Firing order and exhaust note... - Team Camaro Tech
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post #1 of 29 (permalink) Old Jan 14th, 09, 05:41 AM Thread Starter
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Firing order and exhaust note...

What's the physical difference in firing order between the Mustang and the Chevy that would cause the difference in exhaust sound?

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post #2 of 29 (permalink) Old Jan 14th, 09, 07:11 AM
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Re: I have a General question about cylinder heads.

The timing of the sound pulses and, of course, exhaust system and internal muffler design, i.e., sound chamber design, Helmholz(?) design. Unless I'm in left field, Professor?

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post #3 of 29 (permalink) Old Jan 14th, 09, 08:55 AM Thread Starter
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Re: I have a General question about cylinder heads.

I would agree that the exhaust system design tailors the sound, as well as the cam timing, etc., my question was in regards to the firing order proper. It seems to me that the sound pulses emit from the engine in the same order and timing from a 5.0 Mustang as they do from an SBC, basically a RLLRLRRL sequence.

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post #4 of 29 (permalink) Old Jan 14th, 09, 10:09 AM
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Re: I have a General question about cylinder heads.

Ford's 5.0 Liter firing order
LLRLRRLR - 13726548

Chevrolet 5.0 liter firing order
LLRLRRLR - 8436572(1) moved for clarity.

Still thinking............

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post #5 of 29 (permalink) Old Jan 14th, 09, 12:16 PM
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Thumbs up Re: I have a General question about cylinder heads.

Quote:
Originally Posted by Everett#2390 View Post
... Still thinking............
It's a tough one to get your head around
But, if you've ever heard one of those older experimental "180deg"* SBC's barking through a set of headers as it made a pass you'll never forget how just changing the firing order can radically change the exhaust note.

* = not sure if anyone still does this or not, it was 'sorta' popular with several engine builders in the 70's. It phased the cyclinders to fire in the order they are at 180 to each othe, rather than the slightly out-of-phase sequence GM engineered - "supposed" to add a small amount of HP at top end... my one try with it was a bust - but a cam grinder made some money.

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Last edited by Vintage 68; Jan 14th, 09 at 12:31 PM.
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post #6 of 29 (permalink) Old Jan 14th, 09, 12:29 PM
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Re: I have a General question about cylinder heads.

While the firing order is different between chevy and ford, don't they also number thier cylinders differently?

Chevy Ford
Engine Front
1 2 1 5
3 4 2 6
5 6 3 7
7 8 4 8

I thought I read somewhere that on the new vette's the firing order changed to reduce crank loading (4/7 swap), but ends up firing the cylinders in the same sequence as ford if you number the cylinders the same.
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post #7 of 29 (permalink) Old Jan 14th, 09, 12:40 PM
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Re: I have a General question about cylinder heads.

Quote:
Originally Posted by Vintage 68 View Post
It's a tough one to get your head around
But, if you've ever heard one of those older experimental "180deg"* SBC's barking through a set of headers as it made a pass you'll never forget how just changing the firing order can radically change the exhaust note.

* = not sure if anyone still does this or not, it was 'sorta' popular with several engine builders in the 70's. It phased the cyclinders to fire in the order they are at 180 to each othe, rather than the slightly out-of-phase sequence GM engineered - "supposed" to add a small amount of HP at top end... my one try with it was a bust - but a cam grinder made some money.
Agreed, I remember 180 exhaust headers being used by the roundy-round boys and definately made a different sound - sweeter sounding.

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post #8 of 29 (permalink) Old Jan 14th, 09, 12:43 PM
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Re: I have a General question about cylinder heads.

Quote:
Originally Posted by freezined View Post
While the firing order is different between chevy and ford, don't they also number thier cylinders differently?

Chevy Ford
Engine Front
1 2 1 5
3 4 2 6
5 6 3 7
7 8 4 8

I thought I read somewhere that on the new vette's the firing order changed to reduce crank loading (4/7 swap), but ends up firing the cylinders in the same sequence as ford if you number the cylinders the same.
Yes, Ford does number different, but Ford has #1 on Pass side front.
Ford -front
5 1
6 2
7 3
8 4

But as shown by my earlier post, "Still thinkin'" I've taken GM #1 cyl and placed it after #2 (see the firing order?) and the result is the same = both are a match.

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post #9 of 29 (permalink) Old Jan 14th, 09, 02:36 PM
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Re: I have a General question about cylinder heads.

Quote:
Originally Posted by Everett#2390 View Post
Ford's 5.0 Liter firing order
LLRLRRLR - 13726548

Chevrolet 5.0 liter firing order
LLRLRRLR - 8436572(1) moved for clarity.

Still thinking............
If that Ford firing order is correct, there's 3 odd numbered cylinders firing in a row instead of 2.

Mark

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post #10 of 29 (permalink) Old Jan 14th, 09, 02:50 PM Thread Starter
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Re: I have a General question about cylinder heads.

Quote:
Originally Posted by mbrekke View Post
If that Ford firing order is correct, there's 3 odd numbered cylinders firing in a row instead of 2.

Mark
Ford has 1 to 4 on one bank and 5 to 8 on the other. Chevy has the odd numbers on one side and the even numbers on the other.

"For those that will fight for it...FREEDOM ...has a flavor the protected shall never know."
Semper Fi! L/Cpl Edwin L. "Tim" Craft, B Co 3rd AT's, Khe Sanh Combat Base, February, 1968
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post #11 of 29 (permalink) Old Jan 14th, 09, 03:19 PM
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Re: I have a General question about cylinder heads.

Quote:
Originally Posted by onovakind67 View Post
Ford has 1 to 4 on one bank and 5 to 8 on the other. Chevy has the odd numbers on one side and the even numbers on the other.
Well cut my legs and call me shorty. How dumb is that? I've worked on lots of Ford six bangers, but not V-8's... obviously.

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post #12 of 29 (permalink) Old Jan 14th, 09, 05:04 PM
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Re: Firing order and exhaust note...

I have thought about this today as I drove my tractor around. Just a couple of things to consider.

Personally, at the dragstrips with cars with no mufflers, I have often thought I noticed a difference in the sound of chevy and ford engines of somewhat comparable size and power. I have tried to convince myself that this difference I am noticing is purely anecdotal. Maybe it is anecdotal, maybe not. Like most here I am a bowtie fan and thus I am biased.

I will list the firing of each engine to see if there is a pattern. But first we need to renumber the cylinders so that we are comparing apples to apples.

For simplicity I will use the sbc/bbc pattern to label the cylinders in both engines, which willindicate numbers 1-3-5-7 on the driver side, and 2-4-6-8 on the opposite side. So forget about the order that Ford used to number their cylinders. The factory numbers are just for identification. What we are after,imo, is if there is a difference in the firing of consecutive cylinders in each bank. AND THERE IS!!

I will use 8 revolutions for each engine as an illustration (2880* cranktrain revolution total), which means there will be 4 fires in each cylinder for this experiment.There is 90* of cranktrain revolution per fire. I will start with cylinder number 1, which is identified the same by both companies (8 is the only other cylinder that fires in the same actual order for the trivia buffs)

Chevy LRRLRLLRLRRLRLLRLRRLRLLRLRRLRLLRLRRLRLLRLRRLRLLRLR RLRLLRLRRLRLLR

Ford LLLRRLRRLLLRRLRRLLLRRLRRLLLRRLRRLLLRRLRRLLLRRLRRLL LRRLRRLLLRRLRR

We see that the driver's side bank fires three consecutive times in the Ford in 720* of cranktrain rotation. The Chevy never does this. The right bank of the Ford has 2 cylinders that fire consecutively twice in each 720* of cranktrain rotation, the Chevy fires a single cylinder in the right bank twice per 720*, and fires 2 consecutive cylinders in the right bank once per 720*.

If there is actually a difference in the sound of the exhaust in these engines, this is the likely cause of the difference. And I think Occam would approve

This was quite a mind bending effort. I think it is only fair as compensation for such effort that someone rewards me with a numbers matching '69 pace car in immaculate condition .

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Last edited by Eleanor's Nemesis; Jan 14th, 09 at 05:18 PM. Reason: grammar correction
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post #13 of 29 (permalink) Old Jan 14th, 09, 05:23 PM
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Thumbs up Re: Firing order and exhaust note...

Quote:
Originally Posted by Eleanor's Nemesis View Post
I have thought about this today as I drove my tractor around. ...

Chevy LRRLRLLRLRRLRLLRLRRLRLLRLRRLRLLRLRRLRLLRLRRLRLLRLR RLRLLRLRRLRLLR

Ford LLLRRLRRLLLRRLRRLLLRRLRRLLLRRLRRLLLRRLRRLLLRRLRRLL LRRLRRLLLRRLRR

If there is actually a difference in the sound of the exhaust in these engines, this is likely the difference.

This was quite a mind bending effort. I think it is only fair as compensation for such effort that someone rewards me with a numbers matching '69 pace car in immaculate condition .
So, now close you eyes and ponder what a SBC that fires LRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLR LRLR ... sounds like
That's why those old "180's" sounded so weird

You need to pay the taxes and a 'handling charge' on the 69-pacer you've won - so just send me a Western Union money transfer for $120,000 and I'll see that you car is released from the prize vault and shipped directly to you - we don't need your address, it's on file

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Last edited by Vintage 68; Jan 14th, 09 at 11:01 PM. Reason: spellin - as always ...
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post #14 of 29 (permalink) Old Jan 14th, 09, 05:30 PM
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Re: Firing order and exhaust note...

Quote:
Originally Posted by Vintage 68 View Post
So, now close you eyes and ponder what a SBC the fires LRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLRLR LRLR ... sounds like
That's why those old "180's" sounded so weird

You need to pay the taxes and a 'handling charge' on the 69-pacer you've won - so just send me a Western Union money transfer for $120,000 and I'll see that you car is released from the prize vault and shipped directly to you - we don't need your address, it's on file
Oh, we do this deal overseas...no taxes, and cheap labor for the handling fees And I won't complain if it is a small block.

just to eliminate any confusion, I referred to the drivers side as L and the passenger side as R.

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1968 Street/Strip Camaro 350 w/PG
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post #15 of 29 (permalink) Old Jan 14th, 09, 05:42 PM
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Quote:
Originally Posted by Eleanor's Nemesis View Post
... just to eliminate any confusion, I referred to the drivers side as L and the passenger side as R.
As does anyone who knows anything vehicles

I'll talk to my broker and see if he can just send you a check for $250,000 - you buy a duplicate 69 and ship it to him and you can keep the rest after you cash it

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