NOtes on a new a3B6 engine

[HopePilot]

Jetdriven -

Any update? I tried to send you a message, but Mooneyspace wouldn't let me (said your account couldn't take any new messages). I'm still interested in doing this and hearing what you got out of it. Also, what to know what was involved.

[HopePilot]

Jetdriven - I see you're online. Any idea why our engines were shipped with the optional 20 degrees instead of 25?

[jetdriven]

Lycoming SI 1325A allows 20 degrees of timing. From the SI: "Certain advantages in engine operation have been found by changing engine timing from 25° BTC to 20 BTC and reducing the lag angle to 15° on impulse coupling magnetos and 15 retard angle on retard breaker magnetos whichever is applicable. Significant improvements in engine operating characteristics are achieved in above listed aircraft engine installations particularly in the areas of normal operation and cold weather starting. During cruise operation, cooler cylinder head temperatures can be expected resulting in improved service life of intake and exhaust valves. During full throttle operation the new spark setting will reduce possibility of detonation during extreme cold weather operation. Consequently this modification has been incorporated in the production of new engines and may be incorporated in engines in service as follows:" You basically change the lag angle from 25 degrees to 15 degrees on the left mag, change the timign to 20 degrees, and stamp the data plate for 20.

The A3B6D is not allowed 20 degrees, but the A3B6 is. My testing has revealed that 25 degrees is slightly more power than 20 degrees, but 23 degrees is optimal on the roller cam A3B6. 23 degrees timing is about 20 degrees F cooler CHT than 25 degrees timing and the fastest ROP full throttle, 2700 RPM sea level speed of all. It also allows the best compromise between sub-380 CHT's in normal operation and good LOP performance.

If you have a flat-tappet A3B6 engine there may be significant gains in performance with 25 degrees of timing. There sure was with the A3B6D. However, the roller-cam A3B6 does not respond as well to 25 degrees. I think the cam has slightly different specs than the flat-tappet cam.

Per Lycoming, it is legal to undo SI1325A and run 25 degres timing with the correct P/N Bendix S4LN-1227 (Bendix 1200 mags) or Slick mags.

My Bendix 1200 mags arrive tomorrow. I plan to instal them next week for better relaibility and marginal improvements in LOP performance as they have significantly more spark energy to light the lean mixture.

[HopePilot]

I'd like to go for 23 degrees, even though my A3B6 is flat-tappet. My left Magneto came with Slick 4372 and right is Slick 4370, so can I just replace my Slick 4372 which is the one that's a 20 degree mag? Still trying to learn, so I may have this wrong. My mags only have 250 hours, so if I can use the 4370, I'd like to.

Would I need to have them both set for a specific lag angle before the engine timing was changed to 23 degrees?

[jetdriven]

The correct LH Slick magneto for a 25 degree A3B6 is a Slick 4373. It has the 25 degree lag angle on the impulse coupler. Your 4370 magneto works with either (it has no impluse coupler).

Legally you must change the mag to a 4373 to run the timing at 25 degrees, but I can say that the 4372 mag runs fine at 23 and 25 degrees as well.

I am switching to Bendix mags this week.

[Txbyker]

I just crossed the 50 hour point on my new A3B6. I am about to switch from 100w mineral to 15w-50 Aeroshell. Question is about temps. My CHT, EGT, and oil temp is very predictable but it is not coming down. #1&4 run 380 CHT and #2&3 run 340-350. This is at 8000 ft, 0-6 OAT, and 125 ROP. Am I impatient in thinking the temps should have dropped by now? Oil consumption has slowed signifcantly and runs 190 degrees.

Russ

[bumper]

Russ,

 

When I put an A3B6 in my Mooney, I had a similar problem. Shop that did the engine swap did not seal all the little cracks and holes where upper deck air could sneak down to the lower deck without going through cylinder fins. Tube of silver gray silicone caulk and a scrap of aluminum flashing (to stick on here and there with caulk to block the larger gaps), and temperatures dropped significantly.

 

A suitable short length of plastic hose can extend the tip of your caulking gun to get into tight spots. Slip a washer over the extension hose so that it jambs the extension hose up onto the tapered caulk nozzle and hold tightly in place while applying caulk.

 

bumper

[KSMooniac]

Don't use the Aeroshell 15W-50.  There are much better choices for our engines such as the Phillips 20W-50, or straight Aeroshell 80 or 100.  Plus Camguard with any of those.

[jetdriven]

I just crossed the 50 hour point on my new A3B6. I am about to switch from 100w mineral to 15w-50 Aeroshell. Question is about temps. My CHT, EGT, and oil temp is very predictable but it is not coming down. #1&4 run 380 CHT and #2&3 run 340-350. This is at 8000 ft, 0-6 OAT, and 125 ROP. Am I impatient in thinking the temps should have dropped by now? Oil consumption has slowed signifcantly and runs 190 degrees.

Russ

 

 

Russ, a ROP operated M20J is going to run 340-350 CHT in the mild months, and 380-400 in the summer. Ours has perfect baffles and it does too.  Its just the way its designed.  LOP subtracts 20-30 degrees CHT.

[Txbyker]

Thanks. The A3B6D ran 330's. I was thinking baffling and oil. I have all new baffling too.

[PTK]

Don't use the Aeroshell 15W-50. There are much better choices for our engines ...

According to whom? Opinions are plenty and cheap.

Russ, as you know, Lycoming is the single authority on your new engine. SI1014M outlines lubricating oil specifications.

There are excellent oil formulations that meet and exceed these specs. No need to contaminate your engine with additives of any kind.

[N601RX]

Interesting, I'm about to pass 25 hrs on a field overhaul on my F model. On the 1st breakin flight in January it briefly touched 400 on the initial long climbout and then settled in at around 370. The oil briefly hit 215. After about a hr they came down in the 330's. and the oil 190. Now in cruise they run 310-320 and the oil stays around 190. LOP they will go under 300 ocasionally. Oil usage seemed to stabalize at around 10 hrs. My baffleing is in good shape, but not perfect. There are some small gaps that could be sealed. The numbers all came from a new JPI 830.

My cylinders were 1st run cylinders that were overhauled and reused. The pistons were superior and the rings were eci. Based on what I read about J's I thought they would be cooler than my F. My oil cooler has been relocated to the rear of the engine.

[Txbyker]

Byron, where are your temps these days around Houston OAT? Did you get the gami spread closer and are you running LOP?

[Becca]

Byron, where are your temps these days around Houston OAT? Did you get the gami spread closer and are you running LOP?

 

GAMI spread is still way off compared to old engine, one injector just continuously runs a lot richer than the rest.  We've swapped injectors, cleaned injectors, replaced injectors, still had this same problem.  I am afriad we are going to end up having to spring for a set of GAMI injectors   our old engine had a no problems with this.

 

Our temperatures in Houston are still not up to "summer temps" for comparison, but the engine is running a lot cooler now.  It took a lot longer than I personally expected to break in, though.   When we flew to Florida and Bahamas over Christmas we had no problem keeping all 4 under 360 CHT.  Of course we had other problems -- like flying into KLEE at night on only one mag - can't say enough good things about how they fixed our problem and turned us around in no time!   Next month we'll be doing a couple air races, that will provide some good data points.

Our current concern on the engine is the last few oil analysis has showed high iron (e.g. close to 100 ppm when adjusted for 50 hrs).  Usually you get high metal at break in but we are concerned we are still seeing this with about 150 hrs on the engine.  We contacted Lycoming and we are going to do one more oil change after next 25 hrs and see where we are.  Also higher than expected chrome.   We're not seeing any magnetic metal in the filter above normal.  We borescoped at annual last month and didn't see any signs of wear.  But we certainly want to see what's going on before our warranty expires in August. 

[aaronk25]

According to whom? Opinions are plenty and cheap.

Russ, as you know, Lycoming is the single authority on your new engine. SI1014M outlines lubricating oil specifications.

There are excellent oil formulations that meet and exceed these specs. No need to contaminate your engine with additives of any kind.

Lol.....it will be years before Lycoming changes there position. Isn't it also a bit odd that when you follow the mfg operating recommendations that they tell you to overhaul the IO360 at 2000 hours and in Mike Busch's case the continental IO520 turbo engines at 1400 hours but he is more than double over haul time with 9 out of 12 original cylinders when operating on 100w and cam guard as well as LOP.

Seems to me the major engine mfg have there head up there you know where and continue endorseing that cht temps upto 450 ar OK and 50 rop is the best place to operate you aircraft. They make good engines for the most part however, probably due to their lawyers they are slow to change ANY operating guidelines.

Some pilots are just as hard headed as the mfg. Do yourself and you engine a favor run a non syn, oil a and cam guard, you might just have the same results as mike did and enjoy alot of time past TBO and keep some hard earned money in your wallet.

[OR75]

Seems to me the major engine mfg have there head up there you know where and continue endorseing that cht temps upto 450 ar OK and 50 rop is the best place to operate you aircraft. They make good engines for the most part however, probably due to their lawyers they are slow to change ANY operating guidelines.

Some pilots are just as hard headed as the mfg. Do yourself and you engine a favor run a non syn, oil a and cam guard, you might just have the same results as mike did and enjoy alot of time past TBO and keep some hard earned money in your wallet.

iwon't disagree with you. however, let's not forget that their lawyers position is based on the many lawsuits that they would incur if anything happened. Put yourself in their shoes, what would they have to gain to change the guidelines ?

same goes for the FAA. It is frustrating they move so slow. We are still using engines used in automobiles about 50 years ago.

[201er]

Seems to me the major engine mfg have there head up there you know where and continue endorseing that cht temps upto 450 ar OK and 50 rop is the best place to operate you aircraft. They make good engines for the most part however, probably due to their lawyers they are slow to change ANY operating guidelines.

I don't think I've ever seen engine manufacturers endorsing 50 ROP. They usually suggest peak or 100ROP for best economy and best power. However, a bunch of instructors have taken it upon themselves to just average the two out and suggest 50ROP to students with no idea what they are talking about. Then the students treat it as the word of God cause that's how they learned.

[PTK]

Aaronk25, where are you getting this info that Lycoming endorses 50 rop and 450 cht? Just curious.

[aaronk25]

What does Lycoming put as a redline on cht....450 not to exceed 500.

[PTK]

That's redline only! In my airplane redline is 475. I keep them <380. They never told you to operate cht's at redline! In fact they tell you 400 or below. Read Lycoming SI 1094D!

[danb35]

Aaronk25, where are you getting this info that Lycoming endorses 50 rop and 450 cht? Just curious.

http://www.lycoming.com/support/troubleshooting/resources/SSP700A.pdf

 

"For optimum service life, Lycoming recommends operating 50 degrees rich of peak EGT or TIT."  Page 2, near the bottom of the second column.  They admittedly don't address CHTs, though the chart included in that same publication confirms that they're highest at 50 ROP.

[PTK]

They are referring to a cruise setting in a na engine. The power is low enough and makes no difference where your mixture is. In the next sentence they tell you that for the TIO-540-AE2A the savings are approx 2-3 gph compared to peak or lop. Again they are referring cruise sertings at sufficiently low power. This is consistent with their recommended 65% cruise power settings specifically for that engine as well.

[danb35]

They are referring to a cruise setting in a na engine.

Since TIT only exists on a turbocharged engine, I'm going to have to say you're wrong about their referring to an NA engine.  There's no reference in there to a limitation on the power setting, nor even to this recommendation applying in cruise.  You may be assuming this, but they don't say it, or even clearly suggest it.

[PTK]

From Lycoming's article you quoted:
"Lycoming recommends cruise operation at peak EGT or TIT, which is the point where the best economy range starts."

From Lycoming's operation recommendations for the TIO-540-AE2A:
"Lycoming recommends that a cruise setting of 65% power be used..."


They clearly state CRUISE operation and peak EGT OR TIT. To me this indicates na OR turbocharged?

Which part of this isn't clear?!

Anyone is free to pick and choose fragments out of context.

[danb35]

From Lycoming's article you quoted:

"Lycoming recommends cruise operation at peak EGT or TIT, which is the point where the best economy range starts."

Right, which is immediately followed by the recommendation for 50 ROP, which doesn't limit the recommendation to cruise.  Did they mean for that recommendation to also apply to cruise flight?  Who knows?  That would suggest to me that the 50 ROP recommendation was for non-cruise ("we recommend peak for cruise, and 50 ROP for everything else"), but that makes even less sense.  It sounds like you now agree, though, that this recommendation isn't restricted to NA engines, as you indicated a few posts up.

 

Lycoming's recommendations on engine management are highly inconsistent at best, and utterly nonsensical at worst.