High CHT temps on 0-340

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BDA
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Location: Kenai Alaska

Re: High CHT temps on 0-340

Post by BDA »

Installed 3” NACA duct (amazon) in cowling and ducted to oil cooler and tested today.

Almost an hour at 2450 rpm during hotest part of the day (60s) and oil temp topped out around 210-215*F

CHT were 410*F

2,000 rpm temps were 330.
2,200 rpm were 365

This is the best I have seen so far. Until now I have not been able to sustain 2450 without exceeding 430*.

I would like another 10* or so on oil and CHT, so there is more work to do.
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SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
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BDA
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Re: High CHT temps on 0-340

Post by BDA »

At the recomendation of A&P I reduced timing advance on Pmags to keep CHTs below 400*. This worked very well (370).
But I lost performance. Take off lengths were double (prop different too).
So I added more vents to cowl and gained more cooling.
This Titan cowling from the factory does not have a large enough exit hole at the bottom.
I am close, but will add vents to the sides to reduce further.
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BDA
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Re: High CHT temps on 0-340

Post by BDA »

Update on the 0-340 cooling issues.
Doesn't matter what I did to the cowling, it wasn't enough.

Finally re-jetted carburetor much richer, and made custom pushrod tube seals in the plenums. I can now climb at full throttle, cruise and lean as needed.

I will still hit 400* on a hot (Alaska) day in a long climb.
My Oil temps are still high - working on that.
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stede52
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Re: High CHT temps on 0-340

Post by stede52 »

BDA,
Sorry to hear you are still having heating issues with the 340. If you are interested I can sent you some firewall forward docs to show the plenum installation/design and new oil cooler and location which solved the overheating issue on the Carboncubs Titan 340. It might give you some ideas for situation. My issue on my cub is that it's normally too cold, so I know the system works. I've enclosed a pic of the Carboncub plenum/oil cooler config.
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BlainS
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Re: High CHT temps on 0-340

Post by BlainS »

IMG_0001.jpeg
Here is my answer. Vans baffles. Cooling is a known issue so I decided to try something else.
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stede52
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Re: High CHT temps on 0-340

Post by stede52 »

In the event you want to do more experimenting, the one thing that made a huge difference in cooling the oil on the Carboncub was the repositioning of the oil cooler to the top of the engine under the plenum where it gets direct ram air. Good luck, These low and slow airplanes can be hard to cool, however, much more fun to fly. :D
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BlainS
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Re: High CHT temps on 0-340

Post by BlainS »

That reminds me of early Volkswagens that had the cooler over , I think #3. Guess which cylinder cooked first.
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BDA
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Re: High CHT temps on 0-340

Post by BDA »

Stede, that was where I originally put the oil cooler (cooling hose off the back of the left plenum). I blocked that off to try to cool the cylinders better.
BUT - that didn't work - and now that the left bank is cooler than the right, I will try that again.
I like the full top plenum idea - but it seems redundant with the top cowl, extra weight. The Plenum / cowl that Carbon Concepts uses - all in one.
Thanks for the ideas.
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BlainS
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Re: High CHT temps on 0-340

Post by BlainS »

Hey Shawn, I’m wondering about a cross connection between the 2 sides to equalize flow. I remember watching a video at Catto’s shop showing the different flow patterns from right and left air intakes. Maybe a couple of 3” scat tubes? Also Troy’s design doesn’t capture the air on the bottom of the cylinders. Slowing down the flow there might give it more contact time to increase heat transfer.
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SheepdogRD
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Re: High CHT temps on 0-340

Post by SheepdogRD »

Some interesting discussion about this over on HomeBuilt Airplanes: https://www.homebuiltairplanes.com/foru ... ion.49155/.
Richard Holtz
Highlander N570L -- Ms. Tonka -- in gestation

If just enough is really good, then too much ought to be perfect.
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