient boiling.

Overall, it is likely #1 is the major part of your issue as the power is not high enough to have the #2 issue.

After getting the flows right, then we can see if you need some vapor bleed lines. Bleed lines are not unusual for highly loaded engines and will collect gas and direct back to the top tank.

If you have the thermostat housing open, can you take and post a picture to see where the bypass is located?
Worth what you paid for it.

Bill, makes perfect sense. Give I had some success today, I will definitely get the thermostat on for more testing. see my comment at the end on the relative success.....I do have an extra thermostat housing with both ports that return in to it I will take a picture tomorrow.


3000 rpm and 20 inches is pretty low hp, similar to going up a moderate hill in a car on the highway-perhaps around 40-50hp. I've run liquid cooled engines with props at these settings and nothing gets hot with some pretty small rads at 70F ambient temps.

The 45 degree delta is something I've never seen in all my rad testing and this pretty well must be due to the water flow being low at high rpms which points to cavitation. My deltas are typically 10-20F across the rad inlet to outlet.

Maybe install a flow meter inline and see what's happening as rpms increase.

Bill's advice on the active bleed line is good. Those have proven to be highly beneficial on Subarus which can trap air easily due to their horizontal layout. I have a .125 ID hose going from the the top of my coolant crossover pipe joining the two banks to the top of my expansion tank.

Ross, and guys,

I did have some success today. I changed the way I was Bleeding the system. Hard to explain so I will share some pics of the set up. I have a tube exiting the high point of the block - where the OEM temp probe used to be. I added a filler cap in the block exit coolant hose and added an aftermarket overflow cap. I poured the high point tube in to the overflow bucket.

I no longer see the divergence of the delta T. But I ran out of daylight and was only able to do minor testing without the prop. But the Radiator exit temp stay relative to the coolant temp exiting the block. They were 16* to 22* apart, but the good news is they stayed relative to each other. The proof will be when I add the prop and do some load testing with it.

If it goes well I will add the thermostat back on and see if Bill's theory of flow works well for my set up. I hope it does!!!

Here is a pic of the overflow and bleed line set up.

http://www.halie.com/o76.jpg

(I wish I could get a real pic to show up and not just a link. I am using halie web hosting).

Here is a link to both radiator lines and the HOT temp and the COLD temp.

http://www.halie.com/o7y.jpg

I will get a pic of the inside of the thermostat housing (I have an extra one) to show where the bypass enters. It enters behind the thermostat and of course serves to warm up the block uniformly before the thermostat opens up.

I hate to be a bother, but I really appreciate all the help. I know this will get resolved,

Thanks!

Charlie
 
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Cooling

Dont know about cooling on eng stand, but I followed Ross from SDS info on
ducting too and from rad, never cooling problem, PROPER DUCTING MAKES ALL
DIFFERENCE IN THE WORLD ! Tom
 
Tomcat

Yes we're fortunate to have Ross' knowledge and expertise to draw from. He has been super helpful to me for years and the SDSEFI is an excellent product.

Do you have a alternative engine in your -4?

Charlie
 
To be sure we're on the same page, when you say bypass, do you mean from the water pump output back to somewhere on the block, without going through the radiator? If the answer is yes, is there any chance that when the pump starts working harder at higher rpm, more of the water is taking the path of less resistance, back through the block instead of through the rad?

Sorry I did not get back to your questions sooner....

There are two bypasses on this engine. One for the Heater Core, and one for the transmission cooler. They are both connected internally in the block. I am using one of them. They pass water through the engine even when the thermostat is closed. It is only about a 1/2" in diameter so while it is important to make sure the head does not develop hot spots before the thermostat opens.... I don't think it is as significant at this point because I am not currently using a thermostat. (I plan to put one back in after more testing).

Due to some progress recently I am cautiously optimistic it was trapped air but more testing is needed before I really feel comfortable I know what is the full cause of the issues.

Thanks.!

Charlie
 
Yes I had totally stock 2.5 imprezza subie, 165 hp,with SDS and 950lbs empty weight, turned out to be a rocket ship, way to much for someone my age, so in
Process building zenith 701, definitely use auto eng in it ! It went to good home
in S. America . Tom
 
Yes I had totally stock 2.5 imprezza subie, 165 hp,with SDS and 950lbs empty weight, turned out to be a rocket ship, way to much for someone my age, so in
Process building zenith 701, definitely use auto eng in it ! It went to good home
in S. America . Tom


I would really like to learn more about the radiator set up in it do you have pictures you can share? Were you happy with it ?

Charlie
 
SOLVED!!!! (cooling gremlin)

My cooling troubles are SOLVED!

I do believe that 90% of it was just like Ross and others suggested, BUBBLES! Trapped air.

Super thankful to Ross, Bill, Andy, Jon, Jeff, RV7charlie and all who gave advice and support.


I ran it at 4800 rpm and about 28" MAP - for more than 10 minutes, which is kind of harry on a teststand in my parking lot at home.....and it held at 185*F outlet, and about 159*F inlet temp. This was with NO thermostat and the bypass open.

I will add the turbo back on and see how that goes. I have read different theories on the routing of turbo water cooling lines. These are on the sides of the turbo housing. Some say both should point up to allow water to pool to aid in cooling after shut down, some say one up and one down and some say both down.

Ross, if you are reading this, I know you have a ton of experience at this. what is yoru advice on the turbo water cooling lines. I have mine on banjo fittings. So they either have to point up or down. I have had them both pointing up and this does allow for water to "rest" in the turbo housing after shut down. But since my turbo is really up high on the block, they have a tendency to encourage air to get trapped in the top after shutdown. I can try to find a pic to show you what I mean.....

Charlie
 
My cooling troubles are SOLVED!

I do believe that 90% of it was just like Ross and others suggested, BUBBLES! Trapped air.

Super thankful to Ross, Bill, Andy, Jon, Jeff, RV7charlie and all who gave advice and support.


I ran it at 4800 rpm and about 28" MAP - for more than 10 minutes, which is kind of harry on a teststand in my parking lot at home.....and it held at 185*F outlet, and about 159*F inlet temp. This was with NO thermostat and the bypass open.

I will add the turbo back on and see how that goes. I have read different theories on the routing of turbo water cooling lines. These are on the sides of the turbo housing. Some say both should point up to allow water to pool to aid in cooling after shut down, some say one up and one down and some say both down.

Ross, if you are reading this, I know you have a ton of experience at this. what is yoru advice on the turbo water cooling lines. I have mine on banjo fittings. So they either have to point up or down. I have had them both pointing up and this does allow for water to "rest" in the turbo housing after shut down. But since my turbo is really up high on the block, they have a tendency to encourage air to get trapped in the top after shutdown. I can try to find a pic to show you what I mean.....

Charlie

Glad you solved it and those temps look much like mine now.

If this is a journal bearing turbo, I'd leave the water lines disconnected and just run a good synthetic oil like Mobil 1. They are a liability in my experience.

If it's a BB center section, you need the water lines. A slight up slope in the fittings from feed to exit should help move air through and thermo syphon water through the center section.
 
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turbo cooling

Ross,

I have used mobil synthetic from the beginning. This turbo is a journal, as I consider myself still in the proof-of-concept stage.

Thanks again, great support and help as always.

Charlie
 
As a follow up....my next step is to install the turbo, and then a thermostat.

LESSON LEARNED: To all who may venture on a project like this...It is imperative to take a lot of extra time and effort to set up a system that will ensure all the air bubbles are out of the cooling system. I am amazed that it took hours, and more importantly, a weird (to me) set up where the top line could feel back to an open funnel to allow bubbles to evacuate out of the system as it was running.

ALSO, I think it is very important to have a temp probe to test the coolant temp as it leaves the block/head AND another one to test the temp of the coolant as it reenters the engine from the radiator. If I had not done this I would have missed the fact that these temps were diverging instead moving up lock-step as the water getst hotter. I will definitely keep a dual coolant gauge on my plane.

I think a catch-can style auto bleeding set up may be in order. I have some ideals....

Charlie
 
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ENGINE MOUNT (Early Stage)

I am very happy with the progress of the engine testing. The cooling was my biggest challenge. I was finally able to evacuate the air and things are running quite well now, considering it is on a test stand with a small radiator.

I am beginning the next phase which is to build an engine mount. Below is a link to a picture of the mount in the jig. It is chromoly tubing. I will be working to fine tune the fit and migrate it over to the engine and tack weld it and then mate it up to the airframe and tack weld that.

Once it is fully tack welded I will install the custom cowling and cross my fingers and hope for a good fit.

http://www.halie.com/o7t.jpg I would appreciate someone to let me know that the link I provided actually opens up for you OK.

Also, for those who have not seen a video of the engine running on the test stand, below is a link of a video I made today of it running at 4000 RPM at 30" of MAP using a 68" 3 bladed warp drive prop and of course the SDS EFI. It is up-fitting with a T3/T4 Turbo and the Viking Aircraft Engine gear box. Sorry for the sunlight washing out the pic when I walk around the engine, it was late in the day.

https://youtu.be/YEKzTym9DaM

(hope the link works for you all.).

Thanks for all the support and encouragement.

Charlie
 
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The photo shows up fine. Lots of time spent fitting those tubes. I remember this step well on my 2 planes.

The power setting in the video is about where I run my Sube in cruise- 25 inches and 4200 rpm. The Honda sounds nice and smooth there. Keep up the good work. :)
 
The photo shows up fine. Lots of time spent fitting those tubes. I remember this step well on my 2 planes.

The power setting in the video is about where I run my Sube in cruise- 25 inches and 4200 rpm. The Honda sounds nice and smooth there. Keep up the good work. :)

Thanks Ross. Yes, I will feel a bit of relief when I take it out of jig and try the fit to the engine and airframe. I expect a few minor tweaks and that is why it will be tack welded for the trial fit.

It will be a big day for me when I can hear and see that engine run while I am sitting in the plane!

Thanks

Charlie
 
Definitely orient for the coolant to boil out.

My cooling troubles are SOLVED!

I will add the turbo back on and see how that goes. I have read different theories on the routing of turbo water cooling lines. These are on the sides of the turbo housing. Some say both should point up to allow water to pool to aid in cooling after shut down, some say one up and one down and some say both down.

Charlie

A friend of mine has a patent on the pooling shelf design. Our diesel engines got to be tightly "cowled" due to noise regs and was coking the oil. I remember our discussions about that when he had his idea list. The boiling of the coolant in that shelf dramatically dropped the temperatures of the center housing and out to the seals. All turbos should be made this way now, so pay attention to that orientation.
 
Most turbos have an option for a water cooled center section and they are a must when running ball bearings. My 40 years experience with journal bearing turbos is you don't need the water if you run Mobil 1 oil and don't shut the engine down with the turbine housing red hot. Let the engine run slow and idle for a minute or so as you finish your trip.

I've ice and road raced them (16 years) driven them on the street since 1978 to the tune of a million km+ and flown them for 15 years. Never had a bearing or seal failure yet with Mobil 1 in any of them.

The water lines are a liability in an aircraft IMO. More things to fail (and maybe lose your coolant), more weight, more complexity. We don't run water cooled turbos on the Reno stuff since there is no water available and that is a really severe test with EGTs up to 1800F and pushing the units right near their N1 limits.
 
Most turbos have an option for a water cooled center section and they are a must when running ball bearings. My 40 years experience with journal bearing turbos is you don't need the water if you run Mobil 1 oil and don't shut the engine down with the turbine housing red hot. Let the engine run slow and idle for a minute or so as you finish your trip.

I've ice and road raced them (16 years) driven them on the street since 1978 to the tune of a million km+ and flown them for 15 years. Never had a bearing or seal failure yet with Mobil 1 in any of them.

The water lines are a liability in an aircraft IMO. More things to fail (and maybe lose your coolant), more weight, more complexity. We don't run water cooled turbos on the Reno stuff since there is no water available and that is a really severe test with EGTs up to 1800F and pushing the units right near their N1 limits.

I'll defer to your experience, Ross. Although, for validation of a good process, I might recommend a thermocouple on the housing to confirm this installation and cool down phase. Mobil 1 will tolerate much higher temps w/o coking.
 
I'll defer to your experience, Ross. Although, for validation of a good process, I might recommend a thermocouple on the housing to confirm this installation and cool down phase. Mobil 1 will tolerate much higher temps w/o coking.

Yes, the main key to not getting coking failures on the bearings and turbine end seals is the synthetic oil and that 1 minute of lower rpms and load before shutdown. Andy also runs synthetic automotive oil in his Race #30 Lancair which won Sport Class Gold this year.
 
engine mount update

Well the engine mount design and construction has been "fun". I am getting good at making "fish-mouth" ends and I actually enjoy the tig work.

I would like to use the cowl I made but in order to use this, I have to use at least a 6" extension, and 8" would give me freedom to work with.

I am using a Viking Aircraft Engine gearbox, and I am waiting to hear back from them on this idea.

Charlie R.
 
Charlie,I got ducting measurements and info from Ross, I believe the amount
of testing Ross did showed importance of proper ducts to get optimum cooling
on any aircraft conversion.It showed you could use relatively small rad and the
pipes to and from rad . Such great company and person, I am sure when you
need he would share ?..Tomcatrv4
 
Tomcat

Thanks for the tip on cooling/ducting. Jeff Caplans shared the link to Ross' website where he shared detailed photos and instructions on the cooling ducting he did for his RV6a. It is very helpful.

I plan to do something very similar, but probably out of aluminum and not wood. Ross has more patience in sanding that I have. :)

I did a quick check and did not find it on his website but if anyone is interested I could look harder.

May be we can ask Ross to put a search box on his website??? (Or may be it is there and I missed it, that is possible too!)
 
Yes, the main key to not getting coking failures on the bearings and turbine end seals is the synthetic oil and that 1 minute of lower rpms and load before shutdown. Andy also runs synthetic automotive oil in his Race #30 Lancair which won Sport Class Gold this year.

I was having problems in my Audi with the turbo seals, excessive smoke, and oil consumption. Was using Mobil 1 full synthetic until an oil expert advised to not run a full-synthetic oil. Smoking and coking problems stopped immediately going to a semi-synthetic oil of the same weight. Oil consumption was reduced 90%. I was shocked because I was always under the impression synthetics were superior.
 
I was having problems in my Audi with the turbo seals, excessive smoke, and oil consumption. Was using Mobil 1 full synthetic until an oil expert advised to not run a full-synthetic oil. Smoking and coking problems stopped immediately going to a semi-synthetic oil of the same weight. Oil consumption was reduced 90%. I was shocked because I was always under the impression synthetics were superior.

I've used Mobil 1 since the early eighties and fed it to all my many turbo engines I've owned over the years (dozens) and many, many thousands of hours collectively. Never a lubrication failure in the engines or turbos or coking issues. I used to overhaul turbos for a living as well. Never seen coking with Mobil 1 but seen lots with conventional oils. Look at the coking and flash points for it compared to other oils.

My high time Garrett turbo in our shop car had over 5000 hard hours on it using Mobil 1. Turbo never touched in 19 years, never smoked, bearings still tight.

Early Audis with KKK units were well known for turbine ring sealing issues and smoking. I fixed many of them back in the day. Bad design with too much oil being shot at the ring seal. I plugged one of the oil feed holes on these and problems never returned. One of these K27s (to fit Audi) on a Toyota custom installation I did went on for over 15 years and several owners and thousands of hours, no bearing, seal or smoking issues- all on Mobil one.

Hard to believe an oil with superior high temperature anti coking properties was the cause of your smoking issue.
 
You can see most of my rad development stuff near the end of these 2 pages:

http://www.sdsefi.com/rv16.htm

http://www.sdsefi.com/rv17.htm

There are so many separate pages on our site, it's hard to build a search feature at this point. You can try the Control F command on each page to find something specific.

Ross, thanks for posting the links.....

Anyone who has a interest to venture in to the power plant side of aircraft building will benefit greatly from the huge source of information that you provide on your website.

Thanks again.

Charlie
 
I'll try to dig up the actual size/area/volume specifics on my rad installation and post them here later today when I get some time.
 
This is from another forum post:

Inlet area 29.5 in2
closed outlet area 16.8 in2
open outlet area 51.5 in2
radiator face area 118.8 in2
rad core volume 267.3 in3
rad core depth 2.25 in
tube dimensions .080 x 1.00, 2 rows
tube spacing .4375in
fin density 14/in

total duct length 49 inches
coolant flow is horizontal

The duct uses a central, vertical splitter and two horizontal guide vanes to turn the air without separation (shown after tuft testing). Main divergent duct angle is <7 degrees.

Rad tanks are not exposed to the airstream, only the core matrix.

Core is fed by .75 tubing for coolant, run a standard OEM thermostat with single .125 inch safety hole in base. Rad is perpendicular to the freestream.

Takeoff power is about 160hp at 35 inches and 4600 rpm.

I was able to idle at 1000 engine rpm for 45 minutes at an OAT of +27C with coolant stabilizing at 90C. There are no supplemental fans fitted, just the big one out front...

Coolant mix is 70% H2O, 30% Prestone Ethylene glycol and a tiny percentage of Redline Water Wetter.

Duct inlet lip radius is .125in.

I used some ideas from Russell Sherwood's SARL championship winning Subaru EG33 powered Glasair. He had very similar experiences and design features to what I ended up with. He uses only 32 in2 of inlet area for 230hp and he says he will reduce this further as it is still bigger than required. He can close his exit door down to I believe 22 in2 at high speed cruise. Ground cooling is no issue up to 35C as long as aircraft is not pointed downwind.

What we have learned so far actually flying these installations is:

1. That you don't need huge rad piping for the coolant. "Experts" told me my engine would not cool with 3/4 tubing.

2. You don't need huge rad face area or volumes.

3. You don't need huge inlet areas or large inlet lip radii even in climb. Again, "Experts" said we'd never cool.

We have 3 flying aircraft using similar designs and ratios to this per installed hp. All 3 cool very well under all conditions having accumulated over 1100 flight hours to date (2014).
 
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Ross,

Your last post detailing the specs on your radiator/ducting set up is invaluable to those of us who venture down the water-cooled engine installation journey, thank you!

I know you live near Santa Claus, but that said, I am curious how often you actually vary the outlet opening with the push-pull cable?

It seems as though the ability to vary the outlet opening is tantamount to the function of the thermostat.

Charlie
 
The cooling is so good, I leave it closed most of the time. I'll open it on the ground during a long hold or on a long climb on a hot day.

In the winter, I block off 50% of the rad with a foam insert and block off 30% of the heater core face as well. The door remains closed all time in the winter even with these things done. On final, it will still drop to 140F.

The heater core is in the thermostat loop and provides a lot of cooling. The thermostat does not have control over that water flow
 
The cooling is so good, I leave it closed most of the time. I'll open it on the ground during a long hold or on a long climb on a hot day.

In the winter, I block off 50% of the rad with a foam insert and block off 30% of the heater core face as well. The door remains closed all time in the winter even with these things done. On final, it will still drop to 140F.

The heater core is in the thermostat loop and provides a lot of cooling. The thermostat does not have control over that water flow

Ross,

This really proves the design is certainly more than sufficient.

To clarify.....you said the heater core is in the thermostat loop...but then said the thermostat does not have control over that loop. Did you mean to say it this way? Or did you mean to say the thermostat is not in the heater core loop....

Charlie
 
Most auto engines for the last 30 years have the heater core flowing coolant all the time with no valve in the flow like the old days-they just mix hot and cold air with the heater control. This means the heater core coolant flow bypasses the thermostat all the time.

I take hot air off about 30% of the core through twin 2 inch SCAT hoses and the rest bypasses so the core offers a bit more cooling capacity for the engine at all times.

I don't use any other bypass hose in my setup for the thermostat. The heater core in plumbed with 5/8 hose.

On days below -10C, the heater core alone is sufficient to cool the engine in cruise below 25 inches. The thermostat never opens. The core is fed by a single ram duct via 3" SCAT hose and a difuser with internal guide vanes to spread the flow over the whole core face. The core is 8 X 8 X 1.625
 
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Most auto engines for the last 30 years have the heater core flowing coolant all the time with no valve in the flow like the old days-they just mix hot and cold air with the heater control. This means the heater core coolant flow bypasses the thermostat all the time.

I take hot air off about 30% of the core through twin 2 inch SCAT hoses and the rest bypasses so the core offers a bit more cooling capacity for the engine at all times.

I don't use any other bypass hose in my setup for the thermostat. The heater core in plumbed with 5/8 hose.

On days below -10C, the heater core alone is sufficient to cool the engine in cruise below 25 inches. The thermostat never opens. The core is fed by a single ram duct via 3" SCAT hose and a difuser with internal guide vanes to spread the flow over the whole core face. The core is 8 X 8 X 1.625

Ross, yes, what you describe is exactly how the R18 Honda engine I am using is set up.

The only part that threw me was when you wrote that.. "the heater core is in the thermostat loop". But I think that was a mis-statement, and that you meant to write the "heater core is in the bypass loop" . I apologize if it sounds like I am being too picky, I just wanted it clarified in case others who read this may have taken it the way it was written. (or may be I understand it wrong!)

Thank you.

Charlie
 
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The heater core provides the bypass flow to activate the thermostat when it's closed. The heater core fitting aims directly at the T stat bulb on my Subaru. No other bypass hose is used.

With the T stat on the suction side of water pump, you must have some sort of bypass or it will never open as some folks have found out the hard way when they plugged it off or left the heater core out of their installation.

My installation has a big enough heater core to fly at low cruise without over heating even if the T stat was stuck closed which gives some more piece of mind.
 
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