New Titan 340 Engine Break in - High CHT's

[CharlesTym]

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

[skywagon8a]

The rear cylinder head temp are regularly hitting the high 390's (and above) even around 2250 to 2350 RPM - there are some gaps in the baffling and this is a priority to get fixed.

Fix this first......now.

[Steve Pierce]

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.

[brown bear]

How much EGT rise do you get when leaning ?

[stewartb]

What cowl? Where’s the oil cooler? Lots of possible culprits.

How much cooler are the front cylinders running?

[stewartb]

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.

[bda]

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.

[Bucket List]

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.

[stewartb]

The OP indicated that his engine has FI. And baffles, so not a Carbon Cub plenum. That's what makes it interesting.

[DENNY]

What plane is this in PA18, Carbon cub, or other? DENNY

[stewartb]

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.

[RaisedByWolves]

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


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[stewartb]

No reason. Objective achieved.

[CharlesTym]

BB Still running full rich as part of the engine breakin. 10 hours so far and probably start leaning after 20 hours TT

[CharlesTym]

PA 18 type Legend

[CharlesTym]

Job number 1 !!! Happening in a few days time.

[CharlesTym]

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.

[CharlesTym]

Yes will post lots of detail but it will take a few weeks due to work and family commitments.

[CharlesTym]

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.

[DENNY]

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

[skywagon8a]

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.

[Steve Pierce]

Legend started using the MA4-5 carb so I assume this is the case here.
?

[DENNY]

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

[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

[RaisedByWolves]

What sort of ignition? Varied timing?


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[fobjob]

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...

[CharlesTym]

Its the standard timing as from Continental - will have to confirm with them the exact timing.

[CharlesTym]

Quite right

[CharlesTym]

New Continental Titan 340 with E Mags x 2

[CharlesTym]

[QUOTE=Steve Pierce;821618]Legend started using the MA4-5 carb so I assume this is the case here.
?[/QUOTE

It has a Fuel Injection unit from Air Flow Performance - sorry should have been using quotes before

Thank you for your input/advice

[CharlesTym]

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...

Thank you very much - with keep you posted. Just posting a whole bunch of before (baffling redone) photos tonight (Oz time).

[CharlesTym]

Photos of existing baffling on my Legend Cub - prior to the baffles being rebuilt.
Areas of concern circled in green on the relevant photos.
The photos are not labelled by most should be easily identifiable.

Reload PDF - now testing

[CharlesTym]

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.

Yes -very similar to my old Carbon Cub which has very low CHT's. This design/feature seems to be a common denominator in engines with lower CHT's

[CharlesTym]

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

DENNY hi Just posted photos of all the baffling, cowls etc. Thank you for your advice, we will work methodically through this list of enhancements and post the results in a few weeks.

[CharlesTym]

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.

BucketList -This is a new Fuel Injected Titan 340 - I should have made it clearer in my initial post. The issues you describe are exactly the type of issues I had in my CC SS with a Titan 340 and MS Carb. Did the SB for the perforated nozzle which helped a fair bit but not perfect.

[stewartb]

Your baffles aren’t bad. Some RTV will seal those little holes but I wouldn’t expect much difference. I’d check two things on the Pmags. Verify where they’re timed. Most guys target TDC, which is fine for most engines. You can retard them up to 6° and in your case that may be what you need. The other thing, make sure they’re set on the A curve, at least as you chase your temps.

To the FI side of things, are your EGTs fairly consistent across all cylinders? What’s your fuel flow at full rich? Electronic ignition masks the normal “lean stumble” so flow and EGTs are your best tool for assuring your FI is doing what its supposed to at all four injectors.

[RaisedByWolves]

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...

I built a box around the flywheel. Didn’t change a damn thing


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[bda]

On my 0-340 with P-mags, The high temps were only happening when the Pmags were "advanced" because of manifold presure. I found that prop pitch and how it increases the manifold presure played a big part in my high temps.
If I reduce pitch and lower MP, the timing advance on the Pmags doesnt seem to hit in the cruise rpm.
I still had to increase cooling so that I could run at higher MP, but I could get into cruise without running over 400*
With Pmags you absolutely have to have a MP gauge, and pay attention to it.

[RaisedByWolves]

Some cubs with the surefly mags on varied timing are running hot. I have a theory, sense they change depending on MP and we know the borer and climb props don’t make much MP, I think the mag is changing the timing thinking the engine isn’t working hard, low MP when it is really at full climb power. When I get back to my cub I’m going to turn off the varied timing and see. I was running hot on climb on floats. Someone was telling me they turn off the varied timing on the pmag when they fly out west because it runs too hot


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[stewartb]

Turn off how? Disconnect the MAP line? With Pmags you’d be better off retarding timing 5-6°. Chances are you wouldn’t notice and performance change. If you did? Run it in B curve when you need that extra 5° of advance.

The OP indicated his timing was wherever Continental set it. Timing the Pmags and setting the timing curve would have been high on my pre-start inspection list.