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Discussion Starter #1 (Edited)
I wanted to read-up on the subject of firing order on v8 engines and found some interesting material on Wiki:

Firing order - Wikipedia, the free encyclopedia

I didn't realize cross-plane v8's were in the odd-fire category. The odd-fire/burbly sound explanation does make sense, though. That's one reason we all here like v8 sound, right?

So after reading the article, I still don't have much of an answer to my original curiosity...do Dodge, Chevy, Ford v8's all have the same firing pattern, or are there slight differences that ultimately contribute to unique sound signatures (particularly at idle and low rpm operation, rather than all-out rpm blast-offs)? The reason I wonder about this is I always notice GM v8's have more burble than other cars. When I hear a Chevy truck go by or pull up, it's got a burble that I wish my car had more of. So where does it come from? Is it just a matter of exhaust manifold design or if there is a cross-over pipe or not?...or do they do some sort of secret sauce in the firing pattern?

*note I specifically use the term "firing pattern" rather than firing order, because naturally, different makers number their cylinders differently (even bank/odd bank vs sequential numbering on each bank), and hence the firing order will change with that. The firing *pattern* is the end result of a particular firing order with a particular cylinder order. The latter can be different between 2 engines, but the former may actually be identical between those 2 engines. Confused, yet? I am, too. That is why I bring the subject up here, in hopes some master gear-head can enlighten me about this? :D

Another interesting term to throw into this mess is here:

http://en.wikipedia.org/wiki/Big-bang_firing_order

...not exactly related to v8's, but it does give a hint as to the nature of the "Harley sound" of a v-twin. It's a very aggressive staccato to the sound, and both cylinders firing together every 720 deg, instead of distributed every 360 deg, does make a lot of sense as to how that sound comes about.
 

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I believe all V8 engines have the same firing order. 1,3,5,7 is the left bank, 2,4,6,8 is the right bank and the distributor rotates clockwise. 1,8,4,3,6,5,7,2 Left bank is the drivers side and the right bank is the passenger side.
 

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We have cut cams and changed wireing in the firing order for certain
combo used on spefic dedication race motors. Yes changes the sound some.
FlatTop
 

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Discussion Starter #6
Very good point in that Hot Rod article about the significance of the cam in all of this. Can't just switch up your ignition wires and expect that could possibly work! ;)
 

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I believe all V8 engines have the same firing order. 1,3,5,7 is the left bank, 2,4,6,8 is the right bank and the distributor rotates clockwise. 1,8,4,3,6,5,7,2 Left bank is the drivers side and the right bank is the passenger side.
Fords are different where they number the cylinders 1234 on pass. side and 5678 on drivers side. Dist. rotation also differs on different engines and dist. location.
 

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Fords are different where they number the cylinders 1234 on pass. side and 5678 on drivers side. Dist. rotation also differs on different engines and dist. location.
My bad, you are absolutely correct - the cylinders in Ford engines are numbered as you noted and depending on engine and application the have different firing orders like 1-5-4-2-6-3-7-8 and 1-3-7-2-6-5-4-8.
 

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GM's LS and new LT engines have different firing order than Hemis: 1-8-7-2-6-5-4-3 versus 1-8-4-3-6-5-7-2 for our Hemis.

Cylinder numbering is the same, 1-3-5-7 on driver's side.
 

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Discussion Starter #12
So the missing piece of info to that is do they have the same cylinder numbering or is that different, too?
 

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Discussion Starter #14
So this is what we are looking at, correct?

Code:
 2-4-6-8
1-3-5-7
LS/LT: 1-8-7-2-6-5-4-3

Hemi: 1-8-4-3-6-5-7-2
 

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Discussion Starter #15 (Edited)
To pay homage to the wonderful CG work in Gravity, I present to you, below...my "puff map" simulation using ASCII characters! :grinbiginvert:

Code:
LS/LT

     **  *    *

 2-4-6-8
1-3-5-7

*  *   **   *
Code:
Hemi
         *
  *      *    *

 2-4-6-8
1-3-5-7

*      **
       **
What's it about?...I went through the firing order step-by step, introducing a * as a puff of smoke ejected to the exhaust manifold when that cylinder fires. Then I move all the puffs to the right one step to simulate the passage of time of 90 deg of crank angle. Then the new cylinder fires, introducing another * at the location of that cylinder. Then repeat through the entire sequence with a global step to the right each time, until I wrap back around to cylinder 1 firing. That is what I got!...pretty sure it is right, but who knows? I'm one tumbler into my usual evening fresher of vodka. :p

Here is the interesting bit...the GM v8 sequence seems rigged for mild distribution with some pulses lining up adjacent with another pulse as they travel to the right and similar series of "non-pulses" lining up adjacently. The Hemi v8 is significantly different with a distinct "pile-up" in pulses, not just in adjacent steps, but actually on top of one another, and similarly wide areas of "non-pulses".

...maybe not the most elaborate analysis you can apply to firing pattern and exhaust simulation, but a very interesting look at basic behavior, I think. ;)
 

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Discussion Starter #16
Now for kicks, I apply the same simulation to the Pentastar v6:

Code:
Pentastar v6
      *
      *
*     *

1-3-5
 2-4-6

      *
      *
      *
That's one, I didn't expect! This is using the following info I picked up:

"Called the Pentastar, its firing order of 1-2-3-4-5-6 is based on numbering the left bank (driver’s side) 2-4-6 and the passenger’s side 1-3-5."

MOTOR Magazine Article | MOTOR Information Systems
 

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I see what you're getting at with the piling up of the pressure waves in each exhaust manifold, and it stands to reason that this would give an irregular tone in the hemi and a more evenly distributed tone to the LS exhaust. Wouldn't this almost lead you to believe that a set of headers would have a greater impact on the performance of the Hemi due to the fact that the waves would have more room and not interfere with each other as much?
But then the question of the pentastar. Just to change it I tried 145236 and it still lines up as 3 deep. The fourth cylinder in the V8 is what gives the possibility of lower pressures at certain points.

Or as some are wondering I'm sure (Do they even know what the H are they talking about) LOL. :no:
 

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Discussion Starter #18 (Edited)
Yes, thank you for indulging me. I don't know if any of it means anything, either, but it looks "interesting", eh?

From those puff maps, it seems the Hemi should be more choppy and burbly than the GM, which is counter to my real life observations...then again, my observations have been of GM trucks. So maybe I need to explore if the firing pattern is any different on the Vortec v8's?

...so this is what I dig up for a GM Vortec firing order (same cylinder numbering pattern):

1-8-4-3-6-5-7-2

Comparing now to pre-established info:

LS/LT: 1-8-7-2-6-5-4-3

Hemi: 1-8-4-3-6-5-7-2

There it is!...our Hemi and the GM Vortec are a match for firing pattern. Who woulda thunk! (So if they don't have a similar sound from that aspect, it must be something else to it)
 

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Discussion Starter #19 (Edited)
So you know this one has to come up inevitably:

Ford 5.0L Coyote: 1-5-4-8-6-3-7-2

...and I believe they are the one to use a different cylinder numbering:

Code:
 5-6-7-8
1-2-3-4
Is that correct?

Here's how that works out:

Code:
Coyote v8:

       *
       **   *

 5-6-7-8
1-2-3-4

*  *   **   *
Code:
LS/LT

     **  *    *

 2-4-6-8
1-3-5-7

*  *   **   *
Code:
Hemi
         *
  *      *    *

 2-4-6-8
1-3-5-7

*      **
       **
 

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Did you read the article that CUDA put up in post 2, it references the fact that there will be much lower cylinder pressures when two cylinders fire next to each other in the order rather than from farther apart on the intake. The other thing I wonder about is that they run the exhaust pipes together to make the tones affect each other without combining the exhaust gasses, I don't know if that's to improve the sound or cancel it to quiet the output.

A quick test of the coyote order shows it to be pretty erratic as well as having areas with no pulses at all. (if I did it right)
 
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