New Titan 340 Engine Break in - High CHT's

[bcone1381]

....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-effect...nd-efficiency/

[CharlesTym]

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

[stewartb]

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.

[fobjob]

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....

[CharlesTym]

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.

[stewartb]

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.

[DENNY]

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

[CamTom12]

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.

[stewartb]

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.

[CamTom12]

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.

[Colorado-Cub]

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.

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!

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

[CamTom12]

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!

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!

Not knocking the pmags, I love that there’s a self-powered product out there using newer tech than a traditional magneto.

[stewartb]

Eicad is discussed in the Pmag manual. So are increased CHTs and what to do to correct them. I hope Charles Tym reads the manual and gets some relief from his high temps.

https://emagair.com/wp-content/uploa...l-LC114v28.pdf

You can add an EICommander on the panel if you want true dynamic programming capability. https://eicommander.com/

[pittsdriver]

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?

[JohnnyR]

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.

[stewartb]

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?

[skywagon8a]

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.

[stewartb]

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.

[JohnnyR]

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/s...d.php?t=167948

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?

[skywagon8a]

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/s...d.php?t=167948

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.

[JohnnyR]

Run-in done for two hours @ Aero Sport Power. I have the data for that and CHT’s were better, but you know how that goes with clubs, cooling fans, etc. Not comparable. Break-in is being done on the airplane.

Correct - pitch set on the Sensenich ground adjustable for cruise. Even with that setting (pitch 6 on pin gauge) it will spool up at full throttle to 2,800 rpm after a short while in cruise flight.

Will do. Interestingly, my quick readings on the Van’s forum show that most parallel valve Lycomings do best on the A curve or a custom B curve @ -1.4 advance shift and 34 degree max advance.

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.

[stewartb]

What did you set your timing to? The A curve may help but I’d also retard the timing to 5° after TC to see if it cools things down. Do one change at a time so you know what’s what.

What MP are you getting at takeoff? What’s your static RPM?

[skywagon8a]

Correct - pitch set on the Sensenich ground adjustable for cruise. Even with that setting (pitch 6 on pin gauge) it will spool up at full throttle to 2,800 rpm after a short while in cruise flight.

That pitch is not cruise. If it were, the rpm would never exceed 2700. It may be set at a pitch a bit higher than climb with that low manifold pressure and that high of rpm.

[JohnnyR]

I believe that’s recommended for angle valve engines like your 390.

Aero Sport set the timing before run-in @ 25.2 BTDC.

What did you set your timing to? The A curve may help but I’d also retard the timing to 5° after TC to see if it cools things down. Do one change at a time so you know what’s what.

What MP are you getting at takeoff?

[JohnnyR]

There’s only one more pitch setting available for the included pitch pin gauge. I have to get Sensenich to send me their special 8-9 pitch pin.

That pitch is not cruise. If it were, the rpm would never exceed 2700. It may be set at a pitch a bit higher than climb with that low manifold pressure and that high of rpm.

[stewartb]

I believe that’s recommended for angle valve engines like your 390.

Aero Sport set the timing before run-in @ 25.2 BTDC.

God, I hope not with Pmags! We time Pmags at between TDC and 6° after. The ignition’s advance is clocked to that starting point. 25° BTC engines can use TDC on the ring gear. 20° engines need to compensate 5° for the base setting. Adding up to 6° ADC from base is a totally different thing.

As I understand it, Pmags advance is based on MP and RPM. You’re getting a lot of advance at 2460 RPM even with low MP. Try reducing RPM to 2300 and see if temps drop.

[stewartb]

See pages 13-14 for timing instructions. https://emagair.com/wp-content/uploa...l-LC114v28.pdf

[skywagon8a]

Take a look at a power chart for your engine. That appears to be in the 50% range.

[JohnnyR]

Oops - I mistyped! They did NOT time according to conventional mags. It’s timed off TDC or minutely after. I will confirm everything firsthand next week. Back home for a few days to deal with farm chores.

God, I hope not with Pmags! We time Pmags at between TDC and 6° after. The ignition’s advance is clocked to that starting point. 25° BTC engines can use TDC on the ring gear. 20° engines need to compensate 5° for the base setting. Adding up to 6° ADC from base is a totally different thing.

As I understand it, Pmags advance is based on MP and RPM. You’re getting a lot of advance at 2460 RPM even with low MP. Try reducing RPM to 2300 and see if temps drop.

[stewartb]

If you haven’t timed Pmags before? You’ll like how easy it is. Reaching the wiring plug to add the jumper? Not so much. In any case if you’re still running hotter than you want with the A curve at TDC, you can retard it up to 6° more to see if that helps. I’ve never needed an EICAD to fiddle with timing. Between A and B curves and retarding up to 6°, I have enough adjustment potential.