AGK Question I got wrong - wise engine people needed
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AGK Question I got wrong - wise engine people needed
Engine running full rich, progressively leaning the mixture would produce?
a.a. Chemically correct first, best power, peak EGT
b.b. Best power first then peak EGT then chemically correct mixture
c.c. Peak EGT first then best power then chemically correct mixture
d.d. Best power first then chemically correct mixture then peak EGT.
Can you explain the answer to this one?
I think its D, as best power is slightly richer than chemically correct. And peak EGT would be the leanest setting?
The book i have doesn't have enough info on this.
It marked me incorrect, but ive had problems with the answers in the past. Anyone explain?
Thankyou!
a.a. Chemically correct first, best power, peak EGT
b.b. Best power first then peak EGT then chemically correct mixture
c.c. Peak EGT first then best power then chemically correct mixture
d.d. Best power first then chemically correct mixture then peak EGT.
Can you explain the answer to this one?
I think its D, as best power is slightly richer than chemically correct. And peak EGT would be the leanest setting?
The book i have doesn't have enough info on this.
It marked me incorrect, but ive had problems with the answers in the past. Anyone explain?
Thankyou!
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A
My answer would be 'A' ksa.
As far as i remember from piston knowledge, or lack of
, the chemically correct mixture is approximately 15-1 (air/fuel ratio) which is relatively 'rich', then as you lean the mixture from there you get to 'best power' shortly followed by 'peak EGT', which then leaned further you can get best economy at lower power settings.
Im probably not the right person to give you a more technical answer than that, and if anyone thinks i am wrong, please fell free to divulge a more correct answer.
Heads up champ, and keep studying, the answers are out there.
HTB
As far as i remember from piston knowledge, or lack of
, the chemically correct mixture is approximately 15-1 (air/fuel ratio) which is relatively 'rich', then as you lean the mixture from there you get to 'best power' shortly followed by 'peak EGT', which then leaned further you can get best economy at lower power settings.Im probably not the right person to give you a more technical answer than that, and if anyone thinks i am wrong, please fell free to divulge a more correct answer.
Heads up champ, and keep studying, the answers are out there.
HTB
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Thanks HireTheBetter, Contradicting information! 
The answer was infact B
But I do not understand why and the differences between CCM and / Peak EGT are.
I though Peak EGT would be leaner than CCM in general thinking.
Also another one for some more trivia!
Chances of spark plug lead failure due to arcing increase with?
The answer is pressure altitude
I got it correct, but I Couldn't find the answer in a text book.
I wish I bought bob tait's instead of these damn theory centre books.
The answer was infact B
But I do not understand why and the differences between CCM and / Peak EGT are.
I though Peak EGT would be leaner than CCM in general thinking.
Also another one for some more trivia!
Chances of spark plug lead failure due to arcing increase with?
The answer is pressure altitude
I got it correct, but I Couldn't find the answer in a text book.
I wish I bought bob tait's instead of these damn theory centre books.
Last edited by ksa5223; 4th Feb 2008 at 23:32.
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answer (a) is definitely incorrect.
ccm mixture provides the hottest, quickest burning flame in the cylinder and theoretically, peak EGT.
however, in practice, most EGT gauges are not accurate enough to determine ccm precisely. on most of the graphs i have seen, best economy mixture is defined as a band (peak EGT). ccm is in the middle of this band. you would therefore achieve this "peak EGT band" before you were truly at ccm while leaning from fully rich.
best power is richer than both peak EGT band and ccm and occurs at peak CHT (due to presence of lots of nitrogen in the air).
the answer therefore should be (b).
the tricky question is, if ccm mixture provides the hottest flame in the cylinder, why does a very lean detonating mixture produce a rise in CHT?
ccm mixture provides the hottest, quickest burning flame in the cylinder and theoretically, peak EGT.
however, in practice, most EGT gauges are not accurate enough to determine ccm precisely. on most of the graphs i have seen, best economy mixture is defined as a band (peak EGT). ccm is in the middle of this band. you would therefore achieve this "peak EGT band" before you were truly at ccm while leaning from fully rich.
best power is richer than both peak EGT band and ccm and occurs at peak CHT (due to presence of lots of nitrogen in the air).
the answer therefore should be (b).
the tricky question is, if ccm mixture provides the hottest flame in the cylinder, why does a very lean detonating mixture produce a rise in CHT?
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Ahhh I see!
I am going to leave this thread open, I am bound to run into more tricky ones.. Doing another practice test now
Thanks for the brain food links and the graphs there guys!
Anyone know about the electrical question a few posts uP^^?
I am going to leave this thread open, I am bound to run into more tricky ones.. Doing another practice test now
Thanks for the brain food links and the graphs there guys!
Anyone know about the electrical question a few posts uP^^?
