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New Titan 340 Engine Break in - High CHT's

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).
 
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
 

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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.

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
 
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.
 
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.
 
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.
 
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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


Sent from my iPhone using Tapatalk
 
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.
 
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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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.
 

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....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.

Your theory is correct. I'm not a big fan of a preset timing curve.

Below is a link of a Kitplanes Article on the benefits of Variable Ignition Advance. The second to the last paragraph is good place to skip to see a scientific conclusion of its benign benefits.

https://www.kitplanes.com/the-effec...linder-head-temperature-speed-and-efficiency/
 
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.

stewartb Yes the EGTs are very close (1305, 1305 1290, 1285). Fuel Flow is 13 USG/Hr at take off/full power and at 2300 RPM is 8.4 USG (full rich).
I havent started leaning the engine yet. Will verify the timing this week and advise.

Much appreciated
 
Your fuel flow at 2700 RPM should be 15.5 gph according to the Lycoming 340 manual. Your 2300 RPM flow is right where it should be. From my own experience if full power fuel flow is low the engine will get hot and stay hot for longer than I would have thought. First order of business, make sure your throttle and mixture cables are adjusted properly.
 
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M
I built a box around the flywheel. Didn’t change a damn thing


Sent from my iPhone using Tapatalk

Thats a lot of work for no result. Did you measure anything else besides CHT before the build? At this point I would say measure the hot side pressure compared to ambient. Should be zero. The big effect of the box is to lower hot side pressure, not just CHT changes....
 
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.

stewartb hi

You raise great points. Spoke with Brad from EMagair (who provides legendary customer service) about the settings.
As I guess you well know - the new EMag units get shipped standard with the more aggressive B curve ignition timing activated.

By putting the jumper between jumpers #2 and #3 you enable the less aggressive A curve ignition timing curve you reference above.
So will go step and step and see what improvement we get from making all the changes to ignition settings and baffling.

My EGT's are relatively low (high 1200's to low 1300's) compared to 1400+ on my Carbon Cub with the same Titan 340 (but not FI'ed) which ties intot he comments EMag make about higher CHT's and lower EGT's.
 
Yes, Pmags require the addition of a 2-3 jumper for the A curve, but it may have been added by the engine builder. That’s an easy thing to check.

I’m curious about the full throttle fuel flow. Did Continental provide a run sheet? What was their full throttle fuel flow on the test stand? Do you have a fuel pressure gauge? What pressure are you getting? Are you using the high pressure pump for takeoff? In addition to Lycoming specs for 15.5 gph in a 340, Cubcrafters says 16.2 gph. Fuel flow may explain your temps, assuming your instrument is correct. New plane problems. ;)
 
His"take off full power" is most likely not 2700 RPM where you would see the most fuel flow, I suspect that would be why it does sound low. A better question is what is the fuel flow and RPM at MAX rpm, level flight, close to the ground. Fuel flow should be calibrated to airflow and that is dependent on RPM. I could be wrong but I pretty sure that is how that system works. It is something to look at but I think it is a simple RPM issue
DENNY
 
I run dual pmags. I got a copy of their software and modified the “B curve,” or the jumper-out curve.

There was a fair amount of RV folks that had CHT issues with various EIs and there’s a huge thread on one of their forums dedicated to that, but the takeaway is to set the B curve advance shift at -1.4° (base timing will be 25.2°) and max advance to 33.6°.

The numbers look weird because of a bits vs degrees thing, I think. RV folks noted this was a more gentle timing curve as far as CHTs went.

I haven’t flown mine with the change yet. But I was having CHT issues with the jumper in, or the “A curve.” I even had the PMAGs retarded from TDC 3 or 4° as well.

You can make the change with a laptop and some free software, though you’ll have to rig up a quick RS232 harness and get a USB adapter. Or they sell an EICommander box thing that will also let you adjust the B curve.
 
Shifting the curve to retard from 1-6° is easily accomplished by setting timing 1-6° after TC. The benefit of the B curve is for LOP with tuned fuel injection. Guys running carbs ROP low and slow won’t benefit much from EI. The same is true for FI when running ROP low and slow. I do enjoy how well it starts a hot FI engine, though. And automotive spark plugs, which some believe is the biggest advantage of EI.
 
Shifting the curve to retard from 1-6° is easily accomplished by setting timing 1-6° after TC. The benefit of the B curve is for LOP with tuned fuel injection. Guys running carbs ROP low and slow won’t benefit much from EI. The same is true for FI when running ROP low and slow. I do enjoy how well it starts a hot FI engine, though. And automotive spark plugs, which some believe is the biggest advantage of EI.

Kind of broad, sweeping statements there…

I definitely saw smoother operation, better starts, and increased fuel efficiency with EI and my carbed “low and slow” O-320 during ROP ops.

There’s been more than one lycoming O-series engine that’s noticed decreased temps with no apparent loss in performance/efficiency by running a modified “B curve” over a clocked “A curve,” though in theory they should be the same thing. Seems like the adjusted B curve is gentler.

I should have first flight on my modified B curve this weekend, so I’ll have some data for myself as well. Took a $20 adapter cord and about 15 minutes to modify my B curve using the free em again software.

9aa91d1b2b07fa38dfe3c7a42673cdd9.jpg
 
Kind of broad, sweeping statements there…

I definitely saw smoother operation, better starts, and increased fuel efficiency with EI and my carbed “low and slow” O-320 during ROP ops.

There’s been more than one lycoming O-series engine that’s noticed decreased temps with no apparent loss in performance/efficiency by running a modified “B curve” over a clocked “A curve,” though in theory they should be the same thing. Seems like the adjusted B curve is gentler.

I should have first flight on my modified B curve this weekend, so I’ll have some data for myself as well. Took a $20 adapter cord and about 15 minutes to modify my B curve using the free em again software.

9aa91d1b2b07fa38dfe3c7a42673cdd9.jpg


After easily modifying 3D fuel+ignition curves based on RPM/TPS/etc for the last 30 years for motorsports applications, it is almost comical I am excited to see the beginnings of that capability for E-Mags! :D

I had no idea this software existed, so I greatly appreciate you posting this picture.
 
After easily modifying 3D fuel+ignition curves based on RPM/TPS/etc for the last 30 years for motorsports applications, it is almost comical I am excited to see the beginnings of that capability for E-Mags! :D

I had no idea this software existed, so I greatly appreciate you posting this picture.

No worries!

I haven’t done it for 30 years, but I’ve done a fair amount of EFI tuning as well. Prepare to be underwhelmed with your potential adjustments on the pmags. Those boxes are it! :D

Not knocking the pmags, I love that there’s a self-powered product out there using newer tech than a traditional magneto.
 
So your cht's are in the 380-390 range in cruise and the rear go over 400 in climb and you have 20 hrs on the engine. Looks pretty normal to me. If the cht's are less than 450 in climb there is no problem. I don't know what you guys think are normal cht's but when talking to a tech at Lycoming a few years ago he says around 375 is ideal. Redline is 500 ao you are well below. If you have steel cylinders it could take up to 50 hours to completely break in. Fly it awhile more and see what you get in another 20 hrs. I have built 5 Super Cubs and 10 experimental airplanes so have a lot of experience in breaking in engines. Also when you did the initial 5-10 hrs did you run it 26-2700 rpm and full rich?
 
I’m curious if your modified B settings did the trick.

Kind of broad, sweeping statements there…

I definitely saw smoother operation, better starts, and increased fuel efficiency with EI and my carbed “low and slow” O-320 during ROP ops.

There’s been more than one lycoming O-series engine that’s noticed decreased temps with no apparent loss in performance/efficiency by running a modified “B curve” over a clocked “A curve,” though in theory they should be the same thing. Seems like the adjusted B curve is gentler.

I should have first flight on my modified B curve this weekend, so I’ll have some data for myself as well. Took a $20 adapter cord and about 15 minutes to modify my B curve using the free em again software.

9aa91d1b2b07fa38dfe3c7a42673cdd9.jpg
 
I'm curious, too. I don't characterize the B curve as gentler unless a guy custom programs it. My understanding is it's just a more advanced timing curve. Emag's head guy (sorry I don't remember his name) advised me to disable the B curve and forget about it for my engine. Maybe there's value in it for lower compression. That's not my area of interest. If in doubt, call Emag and ask the guys who make them.

Johnny, are you seeing higher than expected CHTs?
 
Based upon a discussion in another thread where it was mentioned about setting the timing at 4 degrees after TDC, I did it. When I initially installed mine there wasn't any reference for this procedure. Now I notice in the current manual that when timed at TDC a 4 degree ATDC is built in for starting. So......that places mine at 8 degrees ATDC for starting. Then I removed the jumper which gave me an additional 1 degree of advance. The other day I did my first fuel injected hot start with this timing. It started very smoothly on the first cylinder, just like an automobile. The best hot start I've ever seen with an injected Lycoming. Normal running was unchanged with no change in temperatures.
 
A curve uses 34* advance. B curve uses 39*. A curve requires the jumper wire. No jumper and you're in B curve.

The manual suggests anywhere between TC and 6* after for normal installations. I've used 6*, 4* and 0* and don't recognize any difference, so I settled on 2-3* after for a safety margin. My engine spec is retarded 5* from most Lycomings. If you run an angle valve engine pay attention to that and adjust accordingly. Since Pmags time at TDC and the standard Lycoming uses 25* and my engine uses 20* timing, I have to use 5* after as my TDC reference (2 teeth on a 144 tooth ring gear.) Forget to do it one time and it may destroy a ring gear and/or a starter. ;)
 
Yes. We’ve carefully gone through the baffling. I’m thinking I should have installed the jumper for the A curve for my break-in and Phase 1 flying. Engine stats in cruise flight @ 4,500’ and 59F OAT can be seen below. Lots of fuel to keep it happy at those settings.
Engine now has 30 hrs and is not much better in CHT temps (although is otherwise running well. Aero Sport has been great to work with). I will install the jumpers to move from “hotter” B curve to A curve. Perhaps will do the custom settings the Van’s guys and e-Mag rep recommend, but we’ll see how the A curve works. https://vansairforce.net/community/showthread.php?t=167948


IMG_3882.jpg

I'm curious, too. I don't characterize the B curve as gentler unless a guy custom programs it. My understanding is it's just a more advanced timing curve. Emag's head guy (sorry I don't remember his name) advised me to disable the B curve and forget about it for my engine. Maybe there's value in it for lower compression. That's not my area of interest. If in doubt, call Emag and ask the guys who make them.

Johnny, are you seeing higher than expected CHTs?
 

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Yes. We’ve carefully gone through the baffling. I’m thinking I should have installed the jumper for the A curve for my break-in and Phase 1 flying. Engine stats in cruise flight @ 4,500’ and 59F OAT can be seen below. Lots of fuel to keep it happy at those settings.
Engine now has 30 hrs and is not much better in CHT temps (although is otherwise running well. Aero Sport has been great to work with). I will install the jumpers to move from “hotter” B curve to A curve. Perhaps will do the custom settings the Van’s guys and e-Mag rep recommend, but we’ll see how the A curve works. https://vansairforce.net/community/showthread.php?t=167948


View attachment 65849

Was the engine broken in on a test stand? It's clear you have a low pitch on your prop given the parameters shown. That engine is loafing. At those power settings, my IO-360 with the P-mag jumper installed will use a maximum of 8 gph with the CHTs a bit lower than yours. Install the jumper to try getting the CHTs lower.
 
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