Some SBC theory
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From: All humans are vermin in the eyes of Guru VA
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Some SBC theory
OK so we have this 4 stroke engine. with 8 cylinders, I would assume that at any given time there are 2 cylinders in any given stroke.
Is this a correct assumption?
Is this a correct assumption?
Burning Brakes
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Originally Posted by Guru_4_hire
OK so we have this 4 stroke engine. with 8 cylinders, I would assume that at any given time there are 2 cylinders in any given stroke.
Is this a correct assumption?
Is this a correct assumption?
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From: All humans are vermin in the eyes of Guru VA
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Originally Posted by danthony
Actually all will be in some portion of stroke.
At any given time are 2 cylinders filling with air/fuel?
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From: All humans are vermin in the eyes of Guru VA
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Firing is an instant event.
Drawing in air is at least 180 degrees out of 720 degrees.
just because 2 cylinders are 90 degrees from one another doesnt mean that 2 cylinders arent filling.
Drawing in air is at least 180 degrees out of 720 degrees.
just because 2 cylinders are 90 degrees from one another doesnt mean that 2 cylinders arent filling.
Drifting
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answer, kinda
Guru,
A "stroke" is the travel of a piston (and rod) that goes from one end of the cylinder to the other, and that turns the crank 180 degrees, or half a complete cycle. For a piston to go from the top down to the bottom and up to the top again, it must make two strokes, one up, one down. The crank makes a complete 360 degree or full cycle.
Therefore, a four stroke engine must make the crankshaft turn 2x360 or 720 degrees for a full cycle. You then divide 720 by the number of cylinders in the engine to find the frequency of firing.
No two cylinders fire at once. With an eight cylinder engine, a cylinder fires every 90 degrees. (720/8 = 90). The more cylinders you have, the fewer number of degrees between firings and the smoother the engine, vibration wise.
Hope this helps.
Regards from Down Under
aussiejohn
A "stroke" is the travel of a piston (and rod) that goes from one end of the cylinder to the other, and that turns the crank 180 degrees, or half a complete cycle. For a piston to go from the top down to the bottom and up to the top again, it must make two strokes, one up, one down. The crank makes a complete 360 degree or full cycle.
Therefore, a four stroke engine must make the crankshaft turn 2x360 or 720 degrees for a full cycle. You then divide 720 by the number of cylinders in the engine to find the frequency of firing.
No two cylinders fire at once. With an eight cylinder engine, a cylinder fires every 90 degrees. (720/8 = 90). The more cylinders you have, the fewer number of degrees between firings and the smoother the engine, vibration wise.
Hope this helps.
Regards from Down Under
aussiejohn
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lets see...
360 degrees
2 revolutions per cycle so 4 pistons fire every 360 degrees.
360 / 4 = 90 degrees.
the intake stroke is 180 degrees.
therefore there are always two clyinders on the intake stroke?
360 degrees
2 revolutions per cycle so 4 pistons fire every 360 degrees.
360 / 4 = 90 degrees.
the intake stroke is 180 degrees.
therefore there are always two clyinders on the intake stroke?
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Melting Slicks
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Originally Posted by Guru_4_hire
Firing is an instant event.
Drawing in air is at least 180 degrees out of 720 degrees.
just because 2 cylinders are 90 degrees from one another doesnt mean that 2 cylinders arent filling.
Drawing in air is at least 180 degrees out of 720 degrees.
just because 2 cylinders are 90 degrees from one another doesnt mean that 2 cylinders arent filling.
Racer
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From: Winnipeg Manitoba
Originally Posted by Guru_4_hire
OK so we have this 4 stroke engine. with 8 cylinders, I would assume that at any given time there are 2 cylinders in any given stroke.
Is this a correct assumption?
Is this a correct assumption?
Yes this is a correct assumption.
However, they are not at the same point in the stroke.
That would mean they would fire at the same time.
If two cylinders are on the intake stroke,
one must be just finishing, and the other just starting.
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From: All humans are vermin in the eyes of Guru VA
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Originally Posted by aussiejohn
Guru,
A "stroke" is the travel of a piston (and rod) that goes from one end of the cylinder to the other, and that turns the crank 180 degrees, or half a complete cycle. For a piston to go from the top down to the bottom and up to the top again, it must make two strokes, one up, one down. The crank makes a complete 360 degree or full cycle.
Therefore, a four stroke engine must make the crankshaft turn 2x360 or 720 degrees for a full cycle. You then divide 720 by the number of cylinders in the engine to find the frequency of firing.
No two cylinders fire at once. With an eight cylinder engine, a cylinder fires every 90 degrees. (720/8 = 90). The more cylinders you have, the fewer number of degrees between firings and the smoother the engine, vibration wise.
Hope this helps.
Regards from Down Under
aussiejohn
A "stroke" is the travel of a piston (and rod) that goes from one end of the cylinder to the other, and that turns the crank 180 degrees, or half a complete cycle. For a piston to go from the top down to the bottom and up to the top again, it must make two strokes, one up, one down. The crank makes a complete 360 degree or full cycle.
Therefore, a four stroke engine must make the crankshaft turn 2x360 or 720 degrees for a full cycle. You then divide 720 by the number of cylinders in the engine to find the frequency of firing.
No two cylinders fire at once. With an eight cylinder engine, a cylinder fires every 90 degrees. (720/8 = 90). The more cylinders you have, the fewer number of degrees between firings and the smoother the engine, vibration wise.
Hope this helps.
Regards from Down Under
aussiejohn
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From: All humans are vermin in the eyes of Guru VA
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Originally Posted by Kilroy1024
Yes this is a correct assumption.
However, they are not at the same point in the stroke.
That would mean they would fire at the same time.
If two cylinders are on the intake stroke,
one must be just finishing, and the other just starting.
However, they are not at the same point in the stroke.
That would mean they would fire at the same time.
If two cylinders are on the intake stroke,
one must be just finishing, and the other just starting.
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From: All humans are vermin in the eyes of Guru VA
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Originally Posted by 427V8
lets see...
360 degrees
2 revolutions per cycle so 4 pistons fire every 360 degrees.
360 / 4 = 90 degrees.
the intake stroke is 180 degrees.
therefore there are always two clyinders on the intake stroke?
360 degrees
2 revolutions per cycle so 4 pistons fire every 360 degrees.
360 / 4 = 90 degrees.
the intake stroke is 180 degrees.
therefore there are always two clyinders on the intake stroke?
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From: All humans are vermin in the eyes of Guru VA
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Originally Posted by shafrs3
I knew I could get you to answer your own question. You really didn't need an answer did you, just someone to have an intellectual sparing match with, right?
Burning Brakes
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Originally Posted by Kilroy1024
Yes this is a correct assumption.
However, they are not at the same point in the stroke.
That would mean they would fire at the same time.
If two cylinders are on the intake stroke,
one must be just finishing, and the other just starting.
However, they are not at the same point in the stroke.
That would mean they would fire at the same time.
If two cylinders are on the intake stroke,
one must be just finishing, and the other just starting.
1-8-4-3-6-5-7-2.
Melting Slicks
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From: Austin TX
Actually, SBC bought AT&T,..but we digress.
Look down at the distributor cap and know that the rotor turns half as fast as the crank,..maybe that will offer some understanding,..(or confuse you further). So when the rotor fires off the one cylinder, then makes a full revolution, and fires it off again, the crank has turned twice, allowing the one piston to cycle through it's four strokes. One stroke = half a rotation of the crank (as stated earlier, the four strokes are combustion, exhaust, intake, and compression).
Notice that the one post on the distr. cap is directly opposite the six post,..so while the one cylinder is firing (beginning the combusiton stroke) the 6 cylinder is beginning it's intake stroke.
Look down at the distributor cap and know that the rotor turns half as fast as the crank,..maybe that will offer some understanding,..(or confuse you further). So when the rotor fires off the one cylinder, then makes a full revolution, and fires it off again, the crank has turned twice, allowing the one piston to cycle through it's four strokes. One stroke = half a rotation of the crank (as stated earlier, the four strokes are combustion, exhaust, intake, and compression).
Notice that the one post on the distr. cap is directly opposite the six post,..so while the one cylinder is firing (beginning the combusiton stroke) the 6 cylinder is beginning it's intake stroke.
Instructor
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From: Wallaceburg Ontario
Could you imagine how rough a V8 would run if two cylinders fired at the EXACT same time? Or would it just run like a huge four banger (25% is 25% no matter how you cut it)? Someone once told me that there was a group in Europe who experimented with a V8 that had two cylinders firing at the exact same time. Apparently, it was a huge failure.