Engineering Would the two stroke spark ignition PV digram be same as for a 4 stroke?

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The discussion centers on the differences between the PV diagrams of two-stroke and four-stroke spark ignition engines. Both types utilize Otto PV diagrams, but the two-stroke engine combines the intake and exhaust phases into the compression stroke, resulting in only four key points on its diagram. In contrast, the four-stroke engine has distinct intake and exhaust strokes, leading to a total of four identifiable strokes in its PV diagram. Participants clarify the phases of each engine type, emphasizing that the intake and exhaust phases are not separately represented in the two-stroke diagram. This distinction highlights the fundamental operational differences between the two engine designs.
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Homework Statement
write about engines
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Would two stroke spark ignition PV digram be same as 4 stroke spark ignition. both have otto pv diagrams.

1623567900237.png
 
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What research have you done on this so far?
 
Chestermiller said:
What research have you done on this so far?
ive write about everything just getting confused on the PV diagrams pics to put into the document. i think its otto pv diagram.
 
How many strokes can you identify on the diagram in the OP?
 
jack action said:
How many strokes can you identify on the diagram in the OP?
I was thinking on the diagram
stages 1 -2 - 3 compression and 3 -4 - 1 was expansion
 
A stroke is a displacement ##V_s##. From 2 to 3 and 4 to 5, there are no displacements (constant volume), so let's forget about those for the moment. But you are correct with 1-2 for compression and 3-4 for expansion. But what about 0-1 and 5-0?
 
jack action said:
A stroke is a displacement ##V_s##. From 2 to 3 and 4 to 5, there are no displacements (constant volume), so let's forget about those for the moment. But you are correct with 1-2 for compression and 3-4 for expansion. But what about 0-1 and 5-0?
would 2 -3 be ignition phase and 4 - 5 would heat rejection?

0 - 1 Intake Stroke?
5 - 0 Exhaust Stroke?
 
2-3 would be combustion and 4-5 would be heat rejection (or cooling), but that doesn't have anything to do with our strokes.
lee123456789 said:
0 - 1 Intake Stroke?
5 - 0 Exhaust Stroke?
So now you have identified a total of 4 strokes. I guess this is good for a 4-stroke engine PV diagram.

How would a 2-stroke engine PV diagram differ?
 
jack action said:
2-3 would be combustion and 4-5 would be heat rejection (or cooling), but that doesn't have anything to do with our strokes.

So now you have identified a total of 4 strokes. I guess this is good for a 4-stroke engine PV diagram.

How would a 2-stroke engine PV diagram differ?
There would just be a compression stroke and expansion stroke and the exhaust would be in included in the compression stroke and intake would be included in compression stroke?
 
  • #10
lee123456789 said:
There would just be a compression stroke and expansion stroke and the exhaust would be in included in the compression stroke and intake would be included in compression stroke?
jack action said:
2-3 would be combustion and 4-5 would be heat rejection (or cooling), but that doesn't have anything to do with our strokes.

So now you have identified a total of 4 strokes. I guess this is good for a 4-stroke engine PV diagram.

How would a 2-stroke engine PV diagram differ?
I think this would be the sequence of 2 stroke

0 to 1 intake phase
1 to 2 compression stroke
2 to 3 ignition phase
3 to 4 expansion stroke
4 to 5 heat rejection phase
5 to 0 exhaust phase
 
  • #11
Post #9 is good, post #10 is wrong, or at least confusing. The intake phase (0-1) and exhaust phase (5-0) will not appear on the PV diagram as they will be included in the compression and expansion strokes. They are only 2 strokes.
 
  • #12
jack action said:
Post #9 is good, post #10 is wrong, or at least confusing. The intake phase (0-1) and exhaust phase (5-0) will not appear on the PV diagram as they will be included in the compression and expansion strokes. They are only 2 strokes.
I think this is it

0 to 1 to 2 to 3 compression stroke - included intake phase, compression stroke and ignition phase.

3 to 4 to 5 to 0 power stroke - includes power stroke, heat rejection, and exhaust phase
 
  • #13
There are no 0 to 1 nor 5 to 0 lines drawn on the PV diagram. That is the difference between the 2-stroke and the 4-stroke PV diagrams. The 2-stroke has only 4 points:

-assignment-help-with-two-stroke-engine-pv-diagram.jpg
Both the intake & exhaust phases will begin somewhere between 3 and 4 and end somewhere between 1 and 2.

Versus a 4-stroke engine PV diagram:

23ae3f3d-8f23-488a-b17e-f7f95ac1d435.jpg
 
  • #14
jack action said:
There are no 0 to 1 nor 5 to 0 lines drawn on the PV diagram. That is the difference between the 2-stroke and the 4-stroke PV diagrams. The 2-stroke has only 4 points:

Both the intake & exhaust phases will begin somewhere between 3 and 4 and end somewhere between 1 and 2.

Versus a 4-stroke engine PV diagram:

Sorry could u layout the strokes eg 1 to 2 to 3.
Sorry for being thick.1 to 2 to 3 I take, compression stroke and ignition.

3 to 4 to 1. Power stroke, heat rejection and exhaust.
 
  • #15
If you look at the 4-stroke engine PV diagram in my last post, a downward stroke is from TDC (top dead center) to BDC (bottom dead center) and an upward stroke is from BDC to TDC. The same limits applied to a 2-stroke engine.
 
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