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Engine/RV-10 stuff I learned at Airventure 2021

Thanks for posting this info! Good summary of a variety of past EAA webinars/AirVenture presentations.
 
Some of those recommendations make no sense. Perhaps incomplete notes? For example, "When flying 13,000+ msl it is okay to lean to the peak EGT." Who said that, and what is their reasoning?
 
Some of those recommendations make no sense. Perhaps incomplete notes? For example, "When flying 13,000+ msl it is okay to lean to the peak EGT." Who said that, and what is their reasoning?

Mike Busch, he was explaining that if you wanted to go at a faster speed than lean of peak operations, you can run at peak EGT (pending CHT temps) and there is no risk of harm to your engine.
 
Was there a recommended place to start with taping the #3 & #4 cylinders to bring the temps up?

I didn't ask that follow up question. I plan to cover a small portion of the top of the fins on both 3 and 4 wrapping an inch down the sides. And I'll keep blocking off until the CHTs are within 10-15 degrees of each other.
 
Some of those recommendations make no sense. Perhaps incomplete notes? For example, "When flying 13,000+ msl it is okay to lean to the peak EGT." Who said that, and what is their reasoning?

I believe his reasoning is that at 13,000+, the “red box” doesn’t exist because the power is below 60 percent, so it doesn’t matter where you run it.. peak, lean, rich.. whatever.
 
I believe his reasoning is that at 13,000+, the “red box” doesn’t exist because the power is below 60 percent, so it doesn’t matter where you run it.. peak, lean, rich.. whatever.

John Deakin’s articles mentioned something similar - I think he used 9000’ PA as the point for NA engines that if you wanted to lean for best power (approximately 80* ROP) you can’t hurt anything since the engine isn’t making enough power at those altitudes to do so.
 
I try to not look too closely at exact power settings and EGT numbers. I think his main points are to keep CHTs below your set value as that is the best proxy we have for ICP. Personally I generally cruise about 21" MAP, 2450 RPM and usually just lean of peak in order to keep my CHTs up around 350. If I go too lean at those power setting my CHTs drop way off.

As far as burning valves. I believe there is virtually nothing we can do to cause it. If you get a bumb valve it is inherent in a poorly seated valve off the assembly line. Take some more money Mr. cylinder manufacturer...
 
Ok, I've been watching, but you guys just stepped into my office.
We fly this little O320 with a tractor carburetor that we've worn out multiple times due to "excessive" throttle movements :). (FFI Formation) It is attached to an amazing RV-9A wing that amazes us every time we traverse a thousand miles with ease.

Cut to the chase. Setting engine power / mixture at 14.5k' is comically trivial. It either runs or it doesn't! We fly this profile sucking O2 often (I'm addicted to the stuff). The tiniest power or mixture change at that altitude is a real stumble either side of "peak".

Tanya flies at "a little stumble, then a little rich." It works.
I spend hours monkeying with RPM, mixture, throttle butterfly position, carb heat position... Passing the time.

It is just a question of how you choose to pass your time sometimes.
 
Lycoming's standard best economy mixture setting is peak EGT at 75% power or below. Power is manifold pressure and RPM, not some arbitrary altitude. Set power and run at peak or lean of peak right down to sea level.

As for best power mixture, again there is no arbitrary altitude. Assuming good temperatures, it's perfectly OK to lean to best power (aprox 100 ROP) at WOT and 2700, at any altitude.
 
Approach/Landing
Don’t go full rich on final, it is very hard on engine​

Why is this? It's hard to think any movement of the mixture control at all is "very hard on the engine" at idle power. What's so special about final?

- mark
 
Approach/Landing
Don’t go full rich on final, it is very hard on engine​

Why is this? It's hard to think any movement of the mixture control at all is "very hard on the engine" at idle power. What's so special about final?

- mark

It would be almost equivalent to taxiing around with full mixture. Fouled plugs/ deposits.
 
It would be almost equivalent to taxiing around with full mixture. Fouled plugs/ deposits.

Sorry, I have to add $A0.02 here.

The plugs aren't going to foul in the short time spent in the circuit or on final. Even if they did, that'd be inconvenient but not "hard" on the engine. Unless the pilot is in the habit of making long power-off approaches, things in the chambers will be hot enough not to leave any deposits.

Additionally, if a go-around is needed, it'll probably be at short notice so it's best the engine be ready for it. For the same reason, we move the prop control fully forward once the RPM have started to drop.

Yes, it's possible to leave that stuff until the go-around actually happens. But the pilot will suddenly be busy, and it's too easy to miss something. That would be tough for the engine.
 
Approach/Landing
Don’t go full rich on final, it is very hard on engine​

Why is this? It's hard to think any movement of the mixture control at all is "very hard on the engine" at idle power. What's so special about final?

- mark

Mark, the issue is running the engine rich, which due to the lead is really hard on the engine. Same goes for why Mike recommends aggressive leaning on the ground/taxi. His position is that if you forget to enrichen and the engine runs rough as you descend (or are on final) that a properly trained pilot will push power, prop, and mixture full forward.
 
I didn't ask that follow up question. I plan to cover a small portion of the top of the fins on both 3 and 4 wrapping an inch down the sides. And I'll keep blocking off until the CHTs are within 10-15 degrees of each other.

Cylinder temperature and cylinder head temperature are not the same. Typically there is no instrumentation for cylinder temperature, and the thermal path from the hot head to the cylinder is inefficient anyway. It has to cross the screw joint, into a material (steel) with a far lower coefficient of thermal conductivity. The head sheds the vast majority of the waste head.

Point is, covering some portion of the cylinder to raise CHT is a lot like warming your ears by putting on your shoes.

Why raise a CHT anyway? Why not lower the hot ones, and gain some headroom for climb?
 
Cylinder temperature and cylinder head temperature are not the same. Typically there is no instrumentation for cylinder temperature, and the thermal path from the hot head to the cylinder is inefficient anyway. It has to cross the screw joint, into a material (steel) with a far lower coefficient of thermal conductivity. The head sheds the vast majority of the waste head.

Point is, covering some portion of the cylinder to raise CHT is a lot like warming your ears by putting on your shoes.

Why raise a CHT anyway? Why not lower the hot ones, and gain some headroom for climb?

I'm still learning and I would say my baffling is 97% of the way there but at some point if there are no leaks I don't see how it is possible to bring all of the CHT temperatures lower. My hottest cylinders 2 and 6 are around 385 maximum during climb except on hot days when they can reach 400 before I use fuel to keep them from going higher (climbing at 130 kts). My understanding is that by blocking off some of 3/4 it will push more air over 1/2/5/6 and provide some help cooling them. Is that incorrect?
 
Sorry, I have to add $A0.02 here.

The plugs aren't going to foul in the short time spent in the circuit or on final. Even if they did, that'd be inconvenient but not "hard" on the engine. Unless the pilot is in the habit of making long power-off approaches, things in the chambers will be hot enough not to leave any deposits.

Additionally, if a go-around is needed, it'll probably be at short notice so it's best the engine be ready for it. For the same reason, we move the prop control fully forward once the RPM have started to drop.

Yes, it's possible to leave that stuff until the go-around actually happens. But the pilot will suddenly be busy, and it's too easy to miss something. That would be tough for the engine.

I agree that the word "hard" as used by Mike was not the best choice of words. Go full rich on final and watch the EGTs, if they are low enough (which they will be) the lead scavenging won't be there. Do it especially at a high density altitude airport and you will eventually foul an aviation spark plug. Ya it will be missing a time or two and you can clear it up but I would just rather avoid it which is why I don't go full rich in the pattern. First thing I do when I apply full power to my engine is look at the EGTs, if I forgot to push the mixture in I would know very quickly.
 
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Mark, the issue is running the engine rich, which due to the lead is really hard on the engine.

where do you guys come up with the stuff. Lead is only an issue when rich???

Lead is lead and is always present. If you want to talk about what temp lead bromide will become vapor, that makes a lot of sense, but concerned about lead when ROP, but not LOP makes no sense to me. From my research, aside from deposits, lead is good for your engine. It lubricates, cools, and increases detonation margin. There is a reason that they put lead in the gas originally.

Larry
 
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I agree that the word "hard" as used by Mike was not the best choice of words. Go full rich on final and watch the EGTs, if they are low enough (which they will be) the lead scavenging won't be there. Do it especially at a high density altitude airport and you will eventually foul an aviation spark plug. Ya it will be missing a time or two and you can clear it up but I would just rather avoid it which is why I don't go full rich in the pattern. First thing I do when I apply full power to my engine is look at the EGTs, if I forgot to push the mixture in I would know very quickly.

lead bromide becomes vapor around 800-1000 degrees and will typically not deposit above those temps. I have never seen my EGTs lower than 1200 in the pattern. Maybe my engine is different. At idle, the temps can get into that range and that is typically when lead deposits are made.

IMHO, leaning aggressively in the pattern is an accident waiting to happen. If I need power in the pattern, I likely need it NOW. Having to remember to go full rich increases the odds of becoming a statistic. There is a reason that pretty much EVERY certificated airframe manufacturer recommends full rich in the landing phase. I landed a couple of weeks ago with serious wind shear (10 kts surface/60 knots at 1500 AGL). My IAS was jumping between 75 - 100 MPH. I needed several LARGE throttle movements to stay safe. You just don't know when you will need aggressive throttle, but I promise that you will appreciate that it works when you need it when near the ground.

Larry
 
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lead bromide becomes vapor around 800-1000 degrees and will typically not deposit above those temps. I have never seen my EGTs lower than 1200 in the pattern. Maybe my engine is different. At idle, the temps can get into that range and that is typically when lead deposits are made.

IMHO, leaning aggressively in the pattern is an accident waiting to happen. If I need power in the pattern, I likely need it NOW. Having to remember to go full rich increases the odds of becoming a statistic. There is a reason that pretty much EVERY certificated airframe manufacturer recommends full rich in the landing phase. I landed a couple of weeks ago with serious wind shear (10 kts surface/60 knots at 1500 AGL). My IAS was jumping between 75 - 100 MPH. I needed several LARGE throttle movements to stay safe. You just don't know when you will need aggressive throttle, but I promise that you will appreciate that it works when you need it when near the ground.

Larry

I get a couple cylinders that will do it. That low point is on final. This is also in a somewhat leaned state.

I think you also might of misinterpreted what I said. I do not lean aggressively in the pattern. I know Mike subscribes to LOP all the way to touch down; I do not, when I am a couple miles out I go rich of peak to my usual climb EGT. When I am in the pattern abeam the numbers I do add more mixture which allows me to jockey the throttle if needed. I was merely saying I do not go full rich as many do. If a guy wants to that's cool with me, I was just pointing out why Mike made that recommendation.

Lastly, "going full rich on final" is also a blanket statement that can be dangerous at a high density altitude airport on some engines.
 

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Perhaps you could expand on how the blocking is installed.

Vic did not go into detail on how to install it. My plan is to install aluminum tape to see if I can get the results I would like and if I can then I'll work on formulating a plan for installing the blocking.
 
Blocking 3-4

You want 2 to be cooler cut the deflector down in front of it, that will cool #2
You want to cool 5 and 6 by diverting air over the cooler 3-4? yes that will work.
I have a mentor that was into CART racing, knows his engines and cooling them, he (and I) have a 3/4 maybe, probably more deflector in front of 3-4 to move the air over them. I tried the aluminum tape and it didn’t work, the deflectors when angled and sized correctly do the job. My #6 went down 15-20f (depends on time of year) my coolest 4 went up about the same. Now within 15f from coolest to hottest. HOWEVER this is based on the fact that my injectors are tuned for aggressive LOP. I hope Mike mentioned that injectors should be tuned before trying to lean successfully? my guess is if not the one closest to peak is running the hottest and the coolest probably the most lean.
When you get it figured out for your plane, let us know what you did to do so.
 
Vic did not go into detail on how to install it. My plan is to install aluminum tape to see if I can get the results I would like and if I can then I'll work on formulating a plan for installing the blocking.

See the sketch below. Tape or baffle rubber applied as in the topmost example should raise cylinder temperature, but it is unlikely to increase pressure, i.e. flow at the other cylinders.

Wraps up the sides per the middle example probably won't increase cylinder temperature, but will increase upper plenum pressure. The reason is an effective inlet restriction at the top of the wrap.

Small bent aluminum pieces can be added to the exit so as to decrease the exit area. If under the head, they may cause the CHT probe to read lower, although the actual overall temperature may not change much. They should increase upper plenum pressure.

I realize you believe your baffling is pretty good, but there are typically many large and small details which can lower CHT. For example, here we're talking about restricting flow to a pair of cylinders to raise flow at the other four, yet you probably have two or three blast tubes wasting pressure.
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See the sketch below. Tape or baffle rubber applied as in the topmost example should raise cylinder temperature, but it is unlikely to increase pressure, i.e. flow at the other cylinders.

Wraps up the sides per the middle example probably won't increase cylinder temperature, but will increase upper plenum pressure. The reason is effect inlet restriction at the top of the wrap.

Small bent aluminum pieces can be added to the exit so as to decrease the exit area. If under the head, they may cause the CHT probe to read lower, although the actual overall temperature may not change much. They should increase upper plenum pressure.

I realize you believe your baffling is pretty good, but there are typically many large and small details which can lower CHT. For example, here we're talking about restricting flow to a pair of cylinders to raise flow at the other four, yet you probably have two or three blast tubes wasting pressure.
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Thanks, Dan. And you are right I do have two blast tubes for my PMags. Working to make the sealing as tight as possible but I'm definitely fighting against the necessary holes.
 
Lean

I have been leaning all the way to landing for years even though I was not taught that way. I have never had a fouled plug. I don't know what the big deal is about go arounds. Just 3 levers up instead of 2. Practice it and it becomes second nature.
 
I have been leaning all the way to landing for years even though I was not taught that way. I have never had a fouled plug. I don't know what the big deal is about go arounds. Just 3 levers up instead of 2. Practice it and it becomes second nature.

As a counterpoint, I’ve been richening in the circuit for years, and never had a fouled plug either :)

Some go-arounds happen at very short notice. When a new RV pilot bounces a wheeler, the fix is to get out of there before the bounces diverge. There isn’t enough time, or enough hands, to be reaching for the prop and mixture before going to full throttle.

The same applies if a windshear or crosswind get out of limits. The pilot needs instant throttle response, and it may not be there if the mixture is still set for cruise.

I didn’t intend to digress into piloting technique in this thread, and I hope I’m not insulting anyone’s intelligence. But claims such as “hard on the engine” can lead into practices that create safety issues.

To be clear: I’m an advocate of LOP ops, and I’ll lean the engine aggressively when I can. But IMHO the approach phase isn’t the time for it.
 
An observation:

If you have a quadrant, as Tooch probably does, it's an easy sweep of the open hand to go balls-to-the-wall on all three levers on a go-around. For vernier push-pull knobs, not so much. This may affect what pilots are comfortable with when it comes to the mixture setting on final.

I have a quadrant, but I run full forward prop and full rich mixture in the landing pattern, so it's only the throttle in play for a go-around, but if I didn't, it's not hard to shove it all forward at one time.

Honestly my biggest control manipulation worry in a go-around would be the caveat against opening the throttle too quickly on a counter-weighted engine like the IO-540 C4B5. That's supposed to be bad juju.
 
If you have a quadrant, as Tooch probably does, it's an easy sweep of the open hand to go balls-to-the-wall on all three levers on a go-around. For vernier push-pull knobs, not so much. This may affect what pilots are comfortable with when it comes to the mixture setting on final.


Bill is right. I have a quadrant in my 10 but my 7 did not but only had 2 push knobs, no constant speed prop, so it was never a problem for me. It may be different with the 3 push knobs.
 
I have been leaning all the way to landing for years even though I was not taught that way. I have never had a fouled plug. I don't know what the big deal is about go arounds. Just 3 levers up instead of 2. Practice it and it becomes second nature.

You would think so, but there are still many people that crash planes due to fuel exhaustion and the NTSB finds a lot of fuel in the un-selected tank. You would think it would be second nature to switch tanks if your engine stopped spinning, but clearly it doesn't happen every time. The plan may work for you, but doesn't seem universal and folks reading this should consider ALL factors. IMHO you are doing NOTHING harmfull to your engine by running full rich for the 30 seconds that you are in the pattern. Why take such risks to eliminate a problem that doesn't exist. FLight school engines run for 2000 hours with the red knob pinned at full rich and they most always make TBO.

food for thought.

Larry
 
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So returning to topic, why is full rich for landing "very hard on the engine"? Did the speaker offer a reason?

For purposes of discussion, let's assume the airport is less than 1000 MSL.
 
The plan may work for you, but doesn't seem universal and folks reading this should consider ALL factors. IMHO you are doing NOTHING harmfull to your engine by running full rich for the 30 seconds that you are in the pattern.
Larry

"November 814Romeo Victor, you're cleared to land number 4 for two six Right, follow the Biplane ahead, I'll call the base...." Longest 30 seconds of my life.
:rolleyes:

-Marc
 
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So returning to topic, why is full rich for landing "very hard on the engine"? Did the speaker offer a reason?

For purposes of discussion, let's assume the airport is less than 1000 MSL.

Dan, I can't remember the context to Mike's statement. Best I can remember that he was explaining how he sets his mixture when flying his plane. It is a turbocharged twin. He likes to descend lean of peak (if you forget to enrichen the plane will remind you). I think his goal is to remain as lean as possible which has resulted in 2X to 3X TBO for the past 32 years of flying. My bullet points were intended to capture the highlights and as with many areas of flying there are many right ways and as pilots we decide what works (or doesn't work) for each of us.
 
He likes to descend lean of peak (if you forget to enrichen the plane will remind you). I think his goal is to remain as lean as possible which has resulted in 2X to 3X TBO for the past 32 years of flying.

Lean as possible for descent from cruise? Heck, we all do that!
 
I stay very lean coming down from cruise, and go fat on the mix about the time I'm turning final. My reason is to protect the engine if I have to go around at full power - I'm going to be busy flying the plane for the next several seconds and I want to be able to "fire and forget" the engine. It needs to be rich to make full power without detonating. Once I'm down and stable on the rollout, I roll the mix back to lean for taxi.
 
So returning to topic, why is full rich for landing "very hard on the engine"? Did the speaker offer a reason?

For purposes of discussion, let's assume the airport is less than 1000 MSL.

Did not see the presentation but I wonder if it was more about shock cooling since ROP adds cooling to an already low load phase of flight?

Sorry I fly mostly LOP and don't so much believe cooling is going to harm my engine. However I fly mostly in Florida where there isn't much chance for much cooling.
 
I've avoided jumping in on this thread, but I've received a number of private emails asking me to weigh in. So, hear are my opinions, based on 10,000 hours of GA piston experience, as well as looking at close to 2000 RV's.

First, keep in mind that on this forum we are primarily speaking about Lycomings. Mike Bush's experience is primarily on Continentals. Yes, they are different.

First, keep in mind that EVERY ONE of our aricraft is different. Please read that again. I have yet to see 2 aircraft exactly alike, even when constructed by the same builder. I point that out because it seems when someone asks for help everyone wants to point out that their airplane runs differently. Yep, it probably does, and until one closely looks at it, we may not understand why. I still get a kick when someone tries to point out that their particular airplane has been "flying this way for over 200 hours with no problems." Zeesh, we still issue Bi-weekly AD's on a certified fleet that has trillions of hours on it. Our RV fleet is extremely young by any standards.

So, please keep an open mind here, as I do not intend to get into an argument with anyone.

Yes, I did explain to the genleman at OSH that adding some tape or other paraphenalia to cylinders 2&4 as shown in Dan's picture, will in fact help to increase those temps. That is based on experience. It usually does nothing to the other 4 cylinders.

Second, everyone is trying way too hard to keep cylinders below 400 degrees in the climb! Remember I pointed out that Lycomings are different than Continentals. Quit trying to apply the same constraints across both engines. Lycomings will run all day to TBO using 435 in the climb. When Lycoming introduced their LASAR ignition system, it had a CHT probe that would KEEP the CHT's at 435 by advancing the timing in the climb. My RV-6 had that system and went 1800 hours with it. It was clean as a whistle when torn down due to a prop strike, and burned hardly any oil. I've been to the Lycoming factory and spent time with them. They are annoyed that we all keep trying to run them so cool. BTW, for certification purposes they have to run the engine NONSTOP at full throttle with EVERY temp maxed out for 150 hours. We aren't even getting close.

The first advice I give everyone on hot CHT's is to check ignition timing. It's the number one culprit, following by proper airflow. We had an RV-7 come to us this week complaining about high CHT's in the climb, with number 3 cylinder hitting 471 degrees! Yep, that's hot, and need to be corrected. So, first thing we do is check the timing on the O-360. It is at 28 to 28.5 degrees!!! We timed it correctly at 25 DBTDC, and added the washer to cylinder 3 baffling between the rear screw and the baffling, and further opened up the baffling on number 3, as it was tight against the rear of the cylinder. They reported that on the way home all temps were normal, and they are very happy. They also had a big 2" hole in the front baflling pointed at the alternator. We closed that up by more than half. It is important to keep holes into the bottom part of the cowling to a minimum so that the high pressure is on top and allows for good air flow from the top of hte engine to the bottom of the engine.

Next subject---leaning. Before we had all of our fancy gauges, once we reached cruise flight and set power, we pulled the mixture back until it ran rough, and then forward a little until it smoothed out (kind of the way Scott mentioned his wife does it). That pretty much kept us right at PEAK. It worked, and that's the way I've always ran my engines. My current Thunderbolt has 870 hours on it and burns about 1 qt every 12-15 hours. Pretty excellent for an IO-540.

The first thing I do after it starts is to pull the mixture WAY back. It's so far back that if I add any power to taxi I usually have to enrichen it a little. You can't hurt the engine with the mixture control below 75% power. Keeping it lean on the ground stops the lead fouling the spark plugs. Someone already mentioned that lead won't vaporize until about a 1000 degrees. If you look at your EGT's they are more around 900 or less at idle. So keep the mixture leaned ont he ground.

As for approach and landing, I do leave the mixture leaned for descent. Sometimes it requires enrichment during the descent if I've been up in the teens for cruise, and then I do enrichen quite a bit on final, but not full rich. I know it will go to full power easily if I need it, as I've tested it. :) That's a hint--- you should test yours, as they are all different.

So in summary, just like we are all different "people", our airplanes are all different. You need to take a hard look at yours to look for differences. Get another set of eyes on it if possible.

In the end, when it comes to cooling, ignition timing and proper airflow on our STOCK engines are the two primary causes. After that, there are some other things to check for, such as proper fuel flow, especially on injected engines.
Here's a quick test for those of you who are wondering about that one. Set power at 24 squared, cruise flight and FULL RICH, and make a note of the EGT value. Pull mixture back slowly until the engine stumbles. You should see an increase of 175-250 degrees on the EGT. IF not, then it is set up too lean, which could be the injectors or the main nozzles. It's too much to go into detail here.

Other contributing factors can be plenums that are too tight, poor baffling seals around the top of the baffling, poor sealing of the baffling to the nose area and motor mounts, etc.

Actually this whole discussion probably warrants a webinar so we can discuss things better.

One last point--- climbing at 75 knots on a new engine is dumb. Our RV's cool best between 100-110 in the climb. We are redoing the EAA flight test manual to recommend breaking in the engine prior to doing some of the flight testing.

So, there's my .02.

Vic
 
When Lycoming introduced their LASAR ignition system, it had a CHT probe that would KEEP the CHT's at 435 by advancing the timing in the climb.

Vic, can you document that point?

My understanding is that 435 is a preset limit, in accord with Lycoming's operating manuals. As CHT increased, the LASAR system removed advance, so that at 435F, it was running at standard dataplate timing, no additional advance.

From the 540 parallel valve operating manual:

For maximum service life of the engine maintain cylinder head temperatures between 150°F and 435°F during continuous operation.

From the 390 angle valve operating manual:

For maximum service life, cylinder head temperatures must be maintained below 435°F. (224°C.) during high performance cruise operation and below 400°F. (205°C.) for economy cruise powers.

From Unison SL1-96H:

5. Cylinder Head Temperature Control
Automatic timing advance from the LASAR® system may cause cylinder head temperatures (CHTs) to increase as fuel is burned more efficiently within the combustion chamber. Incremental CHT rise due to ignition timing advance from a non-CHT controlled LASAR® system is typically 15 to 20°F. To accommodate LASAR® system installations on airframes with marginal engine cooling or on airframes where engine cooling characteristics have not been determined, LASAR® systems are offered with CHT control circuitry that incrementally reduces the timing advance angle as CHTs approach a preset maximum limit, thereby reducing CHT rise due to advanced ignition timing. If ignition timing advance is reduced by the CHT control feature, engine performance improvements resulting from optimized ignition timing will be reduced. In extreme situations where the engine continually operates at maximum cylinder head temperatures, LASAR® will command the same ignition timing as provided by conventional magnetos, resulting in comparable engine performance.
 
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yes, it allowed the temp to remain at 435. You are right in how it did it. But it kept it nailed. I had hundreds of hours flying it.

As as you can see form your other specs, 435 is just fine. That is the optimum range.

Everybody trying to get them below 380-400 in a climb, especially on hot days, is just wasting time. It's not necessary.

My experience across multiple IO-390 installations is that the oil temp will run hotter in those, sometimes approaching 215-225F in a climb. But then it cools back down to 195 or so in cruise, which is just fine, too.

I keep my oil temp in the 10 between 185-190, and rarely see 195 after a fuel stop on hot day, taking off heavy, with CHT's never exceeding 400.

Vic
 
yes, it allowed the temp to remain at 435. You are right in how it did it. But it kept it nailed. I had hundreds of hours flying it.

That means you had 435 CHTs while at 25 BTDC.

Everybody trying to get them below 380-400 in a climb, especially on hot days, is just wasting time. It's not necessary.

With respect, I think that's very bad advice.
 
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Dan, respectfully, it is not. I've been to the factory and spent time with them. I would NOT give bad advice to anyone.

I also have enough experience across many different isntallations at those temps and have seen the engine teardowns.

But I am done here. I was asked to weigh in and I did that.

Vic
 
Dan H and Vic (and others),

I respect both of your opinions as you both seem to know what you speak of via experience, research, or both. For a mere peon in the GA world, it certainly can be confusing reading all of these opinions from Mike Busch, George Braly (from GAMI), the Lycoming manual (which still has old info in it), and other "experts".

Let's see if these are things we mostly can agree on - I'd love to be corrected where wrong for my own knowledge! For a simpleton like me do these techniques work?

(1) It's good to run lean at low power settings on the ground after engine start. Should help prevent lead fouling.

(2) It's good to keep those CHTs reasonably low. Pick your number - 400, 380, 435. Personally I try to stick to 400* or less, but the key is to keep an eye on the temps if you have the means. More fuel and higher climb speeds (lower climb angles) will help to lower the temps.


(3) Not good to run right at peak EGT at higher power settings (75% and above). Too much cylinder pressure.

(4) At typical cruise settings (lets say 55 - 75% power) either run 75 degrees (or more) ROP or go LOP if you can. At lower power settings you can't damage the motor with the big red know of doom.

(5) Descending "leaned out" is okay if you remember to add mixture for a go around.

Do these all sound safe and healthy for the engine? Not being sarcastic - just want to make sure I have the basics down.

Cheers,

Rick
 
I flew Navajo's professionally. They're angle valve cylinders (turbo fed), and have a reputation of running hot. It was quite common to see the CHT slightly over 400* in the climb and slightly under 400* in cruise. Engines made TBO, and I can't remember them changing cylinders early.

Based on that experience, it sounds reasonable that 410*-435* in climb, and 380-ish in cruise is okay.

Mixtures went full forward with gear down (on downwind or glideslope intercept) but stayed in the cruise setting through descent and initial approach.

The more I read and the more people I talk to, I'm really coming to the conclusion that there's not much we can do to hurt a stock 4 cylinder Lycoming. Maybe with high compression pistons, turbos, gearing (GO-480?) or too much ignition advance, there might be more concerns. These are pretty simple, reliable and bullet proof engines. Don't think we need to get too excited.
 
I would like to remind folks of the advice from Don Rivera of AFP regarding setting idle mixture. Leaning on the ground is generally not necessary when idle is correctly set. See this educational thread from years back when Don was still on the forum:

https://vansairforce.net/community/showthread.php?t=94002

Erich

Emphasis on the word general above. Probably fine for many but not all.

Read his post #38. Many people fly from high density altitudes. A 10,000-12,000 ft day is fairly common around here and I'm not even in tall country. No way am I setting it so I don't have to use the red knob on the ground. Don't want to go down to sea level and be caught with my pants down. :D

I guess in my mind I don't see any downsides to leaning on the ground. I do see some potential ones without. Using the red knob on the ground and in the air (even in the pattern) is just normal ops for me, I'm used to it. Not knocking anyone else's approach, just wanted to try and clarify what Mike was suggesting as I was at his presentation as well.

If anyone wants to really know what he said in his own words go to YouTube and watch the webinars called "leaning basics" and "leaning the advanced class".

P.S. Don still has one of the best posts on this entire site when I read his detailed description of why FI engines idle rough while hot.
 
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Dan H and Vic (and others),


Let's see if these are things we mostly can agree on - I'd love to be corrected where wrong for my own knowledge! For a simpleton like me do these techniques work?

(1) It's good to run lean at low power settings on the ground after engine start. Should help prevent lead fouling.

(2) It's good to keep those CHTs reasonably low. Pick your number - 400, 380, 435. Personally I try to stick to 400* or less, but the key is to keep an eye on the temps if you have the means. More fuel and higher climb speeds (lower climb angles) will help to lower the temps.



(3) Not good to run right at peak EGT at higher power settings (75% and above). Too much cylinder pressure.

(4) At typical cruise settings (lets say 55 - 75% power) either run 75 degrees (or more) ROP or go LOP if you can. At lower power settings you can't damage the motor with the big red know of doom.

(5) Descending "leaned out" is okay if you remember to add mixture for a go around.

Do these all sound safe and healthy for the engine? Not being sarcastic - just want to make sure I have the basics down.

Cheers,

Rick

Yes, all is good, except, BELOW 75% power it is OK to run at peak.

Vic
 
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