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Titan XIO 360 CHT Concerns

Tcheairs

Well Known Member
My newly acquired RV 7A equipped with the xio360 (130 hrs on engine) is showing between 420 and 435 degrees CHT on climbout even with full rich mixture and a cruise climb of 120 to 130 KIAS to altitude. At altitude (8000ft on a standard day) the CHTs will cool down to 350-375. Leaning doesn't seem to affect the CHTs much in cruise. I'm a big bore Continental transplant and I was able to manage Chts easily with cruise climb techniques and mixture control.

Am I in danger of damaging my engine with these high CHTs in climb? I'm worried about what I'm going to see when it really gets hot around here this summer.
 
Most likely not as much an engine issue, but cowl/baffling.

Some searching here will help, but basically air is stuffed in the top, and the goal is to easily exit the bottom. I have seen planes with no rubber seal on intake (vertical induction), allowing the lower to be pressurized. Leaking baffles on top, or someone got extra zealous making the cowl tight around the exhaust exit which as built is where 90% of the air needs to exit.

We have installed cowl flaps for 2 rv9's from Anti-splat for customers and that helped both of them. Many things to look at in how it was built first.
 
It is my opinion that A models suffer from exit air blockage due to the gear weldments and the lack of the exit smoothing "bump". Higher AOAs just makes it worse.
I added louvers to my bottom cowl, which improved things, but I still have to manage temps when heavy and hot.
Anything above 425 and I'm leveling off to get some airflow.

I have an TMX-O-360 with half EI and a FP prop.
 
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I would appreciate additional information about the installation of cowl flaps. They were essential on my V35 Bonanza. Photos? etc. I'll do a search on the forum for cowl vent/flap additions..Thanks
 
IMHO cowl flaps are a bandaid for this. I would start with baffling quality and sealing up open areas. Many goods posts here on that subject. Whole lot of folks with 360's that can climb at 120 with CHTs 400 or lower without louvers or cowl flaps.

Also do research on timing. The Pmag can get very aggressive once above 5000' and cause CHT issues.

I have a 320 (160HP) A model and on the hottest days, just ticks over 405 at the very top of the climb (much lower below 5000'). In my case it is the timing that keeps advancing with altitude. If I hit the retard switch, I can get to cruise altitude around 390. However, 400-410 doesn't concern me for a few minutes. Down low, I can climb very aggressively and never get near 400 and I usually lean to 100-125 ROP after 1000' AGL.

I struggled with timing on the 10. It want's about 32* when LOP at 10K' However, with that timing curve, I would hit 430* at the upper part of the climb while ROP. In my case, I added an knob to adjust timing advance to deal with this (home grown EFI). I can now get to 14K maxing out at 390*. For folks with fixed timing curves, this is a real challenge. You will want 22-25** for your ROP climb at 8000' to deal with heat, yet you will want 30-32* when LOP in cruise at 8000' to provide efficiency/speed. No way to deal with this dilemma with a fixed timing curve. This is an area where the SDS system really shines over the others.

The RVs have a bit less cooling flow than certified and instead depend upon top quality baffling installation to get the heat out.

Larry
 
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I'll echo Larry's comments on the timing on your pMag if you've got one. I set mine at +3 instead of 0 and my high CHTs were improved greatly.

Of course all the advice about making your baffling as perfect as it can be is also extremely relevant.
 
My newly acquired RV 7A equipped with the xio360 (130 hrs on engine) is showing between 420 and 435 degrees CHT on climbout even with full rich mixture and a cruise climb of 120 to 130 KIAS to altitude.

All cylinders or only some of them?
 
All cylinders run above 425 on cruise climb

the cowl flap/louvered vent approach may be a "band aid" but it seems to me far easier than replacing the (new in 2012) baffling. The airplane and engine only has 125 hours on it. Furthermore, it seems to me that adjustable cowl flaps give you some variable adjustments in flight..and if they were polished aluminum, they would look nice
 
All cylinders run above 425 on cruise climb

the cowl flap/louvered vent approach may be a "band aid" but it seems to me far easier than replacing the (new in 2012) baffling. The airplane and engine only has 125 hours on it. Furthermore, it seems to me that adjustable cowl flaps give you some variable adjustments in flight..and if they were polished aluminum, they would look nice
I doubt you will need to replace the baffles, just tune them up a bit. I want to "third" Larry's good advice on checking your timing - something seems off based on your numbers.
 
All cylinders run above 425 on cruise climb

the cowl flap/louvered vent approach may be a "band aid" but it seems to me far easier than replacing the (new in 2012) baffling. The airplane and engine only has 125 hours on it. Furthermore, it seems to me that adjustable cowl flaps give you some variable adjustments in flight..and if they were polished aluminum, they would look nice

There is always an easier way. As mentioned, no need to replace the baffling; Just fix it. Might take a couple of days and you'll learn a lot about your engine. You could always pull the power back 3". That's even easier than a cowl flap. As with most things in life there are usually numerous benefits to "doing it the right way." If you get your baffling sorted out, there is no benefit to variable adjustments in cooling flow, unless you reduce the size of your exit area to reduce cooling drag. Also, this could be mostly from ignition and cowl flaps will do little to help. The reports that I have seen show around a 15* reduction in CHTs with cowl flaps with a 3 knot speed penalty. IMO, that still leaves you hotter than many and you still still can't climb less than 130. It is less about how much air flows through the cowl and more about where the air goes between entry and exit.

Further, if you are seeing 425 CHT in Kentucky spring, Just imagine what it is going to be like in August, when the temps at 8000 are 30 degrees warmer than they are now.

One of the big benefits of proper cooling is not having to throw huge amounts of fuel at your engine just to cool it down.

No judgement, just an opinion.

Larry
 
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Some additional thoughts...

I would start with checking the accuracy of the CHT sensors by putting them in boiling water and see what the indication is.

I would check baffling fit and improve if necessary.

Then i would put a “spoiler” on the cowling outlet (see picture) to enhance suction out of the lower cowl.
I had the same issues.
This will cost you a couple of knots airspeed but will show whether you get the temps lower with cowl flaps (as they do just the same.
The lip, or “spoiler”, is to be considered a temporary fix.

If you want to lower your temps further, change ignition timing.

Once you are happy with everything, order cowl flaps and have a winter project with installing them.

Success!!!
 

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The Titan may have higher compression as a factor also.

And, just to jump on the band wagon-----check timing.
 
Sage advice from all...and I really appreciate it. I will check the timing first and then move on to the baffling..Thanks to all for weighing in..
 
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