Systems question for my exam on Monday
 

Hi all wonder if I could get some opinions please. I am going through some feedback for my systems on Monday and the following question has me wondering......

After the power stroke on a piston engine the poppet valve sequence is ?

A Exhaust open, inlet valvue open, exhaust valve close
C inlet valve opens, exhaust valve closes, inlet valve closes

answer says: A

Now if you think about theoretical otto cycle A is correct, but with the practical cycle as the exhaust valve opens before BDC of the power stroke the next lot of sequencing is option C.

so my question I suppose is, when does the power stroke end ? when it reaches BDC or when the exhaust valve is opens ?

I can't clearly find in my notes if the exhaust valve opening is part of power stroke or after power stroke.

Thanks in advance for any help

This looks like classic JAA. An ill-thought-out question is open to misinterpretation. Intelligent student thinks about it too much, and come up with the absolute right answer to the actual question, instead of the answer to the question the examiner was trying to write. I suspect the JAA answer is A, for is it not written "... thou art so sharp thee will cut theeself ...".

Good luck

Send Clowns
Nav/Flt Plng, BCFT

Dont forget order of bootstrap system.

Pamelas C**T Smells terrible

Best of luck

Since the Exhaust valve opens during the Power stroke (tdc to bdc the stroke is still 180 degrees whether theory or practical) then the answer is C.

They are testing you're knowledge of which stroke the exhaust valve opens on. The question says After the power stroke.