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New Titan 340 Engine Break in - High CHT's

CharlesTym

Registered User
Hi Folks after some feedback on your enginebreak in experience. I have a new cub with the Titan 340 FI/Low compressionengine and approx 10 hours on the clock.
Its not using much oil at all - 0.15 qts over thelast 3 hours. The 340 engine / prop (3 blade Catt0 74x50) combo is super smooth.
The new Mobile built Continental Titan 340s are abig improvement on the older ones - like the one in my old 2013 CC SS.

The rear cylinder head temp are regularly hittingthe high 390's (and above) even around 2250 to 2350 RPM - there are some gapsin the baffling and this is a priority to get fixed.
Can post before and after photos once the bafflinggets replaced.

On the last flight - which was an 80 deg F day - Icouldn't climb out from 500 AGL with out the rear CHT's quickly going above 400def F.
On a 50 deg F morning the rear CHT's are muchbetter / manageable (375 to 385 range) for a new tight engine.

Break in has followed as closely as possible toSB0003 from Continental - first hour at mostly 75% power and subsequent hoursat 65% to 75%.
The oil stills looks super clean (will change itin 1 hours time and cut the filter)

Appreciate any experiences you have had withbreak-ins - especially the Titan 340 and Lycoming 320/360 types.
Main concern is that the baffling is driving thesehigh CHT's in the warmer ambient temps.
I know its early days with this engine but itshard to get a feel for what normal should look like.

Thanks in advance

Charles
Mudgee
Australia

 
Baffling is key. Airframe, baffle set up, ignition system, what timing? All we know is that you have a 340 engine. Have worked on a lot of them on Carbon Cubs and have figured out some of those nuances. Privy to the fixes Legend made when they started using them.
 
What cowl? Where’s the oil cooler? Lots of possible culprits.

How much cooler are the front cylinders running?
 
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I’m really curious about this. A fuel injected factory built 340 is different than a CC engine. Baffles vs plenum is also different. I hope we hear about adjustments and results.
 
I have 150+ hours on my Titan 0-340, and had those same problems.

First fix the baffling of coarse, and any other air getting in the cowling from the front (spinner, air filter, cowling etc.).

The thing that made the biggest difference with mine was putting a ramp infront of the front cylinders to direct some of the air over the top to the back cylinders. My ramp is 1" and angled at 45* - but I have plenums, so yours may need to be different.

The other is to put more exit holes/ fins for air to get out of the cowling, it doesnt matter how much air goes in, if it can't get out fast enough.

I also backed off the timing just a hair.
 
Bear in mind that a lean mixture will also create higher cylinder temps. Make sure you have the MA 4-5 carb. Some of these engines were delivered with the smaller carb and weren’t getting enough fuel. They all ran hot. I went to fuel injection and eliminated the problem. Cooling air flow will not compensate for a lean mixture. The position of the butterfly will decide which cylinders will be getting the leaner mixture and will change with throttle position.
 
The OP indicated that his engine has FI. And baffles, so not a Carbon Cub plenum. That's what makes it interesting.
 
To the ramp comment? Here’s what works on my engine. My temps are very even after adding it and increasing the coverage with aluminum tape. Balancing temps is a process.
 

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To the ramp comment? Here’s what works on my engine. My temps are very even after adding it and increasing the coverage with aluminum tape. Balancing temps is a process.

Interesting, did you try the ramps all the way across? That’s about the same height as I did but the whole width


Sent from my iPhone using Tapatalk
 
BB Still running full rich as part of the engine breakin. 10 hours so far and probably start leaning after 20 hours TT
 
This cub has baffles. If the baffle enhancements don’t lower the CHTs enough we will looking at fabricating a plenum. Expect this whole process to take some time but will keep everybody posted.
 
15 to 20 degrees on average - not massive. The Garmin EMS is saying that there is 10 to 15 deg difference between 1 (lower) and 2 cylinder CHTs which is a little surprising.
 
I will assume you have a standard cub cowling with Cheeks on the doors. Simple and quick fix is get the baffling tight. Remove the cowl doors and put the hinge in the full open position now use aluminized tape on the hinge, this will seal that air leak through the hinge. If your front cylinders are running in the lower 300 range start with adding 2 inches of the same aluminized tape above the front baffle on the cylinder heads of 1 and 2. This should force more air over the top to cool the rear cylinders. Adjust with more or less tape until front and rear cylinders CHT'S are close. After a year or so when you have see all the temp operation ranges you can build ramps (make them a bit lower then the tape) Check you fuel burn and make sure you are not running lean for your RPM. The new electronic mags with timing advance are notorious for causing high CHT'S if possible check and adjust timing profile.
DENNY
 
The Garmin EMS is saying that there is 10 to 15 deg difference between 1 (lower) and 2 cylinder CHTs which is a little surprising.
Nothing wrong with this. Your only concern is not to allow the maximum CHT to remain above 400F. A little bit over can be cured by enrichening the mixture a bit.

Did you close those gaps in the baffles? If not, the air passing though those gaps contributes nothing to cooling the cylinders. That could be just enough to keep the CHTs in check.
 
15 to 20 degrees on average - not massive. The Garmin EMS is saying that there is 10 to 15 deg difference between 1 (lower) and 2 cylinder CHTs which is a little surprising.

This is normal for most carb lycomings. Depending on plane and phase of flight #2 can also have the highest CHT's Use the tape to adjust temps between cylinders 1 and 3, 2 and 4.
DENNY
 
The original cub cowling was made for much lower HP engines. Over the years the HP has doubled with little or no change in cowling. It is a very common problem that seems to most always require some type of work. That may be why some builders are quick to say you don't need CHT/EGT instruments ( it would require more work to do it right!!)
DENNY
 
1. Front ramps...20F, if you drill 12 1/4 inch holes in them, you will not raise front temps and still drop rear temps.
2. box around front of engine.....27F
3. Lip on lower cowl exit...10F
Measure pressure on hot side of cowl at 100 mph indicated, should be zero(compared to ambient) cold side will be 4.2 inches at 100mph..(2450 rpm).Lycoming specs their engines to have 4 inches of water air pressure across them for proper cooling.
There’s 57 degrees for ya...
 
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