New Titan 340 Engine Break in - High CHT's

[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/uploads/2017/08/Manual-LC114v28.pdf

 

[skywagon8a]

View attachment 65849

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.

 

[akavidflyer]

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.

If you measure the steps in the pins, its pretty easy to have any machine shop make them. I turned down some of the higher pitch pins to make a 35.5 and 36.5 pin for mine. If you have an adjustable prop, its worth the extra time to get the pins made to really dial it in, to your plane and your needs.

 

[Colorado-Cub]

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.

Just one detail to add here that may be useful for some (and not for others):

By using the EICAD software, you can adjust curve from a known baseline. A vs B is a good starting point, but rather than set up a beeper box of old with a degree wheel on the prop flange (or do the math to determine thousandths BDTC on #1 via a piston dome), those of us with PMAGs can simply hook up, bump the entire curve up or down, then test. I don't disagree with overall sentiment above, but being able to move your entire curve of your choosing (A or B) up or down in a range while being able to set extents of adv or ignition cutoff without breaking out a degree wheel is handy. I suspect those of us that live in hot high air 99% of the time chase CHTs via timing more than most so this little feature might not be as useful for everyone else.

Someday PMags will enter 1980s era of technology and allow us to adjust the actual curve (ignition via TPS+RPM), but until then this is good enough for a our beloved air cooled monsters.

 

[stewartb]

Good comments. My Pmag education has focused on a high compression angle valve engine operating near sea level with a CS prop. I have no experience with high and hot operations. To the curve? The Pmag guru himself told me to ditch my A-B switch and run in A curve. My take on the conversation was that I needed to guard against detonation and wouldn’t see any useful gain for pushing the timing beyond 34°. As timed now I’m closer to 31° of advance. It doesn’t lack for power or responsiveness.