Life with 262 - next question

[geoffb]

Is 50 degrees F rich of peak TIT the default, safe mixture setting for cruise power say 65 percent?

The engine is equipped with GAMIs but doesn't run smooth lean of peak TIT.  Seems to run cool, but I haven't had it above 10,000 yet, waiting on my ADS-B equipment.

[StevenL757]

3 hours ago, geoffb said:

Is 50 degrees F rich of peak TIT the default, safe mixture setting for cruise power say 65 percent?

The engine is equipped with GAMIs but doesn't run smooth lean of peak TIT.  Seems to run cool, but I haven't had it above 10,000 yet, waiting on my ADS-B equipment.

Although I don't own a "K", curious as to...

• What type of spark plugs you're using...iridium finewire, or massive?
• How old are the plugs?
• What type of ignition harness are you using, and how old is it?
• When was the last time a fuel setup was accomplished?

@gsxrpilot, @anthonydesmet, and/or @kortopates came up in my head as better folks to weigh in here; but my initial thought ran to plugs.  You should be able to run LOP optimally with a gold seal ignition harness or equivalent, and iridium finewire plugs (without opening the proverbial Pandora's LOP/ROP Box on the subject).

[geoffb]

227 SNEW on all the above.  Champion massives.

[gsxrpilot]

At 65% power or lower, you can run wherever you like. You can even run at peak EGT. 

You might want to get on the Savvy Analysis site and download their Flight Test Profile. Assuming you have a good engine monitor, go fly that test profile and you'll know why your engine isn't smooth LOP. Then you can do something about it.

[jlunseth]

33 minutes ago, gsxrpilot said:

At 65% power or lower, you can run wherever you like. You can even run at peak EGT. 

You might want to get on the Savvy Analysis site and download their Flight Test Profile. Assuming you have a good engine monitor, go fly that test profile and you'll know why your engine isn't smooth LOP. Then you can do something about it.

That's a good place to start. Fuel flows have to be even. The first place I always look is the magnetoes, plugs and harness. If the spark is weak you will not run LOP no matter how well balanced your fuel flows are. But then I have GAMIs and my flows are pretty good so that probably alters my perspective. 

[milotron]

Ignition has a big impact. I switched to fine wire and noticed a big difference. I have one mag at 450 hours that is notably weaker than the other which also impacts LOP ops for me.

[carusoam]

Watch a got for an engine monitor?

Familiar with savvy?

Get ready to push data over to savvy, and share here...

M20Ks are much better at running LOP than many birds...

But, all it takes is one dirty fuel injector to make that a challenge...

Engine monitors are really good at sorting out details like this...

 

Best regards,

-a-

Edited January 20, 2021 by carusoam

[anthonydesmet]

+1 for gxrpilot’s recommendation to get on Savvy and start with the flight test to baseline your performance.

I’m also a member of their analysis pro. It’s great to have someone like kortopates to review your data with.

i also run 65% power 99% of time.  Sometimes ROP and sometimes LOP depend on mission (best power for speed or best fuel for range). Knowing whether you can run LOP gives you additional capability when planning cross countries.

ive tried 75% power a couple times but in my opinion I didn’t think the added fuel flow and speed increase was a big enough impact to coming close to the tail fin impact zone.

 

P.S. notice I also stayed away from cylinder life subject....hah!

[Z W]

2500 RPM, 28"MP, lean to peak TIT, 11.5 GPH.  Works great.  Can lean about another .5 GPH, which is 25-50 degrees LOP, before it gets rough on our bird, but speed rapidly seems to drop off, and the engine doesn't seem as happy. 

Crack the cowl flaps as necessary to keep all cylinders under 380 degrees.

Your mileage may vary.

[carusoam]

Great pirep for Paul and Savvy!

Thanks for sharing it, Smut! (With all due respect! )

Best regards,

-a-

 

[Will.iam]

Zane what is your tit temp at that setting? I run 30” 10.5 FF and 2200 rpm and my tit is 1545, if I increase the RPM to 2500 the tit goes up passed 1600. I either have to reduce FF or MP to keep tit lower with 2500 rpm. 

[Z W]

Usually around 1550-1600, depending on outside air temp and altitude.  1650 TIT is max for continuous operation and I've never seen it hit that with those power settings.

[Seth]

On 1/19/2021 at 9:22 PM, milotron said:

Ignition has a big impact. I switched to fine wire and noticed a big difference. I have one mag at 450 hours that is notably weaker than the other which also impacts LOP ops for me.

Tempest Fine wire made all the difference between a slight rumble and an extremely smooth LOP operation with the NA 300 HP IO550A in the Missile.

The champion massives were fine ROP but not LOP.

 

-Seth

[Will.iam]

4 hours ago, Seth said:

Tempest Fine wire made all the difference between a slight rumble and an extremely smooth LOP operation with the NA 300 HP IO550A in the Missile.

The champion massives were fine ROP but not LOP.

 

-Seth

I have tempest fine wire but i think my problem is the mags as the left rises higher than the right so i know for a fact they are not timed evenly and one is more advanced than the other. I will try to get them balanced this month but at next annual (aug) I’m seriously looking at putting a surefly electronic ignition just for the better lop ops with hopefully lower TIT from the better burn from the surefly and smoother low idle benefits.  

[geoffb]

Bringing this back up.

Wanting to learn more about the TIT.  Is continuous operation between 1600-1650 hard on the turbocharger?  I know the limit is 1650 continuous, but the CHT limit is 460 and no one recommends running there.  Just curious about keeping it healthy.  At FL190 on Tuesday, 65% by the chart at 2500 RPM, about 12.2 gph, the highest CHT was 352, lowest 336.  Number 3 is hottest, 6 coolest.  So the engine temps are good with cowl flaps shut.  If I leaned more, my TIT would exceed 1550.  Peak CHT was close to 1650.

My question boils down to should we pour a bit more fuel in to keep the TIT to some value below red line in exchange for longer turbo and maybe exhaust life?  Or does experience show they can run along at 1650 without harm?

 

 

[kortopates]

The best mixture guidance for both ROP and LOP is here: https://gami.com/gamijectors/AFMS - GAMIjectors Rev IR.pdf

For TIT we don't like to see TIT being run continuously above 1600F and suggest 1600F as a cutoff to promote maximum exhaust component longevity. I personally target for 1580F max to give me a little buffer. Afterall Turbo OH's typically cost more than a couple cylinders and repacing thin or even cracked sections of exhaust gets expensive as well. 

Also whatch out for TIT probes that loose their accuracy over time. Both EGT and TIT probes suffer from tip erosion, literally from being torched by exhaust pulses. EVentually they'll become erratic and clearly signal a burnt out probe. But often they start to indicate progressively lower than actual before they become erattic so it good to periodically re-verify what peak really is - since its the degrees from Peak that important. Rocket Engineering even discusses a TIT probe calibration because they give mixture guidance on TIT temperature numbers. Personally I never thought that was good advice but all of the industry it seems, tries to over simply with simple proxies IMO without actually educating the pilot properly on how to manage their engines.  

[geoffb]

Thanks Paul.  Finally found where they buried the data port on my JPI700, so I'll get some data downloaded.

[Will.iam]

On 1/19/2021 at 8:22 PM, milotron said:

Ignition has a big impact. I switched to fine wire and noticed a big difference. I have one mag at 450 hours that is notably weaker than the other which also impacts LOP ops for me.

How do you know which mag is weaker? Does the weaker mag have a higher or lower egt temp than the other?  I ask because i thought one of my mags was not timed the same as the other because my left mag the egt were 50degrees higher than my right mag. But i got the mags checked and they are within 1 degree of each other in timing. Can a weaker mag make that difference?

[milotron]

Hi, for me the difference was a very noticeable increase in engine roughness(?) while lean of peak and with switching the mags on or off. It could be other ignition related items to that particular mag, like the harness or plugs also.  My left mag that had high hours was just IRANed and it is noticeably smoother now. The TIT went down a bit also. I think the TIT went down about 20 degrees based on the same power settings before and after the repair, not accounting for environmental conditions.

There was a number of degraded parts for that mag if I recall, including worn down cam, points and some other bits showing their age.

Certainly when you run on one mag, LOP and at altitude all the EGTs and TITs jump due to the less complete, or later in-cylinder combustion and more flame out the exhaust. With your EGTs being that much higher, it could suggest an issue with the ignition either in the mags or wires themselves.

[Will.iam]

50 minutes ago, milotron said:

Hi, for me the difference was a very noticeable increase in engine roughness(?) while lean of peak and with switching the mags on or off. It could be other ignition related items to that particular mag, like the harness or plugs also.  My left mag that had high hours was just IRANed and it is noticeably smoother now. The TIT went down a bit also. I think the TIT went down about 20 degrees based on the same power settings before and after the repair, not accounting for environmental conditions.

There was a number of degraded parts for that mag if I recall, including worn down cam, points and some other bits showing their age.

Certainly when you run on one mag, LOP and at altitude all the EGTs and TITs jump due to the less complete, or later in-cylinder combustion and more flame out the exhaust. With your EGTs being that much higher, it could suggest an issue with the ignition either in the mags or wires themselves.

Thanks for tge info.
I’m looking at getting a surefly electronic ignition and want to replace the more worn out Mag but would prefer to put the surefly on the right side as it is so much harder to access than the left mag due to space. 

[carusoam]

 

 

Interesting question... check your logic... (or check my logic...)

Which mag is stronger or weaker...?  (A state of wear)

 

For the most part... they either work or don’t work...  (from JPI data, and run-up)

From the logs... they have zero hours or 500 hours since OH, rebuild, or some maintenance... (check your logs)

The electronic mag, typically replaces the Left (?) mag that is set up for engine starting...

So picking the weaker mag to replace... May have a limitation...

 

Sounds like the new electronic mag is going in the left mag location... (based on tradition... and how the switch is wired...

Keep your eyes open... to not accidentally select something that may be penny wise, yet pound foolish...

Selecting the stronger mag today, will be completely different in the 500 hours cycle...

This will become important at a later date while troubleshooting a starting problem... at a far from home field...

 

PP thoughts only, possibly mis-understanding what the question is really asking...

Best regards,

-a-