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Author Topic: Firing order/rpm question  (Read 1433 times)
Davemn
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Posts: 830

Minnetrista, Minnesota


« on: April 14, 2015, 02:24:33 PM »

How many plugs fire in 1 complete revolution? Are the pistons 60 degrees apart or 120 degrees apart or something else?
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BobB
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One dragon on the tail of another.


« Reply #1 on: April 14, 2015, 03:02:08 PM »

In the 720o of the four stroke cycle, each cylinder is firing for the power stroke 120o apart.  We have three coils providing the spark, one for cylinders 1 & 2, one for cylinders 3 & 4 and one for cylinders 5 & 6.  I believe the ignition order is 1, 4, 5, 2, 3 & 6.  Realize that the plugs actually fire at the end of the exhaust stroke as well as the compression stroke, 360o apart...
« Last Edit: April 14, 2015, 03:06:53 PM by BobB » Logged

pancho
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Bonanza Arkansas


« Reply #2 on: April 14, 2015, 03:10:06 PM »

Another way of looking at it is, in one motor revolution (360 degrees) three cylinders will fire, and the pistons/cylinders are spaced opposing at 180 degrees in our flat six motors.
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98valk
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South Jersey


« Reply #3 on: April 14, 2015, 03:18:49 PM »

it is a wasted spark ignition system, much written about it on web sites including some plugs work better than others.
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Cracker Jack
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« Reply #4 on: April 14, 2015, 05:19:55 PM »

If it's not already clear to you, let me add this. There are three sets of pistons, each set are at TDC at the same time, 120 degrees apart  First set ( 1&2) are first then 120 degrees later (4&5) then finally 120 degrees later (5&6). The first round, #1, 4 & 5 fire then the second round # 2, 3, & 6 fire.
Thus the firing order is 1, 4, 5, 2, 3, 6 . It takes two rounds to fire all six cylinders.

To answer your question, the three crankshaft pairs are 120 degrees apart and a power stroke occurs every 120 degrees, three per each crankshaft turn.

Cracker angel
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Chrisj CMA
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Crestview (Panhandle) Florida


« Reply #5 on: April 15, 2015, 08:34:14 AM »

Another way of looking at it is, in one motor revolution (360 degrees) three cylinders will fire, and the pistons/cylinders are spaced opposing at 180 degrees in our flat six motors.

3 fire for power the other 3 fire for fun at the same time then next rotation they switch places.....they all need to have fun!
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