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Old 12th Apr 2018, 22:30
  #281 (permalink)  
 
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The point is, there are rich and lean mixtures. it is incorrect to say “all mixtures are lean”, which was what I was responding to.
The only mixtures that you can achieve on a conforming engine are lean. To put the concept another way, the only mixtures that can sustain combustion are lean of a F:A ratio of 1:0 (I.e. Pure fuel). Peak EGT happens to be a very useful reference. But I suspect we're disagreeing merely on terminology rather than substance.

You don’t know precisely where each cylinder is. The assumption is that the leanest cylinder is within 25F of the indicated EGT when using the thermocouple on the collecter. The recommended best power setting for the engine is 50ROP so that is where our minimum 75ROP.
That's a big assumption.

My engine has the original CHT gauge as well as the EDM. The original gauge rarely shows above the bottom of the green range. Meanwhile, on the other side of the engine at the front, my hottest cylinder is much, much hotter.

Some serious questions:

Have you ever looked at plots of CHT and ICP against mixture?

If yes, do you believe them or disbelieve them?

If you believe them, why would you be unconcerned about the prospect of cylinders running 50F ROP?

If you disbelieve them, why?

Have you ever had a problem with a cylinder before TBO? i.e. Needing work on the valves or outright replacement due cracks etc?

Rod: Nobody from APS said what you allege. Find a quote and post it, or shut up.

Last edited by Lead Balloon; 12th Apr 2018 at 22:46.
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Old 12th Apr 2018, 23:51
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The statement about sea level at 16000 feet wasn't mine, I was pointing out that the aircraft had to be turbocharged. I would think that it is a Matrx or Meridian, most probably Meridian due to the altitude.

The engine is a twin turbo unit. Which leads to the question of why twin, other than making it nearly impossible to carry out adjustments.
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Old 13th Apr 2018, 01:12
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Originally Posted by Lead Balloon View Post
The only mixtures that you can achieve on a conforming engine are lean. To put the concept another way, the only mixtures that can sustain combustion are lean of a F:A ratio of 1:0 (I.e. Pure fuel). Peak EGT happens to be a very useful reference. But I suspect we're disagreeing merely on terminology rather than substance.

That's a big assumption.

My engine has the original CHT gauge as well as the EDM. The original gauge rarely shows above the bottom of the green range. Meanwhile, on the other side of the engine at the front, my hottest cylinder is much, much hotter.

Some serious questions:

Have you ever looked at plots of CHT and ICP against mixture?

If yes, do you believe them or disbelieve them?

If you believe them, why would you be unconcerned about the prospect of cylinders running 50F ROP?

If you disbelieve them, why?

Have you ever had a problem with a cylinder before TBO? i.e. Needing work on the valves or outright replacement due cracks etc?

Rod: Nobody from APS said what you allege. Find a quote and post it, or shut up.

They and they did but as i said and like the other post and also comments by yourself they been deleted strange that hey.
Please tell me why i can no longer find post by john deakin ?
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Old 13th Apr 2018, 01:46
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As the piston moves upward it will come to a point were the piston will no longer move. Will call this X. The crank will still move in the same diection with no movement of the piston
Since you love to be pedantic, what you mean to say is that there is no detectable piston movement. Whenever the crank is rotating there will always be piston movement. Simple geometry.
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Old 13th Apr 2018, 02:11
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Not sure that is true Megan, the piston does momentarily stop whilst thevrod angle changes.
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Old 13th Apr 2018, 02:27
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Originally Posted by megan View Post
Since you love to be pedantic, what you mean to say is that there is no detectable piston movement. Whenever the crank is rotating there will always be piston movement. Simple geometry.
Wtf
Omg you really dont understand basic engine construction and operation do you.
The pistion moves in an up ward stroke. When it gets to the top there is a degree ( variable with crank/rod stroke and lengh)
This is a dead zone when the crank is rotating and zero movement of the piston.
This movement between the two must be half to get the true tdc. Easy when the head is removeable harder but not inpossible when the head is attach.
Im really supprised at your superior avaition maintenance skills and knowledge you didnt know this basic fact.
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Old 13th Apr 2018, 04:07
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They and they did but as i said and like the other post and also comments by yourself they been deleted strange that hey.

Please tell me why i can no longer find post by john deakin ?
Not deleted.

You can no longer find posts by John Deakin because he didn’t post.

You are confused, as usual.

You meant Walter Atkinson. Try a search of that name. Heck, I even posted in this thread a link to a thread that contains posts by him and you.
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Old 13th Apr 2018, 04:36
  #288 (permalink)  
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Oh well the bus driver has almost got it right.
Rod the Con,
I have got it exactly right, it is your reading and comprehension that is the problem, not to mention your writing.
As a "bus driver", I will back my experience in producing and tuning high performance race engines of the "old school" variety any day, against you.
And I certainly wouldn't knowingly let you anywhere near any aeroplane (or any other machinery) that I owned or controlled.

OK, so the last detectable upward motion rotating forward, and the last detectable upward motion rotating backward, then split the difference. thanks, I just couldn't get what you were trying to describe the first time.
A Squared,
Take it from somebody with a lot of relevant engineering experience, what I described will be more accurate in determining TDC than that described by Rod. Incomprehensible as it may seem to him, some/most "bus drivers" have other qualifications, and in this case, quite extensive experience -- with the silverware to show for it.
Tootle pip!!

Last edited by LeadSled; 13th Apr 2018 at 04:47.
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Old 13th Apr 2018, 04:53
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Omg you really dont understand basic engine construction and operation do you
Sure do, it's just you who doesn't understand geometry. At .0000001° prior to TDC the piston is still moving upwards, at 0° (TDC) the piston stops, and at .0000001° past TDC the piston is in downward motion. Crank/rod stroke and lengh has absolutely nothing to do with it, it's basic geometry.
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Old 13th Apr 2018, 08:45
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Originally Posted by Connedrod View Post
They and they did but as i said and like the other post and also comments by yourself they been deleted strange that hey.
Please tell me why i can no longer find post by john deakin ?
Entered in error
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Old 13th Apr 2018, 08:54
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Could you now review all your other posts in light of your apparently new-found ability to comprehend that you make mistakes?
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Old 13th Apr 2018, 08:54
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Originally Posted by LeadSled View Post
Rod the Con,
I have got it exactly right, it is your reading and comprehension that is the problem, not to mention your writing.
As a "bus driver", I will back my experience in producing and tuning high performance race engines of the "old school" variety any day, against you.
And I certainly wouldn't knowingly let you anywhere near any aeroplane (or any other machinery) that

Good for you bus driver. Ive been around and buildimg hp race engines for a life time as well just for your knowledge.
As for working on your aircraft well once again thats my privilege not to so you never have to worry about that. Ill put my engineering record against yours any day off the week in regrads to aviation maintenance, considering ypur past record on here and lack of knowledge of the regulations. Btw how many maintenance releases have you issued again ?

Now please inlighten megan about tdc and the degress lost seaming you can explain it better than myself and then maybe explain to the folk about crank angle and how it affects inlet flow into the chamber for combustion on a n/a engine.
Thanx in advance ha ha get it lol
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Old 13th Apr 2018, 09:32
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Originally Posted by A Squared View Post
Don't know, only Eddie Dean knows for sure.

Regardless, your entire tangent about whether an engine is at sea level, is just that; a tangent and not a particularly relevant one.

LB asked you which would make more power; an IO-520 with all the knobs forward and the timing advance set to 20 degrees BTDC or the same engine under the same conditions with the advance set to 22 BTDC.

There was a point to the question, but instead of answering the question you started this completely irrelevant tangent about his use of "sea level" (Apparently you didn't know that "Sea level" is the standard reference for engine power output. )



The most charitable assumption would be that he is.

Sorry have not read all posts and not seen such a question.


22 BTDC would as more time to burn more fuel, the more fuel burnt in a sealed chamber has more energy, thus more HP.


Since the piston in a cylinder moves a greater distance in the first 90 degrees of rotation of the crank shaft than the second 90 degrees, it is desirable to have as much fuel as possible burnt in the cylinder at 0.000001 degrees after TDC.


Sea-level you refer is not just the pressure @ 16,000 feet temp will play a large factor - https://en.wikipedia.org/wiki/Standard_sea_level


Using a "pressure" only and insisting it is Sea Level is - well wrong!
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Old 13th Apr 2018, 09:44
  #294 (permalink)  
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considering ypur past record on here and lack of knowledge of the regulations.
Rod the con,
I always love that above angle of yours, as you consistently demonstrate you don't REALLY understand the structure of the Australian aviation legislative framework, and in particular the difference between regulatory, standards and orders, and advisory material.

Much less pick up the conflict and contradictions in so much of that voluminous nonsense peculiar to Australia. Haven't you yet figured out that nobody in their right mind would take your assertions seriously.

For anybody who wants to learn about engine design, particularly inlet and exhaust track design, and related valve/cam/piston relationships, there are quite a few excellent text books on the subject for the curious.

Such reading will be of little real practical benefit in efficiently operating any Otto cycle engine, as fitted to an aircraft.

Tootle pip!!

If you really do know something about high performance engine building, which seems highly doubtful, based on TDC "determination",I sincerely suggest you amend your methods of determining TDC.
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Old 13th Apr 2018, 09:44
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Heck, I even posted in this thread a link to a thread that contains posts by him and you.
Yep I had a look LB as you suggested so thanks for that. This thread is nearly up to the same number of pages and as I suspected it has the same stuff stated over and over again. What I didn't find however as you asserted was the APS online course so I suppose its a case of:

Could you now review all your other posts in light of your apparently new-found ability to comprehend that you make mistakes?
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Old 13th Apr 2018, 10:22
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You should try to keep your prejudice sufficiently in check so as to not lie. What I said was:
The online content has been presented on PPRuNe and Andrew doesn’t accept it.
The content.

You’re a liar. I’m happy for you to take me on for defamation.
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Old 13th Apr 2018, 10:58
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In anticipation of my earlier post being deleted by the mods on the basis of whining from some poor pet...

Lookleft

I said this:
The online content has been presented on PPRuNe and Andrew doesn’t accept it.
You said this:
Yep I had a look [at the linked thread] LB as you suggested so thanks for that. This thread is nearly up to the same number of pages and as I suspected it has the same stuff stated over and over again. What I didn't find however as you asserted was the APS online course so I suppose its case of
I didn’t say the online course was in that thread. What I said was the content has been presented on PPRuNe.

I’d invite you to reconsider what you said, and correct it, if you can get past your blind prejudice.

Heck, you could even delete yours and I’ll delete mine.
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Old 13th Apr 2018, 11:05
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Originally Posted by Bend alot View Post
Sorry have not read all posts and not seen such a question.


22 BTDC would as more time to burn more fuel, the more fuel burnt in a sealed chamber has more energy, thus more HP.


Since the piston in a cylinder moves a greater distance in the first 90 degrees of rotation of the crank shaft than the second 90 degrees, it is desirable to have as much fuel as possible burnt in the cylinder at 0.000001 degrees after TDC.


Sea-level you refer is not just the pressure @ 16,000 feet temp will play a large factor - https://en.wikipedia.org/wiki/Standard_sea_level


Using a "pressure" only and insisting it is Sea Level is - well wrong!
Now I get it. You’re a comedian!

“it is desirable to have as much fuel as possible burnt in the cylinder at 0.000001 degrees after TDC.”

That’s genuinely hilarious. Comedy gold!
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Old 13th Apr 2018, 11:13
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LBLet's get that flame front moving a little before TDC so that the force is with you all the way down.
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Old 13th Apr 2018, 11:16
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Originally Posted by Lead Balloon View Post
Now I get it. You’re a comedian!

“it is desirable to have as much fuel as possible burnt in the cylinder at 0.000001 degrees after TDC.”

That’s genuinely hilarious. Comedy gold!


That is why the spark is before TDC.
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