Turbo Temp/Lower pressure side heat - Optimization
Posted: Fri Sep 22, 2023 2:08 pm
by tps8903
Hey Guys,
When Sonex was troubleshooting the turbo failures, one of the 4 reasons for failure was oil coke on the bearing. Step one in the test results was to remove the turbo blanket, which deceased the bearing block temperature.
It was determined that the first set of air cool mods didn’t work enough so the liquid cooling add on was completed.
My question, at risk of having someone or the factory jump down my throat. Has there been any testing, or does anyone here have any experience with the liquid cooling AND the turbo blanket?
I only ask, because without the turbo blanket the ambient temp of the low pressure area, specifically next to the turbo gets HOT! Even with the stainless shield. I operate in Central Florida. My thought is I can dump cool air back there off the NACA, but then I am hurting the pressure diferential of my engine cooling (which works well). Or, I can blanket the turbo and force the heat out through yhe exhaust pipe.
There is no doubt I’ll achieve the temperature goals with a quality blanket, I’m just not sure if I’ll exceed the 250F bearing back temp.
I do have a sensor rigged for the bearing block. I’ll likely test it myself if no one has real world data.
The reason I ask is that I’ve had 3 ignition failures in under 50 hours due to heat, I suspect off the turbo. So my goal is to cool it down back there without sacrificing engine cooling.
Thoughts?
Re: Turbo Liquid Cooling Test Info
Posted: Sat Sep 23, 2023 5:22 pm
by tps8903
I’ll take the lack of replies as no one has tried this yet.
As an update to my OP. I’ve installed a Turbo blanket and made sure exhaust wrap is seamless. I already had a probe attached to the thermostat for the liquid cooling to monitor the bearing block temperature (CHT#5). I installed another probe near the ignition coils to check ambient temperature (CHT#6).
I deleted the cabin heat to stop dumping useless air on the low pressure side. I already had the front hole on the cowling plugged (oil temps have never been a problem). I also deleted the cold air induction off the NACA and as a result the carb heat. Plane lost 3 lbs in the process. The cabin heat was obviously dumping wasted air. The cold air induction was sealed. But the nature of the design would allow excess air to travel backwards through the carb heat to prevent RAM air on the aerocarb. With a turbo I feel like cold air induction and carb heat are useless. I can pull 43inhg if I want to…
There are 4 paths to the low pressure side. Through the engine. Through 2 NACA vents and through the front cowling hole. So basically I’m starting with 1 restricted NACA vent for now, and will open others if needed. The restricted NACA vent is a blast tube for the coils for now. Trying to create a boundary layer of cold air between them and the turbo.
I also installed 4" vents above the turbo.
I bought a manometer to get an understanding of the pressure difference in the cowling, I’m going to route the tubes out the cabin NACA and in the cowl NACA with the blast tube and use duck tape to secure the 20" or so outside of the plane.
My exit area on the cowling is 51sqin. So it should be okay. But ultimately this is to find out if I need more. It’s currently 12.5" wide. But if already considered stretching it to 18" or so.
I’m not sure if the 4" vents will draw air from the back of the cowling. I’m hoping they will. I need some airflow near the turbo. Any ideas on what I can do wo see if the is air being drawn through the top vents?
My goal in all of this is to maintain my good CHT and Oil temps (which I already have, while lowering the ambient temp behind the engine which is wreaking havoc on the ignitions. All while not cooking the turbo on shut down.
Let the experiments begin…
Re: Turbo Liquid Cooling Test Info
Posted: Sat Sep 23, 2023 5:56 pm
by Bryan Cotton
Cool! This optimizing is equal parts fun and hassle.
Re: Turbo Liquid Cooling Test Info
Posted: Sat Sep 23, 2023 7:23 pm
by tps8903
Bryan Cotton wrote:Cool! This optimizing is equal parts fun and hassle.
I also bought the Model B side vents. I’m going to do a test flight without them, with the manometer setup. Then install them and try again.
I was reading on here that the factory was concerned that having the bottom and side vents could rob each other of efficiency. I think worse case the side vents will add overall cooling, they may just be less efficient than they might be as a stand alone. We will find out for sure.
I’ll post results here once I have data.
I’ll have data on cooling the turbo with blanket on and liquid cooling installed.
Cowling ambient temps.
Pressure differential with lower exit and Model B exits
Pressure deiffential dumping various qualities of NACA air in to the low pressure side.
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Sat Sep 23, 2023 9:24 pm
by pfhoeycfi
I added deflectors to my B exits which solved my heat issues. I took manometer readings with and without and the PD from inlet to outlet Increased significantly with deflectors. Not quite the same issue but something to consider nevertheless.
Peter
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Sat Sep 23, 2023 9:58 pm
by tps8903
pfhoeycfi wrote:I added deflectors to my B exits which solved my heat issues. I took manometer readings with and without and the PD from inlet to outlet Increased significantly with deflectors. Not quite the same issue but something to consider nevertheless.
Peter
Excellent info Peter. Do you have the dimensions and or pictures etc of those deflectors?
Thanks
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Sun Sep 24, 2023 7:04 pm
by pfhoeycfi
tps8903 wrote:
pfhoeycfi wrote:I added deflectors to my B exits which solved my heat issues. I took manometer readings with and without and the PD from inlet to outlet Increased significantly with deflectors. Not quite the same issue but something to consider nevertheless.
PeterExcellent info Peter. Do you have the dimensions and or pictures etc of those deflectors?
Thanks
The flange w the screws is 1/2 wide, the angle is 30, the height off the cowling is approx 3/4". I closed the ends.
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Sun Sep 24, 2023 7:09 pm
by pfhoeycfi
Pic
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Sun Sep 24, 2023 8:32 pm
by tps8903
pfhoeycfi wrote:Pic
Fantastic. I made a set today. I didn’t close the ends. I made the 30° but made them a tiny bit longer so they are 7/8" up. I’m Mounting them inside home ever with epoxy etc.
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Mon Sep 25, 2023 3:22 pm
by tps8903
Well today I installed the Turbo blanket.
OAT was 91F as sea level. I flew at 2000’ it was 87F at that altitude.
It performed as advertised. I don’t know what the ambient temp of my cowling was before, but the paint would bubble in places. Today it was noticeably cooler.
During flight the ambient cowling temp at the center of the firewall next to the #2/#4 coil never went above 121F. I do have a single blast tube near the coils.
Shut down was a success as well. Max bearing block temp was 199F 5 minutes after shut down. Then trended down for the next 20 minutes. Ambient cowling maxed at
161F at 15 minutes.
Oil Temp in flight stabilized at 197F.
At 35" MAP #3 was my hottest at 370F. I don’t know why it’s running hotter than the rest at this point. At 30" MAP it’s 365F.
My EGT #3 also appears to have failed. It read about 450F the entire flight. It was also reading different on shutdown. All the other ones read about 200F when it was heat soaking. #3 read 140F. So I suspect it’s gone bad.
CHT Max continuous 35" MAP
#1 350
#2 335
#3 370
#4 335
Next step is to add the B vents with lip per suggestions.
Lessons learned so far.
Turbo blankets lower ambient cowling temp
Turbo blankets will not affect the shut down temps if liquid cooling is installed.
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Mon Oct 02, 2023 10:08 am
by tps8903
B Vents installed and primed. Paint tomorrow then test flight.
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Wed Oct 04, 2023 1:06 pm
by tps8903
Installed
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Wed Oct 04, 2023 1:17 pm
by tps8903
Test results with B vents and deflectors.
OAT 88F
CHT Cruise 35" MAP 340-365F
CHT Climb out 40" MAP to 1000agl Max 370F approx 40F reduction on CHT 3
Climb 35" MAP at 100mph max CHT 380F. I was unable to keep below 410F before.
Max ambient cowl temp 110F.
Max oil temp 171F.
My configuration is 1 NACA blocked. Will likely reinstall cold induction and carb heat with that vent. 1 NACA blast tube to firewall accesories to keep cool. Front smile open. Turbo blanket on. Liquid turbo cooling for shut down. B vents with deflectors. Bottom vent.
I can now climb continuous at 35" MAP without going over 380F on CHT 3. Next test I will climb at 35" to 6000+’ to see if that holds. Oil Temp is 20F cooler and ambient cowl temp is 110F, about 20F over OAT. I think I finally have the cooling where I want it. To summarize, no change in cruise CHT, which was already good. But great improvement in climbing cooling, which was my issue. Also improvement in cowl ambient temps.
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Wed Oct 04, 2023 2:09 pm
by Bryan Cotton
Chris,
That’s cool! Is there any noticable difference in cruise speed? I have a set of B exits but was talked out of putting them in addition to my stock A model bottom exits. Climb in high temperatures is still a killer.
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Wed Oct 04, 2023 2:40 pm
by tps8903
Bryan Cotton wrote:Chris,
That’s cool! Is there any noticable difference in cruise speed? I have a set of B exits but was talked out of putting them in addition to my stock A model bottom exits. Climb in high temperatures is still a killer.
Cool indeed!
I didn’t notice any appreciable difference in cruise speed. If there is a difference, I wasn’t able to detect it. That’s using the highly scientific TAR (Thats about Right) Method.
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Thu Oct 05, 2023 9:47 am
by builderflyer
tps8903 wrote:Test results with B vents and
My configuration is 1 NACA blocked.ambient cowl temp is 110F, about 20F over OAT. .
Not flying behind an Aerovee but these are the numbers that really jumped out at me. My ambient cowl temp is typically 70F above OAT. Your number sounds almost too good to be true. I wonder what others have seen here for this differential.
Art,Sonex taildragger #95,Jabiru 3300 #261
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Thu Oct 05, 2023 11:44 am
by Bryan Cotton
I’ve never measured mine, but the cowl is too hot to leave my hand on it after flying.
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Thu Oct 05, 2023 7:22 pm
by tps8903
builderflyer wrote:
tps8903 wrote:Test results with B vents and
My configuration is 1 NACA blocked.ambient cowl temp is 110F, about 20F over OAT. .
Not flying behind an Aerovee but these are the numbers that really jumped out at me. My ambient cowl temp is typically 70F above OAT. Your number sounds almost too good to be true. I wonder what others have seen here for this differential.
Art,Sonex taildragger #95,Jabiru 3300 #261
I don’t know what it use to be. But like Bryan said it use to be too hot to touch. I would also get the occasional paint blister.
I have so much exit space now I can afford to dump a 2" NACA into the firewall area to keep things cool. I put my hand on the cowl after the flight, and for the first time it was hot, but didn’t hurt my hand. I definitely can leave my hand on the cowl.
It should read 30° over OAT. Typo. It was a mid 80 day and cowl tamp was about 110-120
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Thu Oct 05, 2023 7:24 pm
by tps8903
I’ll do a longer flight when I get back from out west and post results. Including an extended climb report.
Re: Turbo Temp/Lower pressure side heat - Optimization
Posted: Thu Oct 19, 2023 8:20 pm
by tps8903
Today I did a 2.4 hour test of my new setup.
I’m please to announce that everything is working 100%.
Today I climbed at 35" MAP and 105mph up to 8000’ msl from 70’ msl on a 83F day. At 8000’ the hottest cylinders were just below 370F. The cool cylinders just above 350F. Oil Temp was 176F peak and cowl firewall temp never got over 120F.
I ran the engine at 35" MAP for 2 solid hours and everything was green. When I landed for fuel I put my hand on the cowl and left it there, warm, but not hot.
My setup is a quality turbo blanket, exhaust wrap, Legacy bottom vent with B side vents with 1" deflectors. 4" round top vents and 1 NACA vent (2") blasting cool air on the coils. Front cowl smile open and the NACA vent on the left side is currently still blocked. I may reinstall my cold air induction and carb heat on that side, but for now it’s working great.
I did a IAS to CAS test on the flight back. Today was a zero wind day in Central Florida, so that made it super easy and consistent. My IAS reads 2mph low in the 130-150 mph range.
32.5" MAP gets me 153 mph TAS at 3600’ (5665’ DA)
35" MAP gets me 164 mph TAS at 3600’. (5665’ DA)
Environmental. 30.12inhg, 28C 3500 msl
Re: Turbo Temp/Lower pressure side heat - Optimization
by OneTallShort » Fri Oct 20, 2023 9:59 am
Chris,
This is great data. Can you clarify where the round hole on the nose goes? Would you use that (more simple) location again vs. a side NACA inlet as a blast tube inlet?
I assume you have the top mounted oil cooler?
With everything in place, I’m wondering if you could run some tests with the top 4" round vents blocked (one or both) to see if they are really needed.
Would you do that air dam again on the exhaust pipe exit? I assume you were hoping to make sure that hole wasn’t presurizing the lower cowl.
And just to confirm, this is an A model cowl with the B vents. Right?
Thanks for all your testing. I’ve been wondering a number of these same issues as I still have to finish my cowl on my A model. I already have the turbo with liquid system installed and I own the b vents..
Gregg Short
Sonex-A 715
Burbank, OH
330.465.7531
gregg at gshort com