Titan 340 engine problem and solutions.

[seastar]

As I have posted on here and on the General CubCrafters forum, I have had had failures of the Titan engine.
I had to replace all of the cylinders at 250 hours for several problems.
The new cylinders have about 30 hours and have been very uneven in temperatures with some cylinders egt running 200 DF hotter than others and some cylinder head temps running over 400 at 2100 rpm and full rich while others run 75/80 DF cooler. It's been driving me crazy. The airplane was almost unflyable after the new cylinders were installed.

After I posted some comments about this on the General forum Jon from CubCrafters customer service contacted me with two suggestions to try and cure these problems.
First, he suggested I install the carburetor mod that evens the fuel flow to each cylinder.
Second, he said that the factory has been reducing the max timing from 25 degrees Before TDC to 22 degrees.
My old airplane, #124 has an adjustable timing wheel unlike newer engines so removal of the prop and replacement of the timing gear was not necessary.
While we were at it we drilled new holes in the cowl flaps and opened them about another 1/2 inch.
The results of these modifications have been spectacular.
Yesterday at 3500 feet MSL, 2200 RPM and leaned to about 1250 egt on the hottest cylinder with 6.7 gallons fuel flow the hottest cylinder head temp was 389 and the coldest was 372.
The hottest egt was 1242 and the coldest was 1220.
I have never seen temps that low or that balanced on this airplane and I am sure I could have leaned it more and run LOP.
I have been flying the airplane full rich at most times to keep the cylinder head temps under 400.
I know that Titan says that 450 is the max but after losing my first set of cylinders that were never run over 400 I am very caucious
In any case I am very pleased with the results of these simple mods and I can't tell any difference in the power at takeoff at full throttle.
I expected that the timing reduction would make a difference but it has not that I can tell.

Thank you Jon for your excellent suggestions!

If you have been having problems like these and don't have the carb mod or the timing mod you might want to do them.
Bill

[Jon Delamarter]

Bill,

That is fantastic news! Your results are even better than I expected. Doesn't even sound like the same engine!

Just a couple of details for other folks considering these mods:

• Reduced Ignition timing - As Bill mentioned, early Carbon Cubs had an adjustable magnet setup. These can be adjusted, as Bill did. Later aircraft have fixed magnets and will require swapping out the timing ring with a different ring, part number LSEMRA-4-22. Reducing the nominal timing from 25 to 22 degrees before top dead center typically results in reduced CHTs and a minuscule power reduction. I say minuscule because I've only had one person ever tell me they could tell a difference, and he was a STOL competitor, measuring his takeoff performance in inches. For most folks, it may effectively increase power, as it typically allows the pilot to operate the engine at higher RPM for a longer period of time.
• Carb Mod vs Intake Mod - I wanted to clarify that while Marvel-Schebler does offer a perforated fuel nozzle upgrade for older carbs, the mod Bill referenced was actually a modification to the sump/intake system where it meets up with the carb. This is Service Instruction 31; the sb doc is HERE, the kit is available HERE. This mod only applies to Carbon Cubs 293 and earlier. Most owners have reported markedly improved temperature spreads, allowing more effective leaning and therefore reduced fuel burn and smoother running.

---

Here's a pic of an older style, adjustable timing ring.

Old Style Ignition Timing Ring.jpg

---

Here's a pic of the new style fixed timing ring.

New Style Timing Ring.jpg


Hope this helps,

[seastar]

Here is a screen shot of the D-180 when I test flew the airplane.
image.jpg
I have a question.
The screen was changed after the aircraft had the mods preformed. The mechanics swear they did not change the display.
The change is the display in the upper right hand corner that says 44% ROP.
I have no idea what that means. That spot is where the OAT was before.
Anyone know what ROP means?
Bill

[txcub]

ROP = Rich of Peak.

Jon

Here is a screen shot of the D-180 when I test flew the airplane.
image.jpg
I have a question.
The screen was changed after the aircraft had the mods preformed. The mechanics swear they did not change the display.
The change is the display in the upper right hand corner that says 44% ROP.
I have no idea what that means. That spot is where the OAT was before.
Anyone know what ROP means?
Bill

[seastar]

OK, so if it's rich of peak I wonder how that is calculated?
I did notice that it reads 0% at idle. Does that make sense?
I will need to think awhile about that and if it's a useful display.
I have always used EGT as a peak indication and leaned to 50d either rich or lean of peak depending on the engine and what type of fuel system was on it as well as the power setting.

I wonder where my OAT display went and how to get it back.
The Dynon manual makes no mention of ROP display.
Its not listed in the manual in parameters that can be displayed.
Bill

[Treetopflyer]

Bill,
I have the same D-180 in my RV-4. The 44% that you're seeing is the percentage of power your engine is making and the ROP is Rich Of Peak. What you'll notice is that as your MAP increases so will that percentage that you're seeing. In my RV-4, I use the MAP and the percentage of engine power to let me know when it's safe to lean the engine. Basically, anything under 65% powers and you can lean the heck out of the engine and not worry about doing any damage from possible detonation. When you're leaning the engine you'll notice that ROP change to "Peak" and then to LOP (Lean of Peak). As far as the OAT, mine shows up on the middle left of the screen by the airspeed indicator ribbon in the area where yours is showing MAP and RPM's. Mine also shows alternator voltage.


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[seastar]

Thanks TreeTop
That make a lot more sense.
Now I need to find out how to recover OAT. Don't need two RPMs and MAPs.
I have spent about an hour reading the manual to no avail.
Seems as though I spend more and more time studying technology rather than using it.
Damned stuff is great when it works and stupid frustrating when it doesn't.
Must be my age!
Bill

[seastar]

Yeah, I know, it's working. Someone, probably me has just pushed a wrong button.
Hummm! Maybe RPM and MAP next to the airspeed on other screens is not so bad.
I guess I could stick a wet finger out the window to tell the OAT.
Bill

[Treetopflyer]

Bill,
If I have time today, I'll go out to my hangar and boot up my D-180 and go through the configuration screens and see if I can get some answers for you. I also noticed on yours that I don't see a "true airspeed" reading. I see your indicated airspeed, but not your "true". Have you ever shown that? You definitely need your OAT probe to be working properly to to get a "true" airspeed reading because "true" airspeed is a "calculated" airspeed and OAT is one of the parameters that's used in that calculation.




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[Pete D]

Thanks TreeTop
That make a lot more sense.
Now I need to find out how to recover OAT. Don't need two RPMs and MAPs.
I have spent about an hour reading the manual to no avail.
Seems as though I spend more and more time studying technology rather than using it.
Damned stuff is great when it works and stupid frustrating when it doesn't.
Must be my age!
Bill

To get OAT/Density ALT/True Airspeed displayed over by the airspeed tape you need to set up "info". There is a left and right info. Options can be found by:

With D180 fully powered up and no menus open at the bottom:

Press button 2 (second from left end)
Select "more" (button 5)
Select "info" (button 2)
Select "left" (button 1)
Select "OAT" (button 4)

There are other options available for both left and right info, you can select the ones you prefer.

I believe the CarbonCub default is with "OAT" on the left info and "VMeter" (volts) on the right info so you can always keep an eye on your main buss voltage. If you select VMeter there is M (main) I (internal back up battery for the D180) and B (an unused input for backup buss)