How many crank revolutions to fire all cylinders?

Allan

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I understand how a CPC V8 works. Fire a cylinder for every 90 degrees of crank rotation. 90 degrees x 8 cylinders = 720 degrees. How does the voodoo work?





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To get a complete 4-stroke cycle (intake, compression, power, exhaust) for all cylinders, it takes 2 total crank revolutions.

Firing order, crank configuration, and cylinder count are irrelevant.

The voodoo still fires at 90* intervals like the coyote. The difference is that it never fires a cylinder on the same side twice, and always alternates banks.
 

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I understand how a CPC V8 works. Fire a cylinder for every 90 degrees of crank rotation. 90 degrees x 8 cylinders = 720 degrees. How does the voodoo work?
The same. The firing order alternates between banks but there's still a firing every 90 degrees.
 

JAJ

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Firing 2 cylinders at once?
No, just one at a time. I thought the word "alternately" would convey the "the right side then the left side then the right side and then the left side then the..." concept. Apparently not... :)

In a four-stroke V8 engine, all cylinders fire once every two revolutions regardless of whether it's CPC or FPC. On each revolution of the engine, four cylinders are firing and the four that aren't are pushing out exhaust and sucking in clean air and fuel, getting ready to fire on the next revolution.

The Ford Coyote CPC firing order is 1-5-4-8-6-3-7-2 which is L-R-L-R-R-L-R-L. Cylinders 1, 5, 4 and 8 fire on the first revolution, and 6, 3, 7 and 2 on the second revolution.

Once every revolution in the CPC engine, one bank of cylinders fires twice in a row. On the first revolution, cylinder 1 immediately follows 2 and on the second revolution cylinder 6 immediately follows 8.

The Voodoo FPC firing order is 1-5-4-8-3-7-2-6 which is L-R-L-R-L-R-L-R.

As you can see, it doesn't matter which bank fires, the next firing is always on the other bank.

How's that?
 
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No, just one at a time. I thought the word "alternately" would convey the "the right side then the left side then the right side and then the left side then the..." concept. Apparently not... :)

In a four-stroke V8 engine, all cylinders fire once every two revolutions regardless of whether it's CPC or FPC. On each revolution of the engine, four cylinders are firing and the four that aren't are pushing out exhaust and sucking in clean air and fuel, getting ready to fire on the next revolution.

The Ford Coyote CPC firing order is 1-5-4-8-6-3-7-2 which is L-R-L-R-R-L-R-L. Cylinders 1, 5, 4 and 8 fire on the first revolution, and 6, 3, 7 and 2 on the second revolution.

Once every revolution in the CPC engine, one bank of cylinders fires twice in a row. On the first revolution, cylinder 1 immediately follows 2 and on the second revolution cylinder 6 immediately follows 8.

The Voodoo FPC firing order is 1-5-4-8-3-7-2-6 which is L-R-L-R-L-R-L-R.

As you can see, it doesn't matter which bank fires, the next firing is always on the other bank.

How's that?
I appreciate your feed back. Maybe it’s because of to many shot to the head over the years but I’m still not grasping the math. 720 degrees of crank rotation. 8 cylinders. 180 degree crank. Enlighten me. What am I missing?
 
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I appreciate your feed back. Maybe it’s because of to many shot to the head over the years but I’m still not grasping the math. 720 degrees of crank rotation. 8 cylinders. 180 degree crank. Enlighten me. What am I missing?
Dumb ass engineers need the math.
 

RichGT350R

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every 180 degrees one cylinder fires. 180x8=1440 degrees. So that would be 1440/8 =8 so the 720 was wrong. That being said, how many rotations would be (4), (8) cylinders (1) every 1/2 rotation.
 
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Your math tells me your firing 2 cylinders at once. That is my confusion
Never mind me. I just watched a bunch of YouTube videos. It’s the mechanical design of the crank assembly that allows it to fire every 90 degrees of crank rotation. Thanks for the reply’s. Sorry I’m so dense.
 
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every 180 degrees one cylinder fires. 180x8=1440 degrees. So that would be 1440/8 =8 so the 720 was wrong. That being said, how many rotations would be (4), (8) cylinders (1) every 1/2 rotation.
Now your really meeting with me. Is it 720 or 1440?
 

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