how many firing sequences for 90* V-8

[USMC_Spike]

I found this interesting:


Regarding the Diamler Vee-Eight

Rt....Lt
4.....8
3.....7
2.....6
1.....5

The induction impulses on each carburetter are equal, as the order is 1-5-4-2-6-3-7-8,
numbered as (front to back) right bank 1-2-3-4 and left bank 5-6-7-8. It will be seen that
although a power stroke occurs at each 90 deg., (and an induction impulse at
each 180 deg. on one of the carburetters) there is uneven firing in each bank, which can be
shown as follows:

Right bank 1-42-3--
Left bank..-5--6-78

Smith, Philip H. (1967) The Design and Tuning of Competition Engines, 4th ed,
.....Robert Bentley, Cambridge, Massachusetts, USA....p241


The Standard Chevrolet BBC or SBC is shown as:

Rt...Lt
8.....7
6.....5
4.....3
2.....1

The firing order: 1-8-4-3-6-5-7-2.
The banks each fire as shown:

Right bank.-84-6--2
Left bank..1--3-57-

BMWs 2.6 Litre Vee-eight
Rt...Lt
4.....8
3.....7
2.....6
1.....5

Firing order: 1-5-4-8-6-3-7-2

Right bank 1-4--3-2
Left bank..-5-86-7-

(Smith, p424)

Put into Chevrolet That would look like:

Rt...Lt
8.....7
6.....5
4.....3
2.....1

The firing order: 2-1-8-7-3-6-5-4.
converted as: 1-8-7-3-6-5-4-2
The banks each fire as shown:

right bank. 2-8--6-4
Left bank..-1-73-5-

Laid out as shown, helps visualize the layout and what is happening (a little bit).
Especially for those of us who don't do this all the time.

Hope this helps.

Cheers,

Spike

[A Atwood]

In a 90* V8 with a standard crank, there are exactly 8 different firing order combinations. And no matter how you fire it, two cylinders on the same bank always fire back to back. There is also a 270* break on each bank.
In order to get away from this, the crank must be changed to a flat crank. They also have a completely different exhaust note.
With the standard crank, no matter what the firing order, the exhaust note is the same.
Personally, I love the standard crank "sound"

ARN

[MadBill]

"With the standard crank, no matter what the firing order, the exhaust note is the same."

-Unless you fire two at a time...

[robert1]

I found this interesting:


Regarding the Diamler Vee-Eight

Rt....Lt
4.....8
3.....7
2.....6
1.....5

The induction impulses on each carburetter are equal, as the order is 1-5-4-2-6-3-7-8,
numbered as (front to back) right bank 1-2-3-4 and left bank 5-6-7-8. It will be seen that
although a power stroke occurs at each 90 deg., (and an induction impulse at
each 180 deg. on one of the carburetters) there is uneven firing in each bank, which can be
shown as follows:

Right bank 1-42-3--
Left bank..-5--6-78

Smith, Philip H. (1967) The Design and Tuning of Competition Engines, 4th ed,
.....Robert Bentley, Cambridge, Massachusetts, USA....p241


The Standard Chevrolet BBC or SBC is shown as:

Rt...Lt
8.....7
6.....5
4.....3
2.....1

The firing order: 1-8-4-3-6-5-7-2.
The banks each fire as shown:

Right bank.-84-6--2
Left bank..1--3-57-

BMWs 2.6 Litre Vee-eight
Rt...Lt
4.....8
3.....7
2.....6
1.....5

Firing order: 1-5-4-8-6-3-7-2

Right bank 1-4--3-2
Left bank..-5-86-7-

(Smith, p424)

Put into Chevrolet That would look like:

Rt...Lt
8.....7
6.....5
4.....3
2.....1

The firing order: 2-1-8-7-3-6-5-4.
converted as: 1-8-7-3-6-5-4-2
The banks each fire as shown:

right bank. 2-8--6-4
Left bank..-1-73-5-

Laid out as shown, helps visualize the layout and what is happening (a little bit).
Especially for those of us who don't do this all the time.

Hope this helps.

Cheers,

Spike

These are the same as a Chevrolet if you number the cylinders the same. One is a standard firing order and the other is a 4/7 swap

[A Atwood]

"With the standard crank, no matter what the firing order, the exhaust note is the same."

-Unless you fire two at a time...

Alright, you got me.
Now that would make things interesting.
The sound would be extremely unique.
Each time a fire would occur, one cylinder on each bank would fire simultaneously.
But it would not be even at all.

Here's how it would go:
Two fire(one on each bank)
180* break
Two fire
90* break
Two fire
180* break
Two fire
270* break

It would have the sound of one bank of a V8 but double the amplitude.

I'd like to hear that!!

ARN

[DaveMcLain]

"With the standard crank, no matter what the firing order, the exhaust note is the same."

-Unless you fire two at a time...

On the older 4.6 Ford V8 engines it was possible to do this very easily by timing both of the cams so that the running mates were both in the firing position at the same time. I know a guy who works at a dealer that had a guy do that when he fixed a head gasket on one side of the engine. It sounded sort of weird but it did not run as bad as you'd think and if I remember right I don't think it even set a code/check engine light. Later when they stopped using the waste spark setup and went to coil on plug ignition this was no longer possible.

[dave brode]

snipped


With the standard crank, no matter what the firing order, the exhaust note is the same.

ARN

Then you feel that a 18436572 chev sounds the same as an LS / HO ford? They sound different to me, and I assumed that it was due to the firing sequence.

Dave

[A Atwood]

snipped


With the standard crank, no matter what the firing order, the exhaust note is the same.

ARN

Then you feel that a 18436572 chev sounds the same as an LS / HO ford? They sound different to me, and I assumed that it was due to the firing sequence.

Dave

The exhaust note is the same. Most all the difference you hear is the exhaust type (h-pipe, x-pipe, no pipe, etc. etc.) and rpm. I'm certain other factors will change the sound as well. Such as different power levels, header pipe diameter, collector diameter and length. The list goes on.
But it has NOTHING to do with the firing order.

Take any V8 engine, and change the firing order(with a cam of same spec, different firing order). If you don't change the exhaust, it will sound the same.


ARN

[lorax]

"With the standard crank, no matter what the firing order, the exhaust note is the same."

-Unless you fire two at a time...

Alright, you got me.
Now that would make things interesting.
The sound would be extremely unique.
Each time a fire would occur, one cylinder on each bank would fire simultaneously.
But it would not be even at all.

Here's how it would go:
Two fire(one on each bank)
180* break
Two fire
90* break
Two fire
180* break
Two fire
270* break

It would have the sound of one bank of a V8 but double the amplitude.

I'd like to hear that!!

ARN

I had a flat M/T cast nodular 3.25 crank for a SBF back in the mid 60s that I originally ran as a left/right crank with Hilborn stacks. It sounded like 2 ricer burners racing, not unlike a set of 180* headers, except it did it with standard 4 to 1 headers. But it never ran all that well. Changed the cam to fire 2 at a time using a modified Spaulding Flamethrower, The crank broke after about 30 runs. It didn't run any better, and thumped like a 500cc BSA single. Crank just couldn't take the double whammie of 2 cylinders firing at a time.

[A Atwood]

"With the standard crank, no matter what the firing order, the exhaust note is the same."

-Unless you fire two at a time...

Alright, you got me.
Now that would make things interesting.
The sound would be extremely unique.
Each time a fire would occur, one cylinder on each bank would fire simultaneously.
But it would not be even at all.

Here's how it would go:
Two fire(one on each bank)
180* break
Two fire
90* break
Two fire
180* break
Two fire
270* break

It would have the sound of one bank of a V8 but double the amplitude.

I'd like to hear that!!

ARN

I had a flat M/T cast nodular 3.25 crank for a SBF back in the mid 60s that I originally ran as a left/right crank with Hilborn stacks. It sounded like 2 ricer burners racing, not unlike a set of 180* headers, except it did it with standard 4 to 1 headers. But it never ran all that well. Changed the cam to fire 2 at a time using a modified Spaulding Flamethrower, The crank broke after about 30 runs. It didn't run any better, and thumped like a 500cc BSA single. Crank just couldn't take the double whammie of 2 cylinders firing at a time.

Hence "double the amplitude"!

ARN

[Nick Campagna]

We all talk standard crank, but there are multiple possibilities. With the front crank throw at 12 o'clock, the second crank throw could be at 3 or 9 o'clock. The third could be at 9 or 3 o'clock ,depending on the second, or at 6 o'clock with the inverse of the second throw. Nothing can be assumed in this type of discussion. So, what is a std crank ? 12,3,9,6 or 12,9,3,6, or 12,6,3,9 or 12,6,9,3 or 12,3,6,9 etc ?

[A Atwood]

We all talk standard crank, but there are multiple possibilities. With the front crank throw at 12 o'clock, the second crank throw could be at 3 or 9 o'clock. The third could be at 9 or 3 o'clock ,depending on the second, or at 6 o'clock with the inverse of the second throw. Nothing can be assumed in this type of discussion. So, what is a std crank ? 12,3,9,6 or 12,9,3,6, or 12,6,3,9 or 12,6,9,3 or 12,3,6,9 etc ?

Yes, but in each of your examples, you still have one throw in each of the 90* positions.
So, for each crank, you still have exactly 8 firing orders possible. And they would all still have the odd V8 firing sequence that creates its unique sound. You're not really changing anything unless you switch to a flat crank.

ARN

[lorax]

We all talk standard crank, but there are multiple possibilities. With the front crank throw at 12 o'clock, the second crank throw could be at 3 or 9 o'clock. The third could be at 9 or 3 o'clock ,depending on the second, or at 6 o'clock with the inverse of the second throw. Nothing can be assumed in this type of discussion. So, what is a std crank ? 12,3,9,6 or 12,9,3,6, or 12,6,3,9 or 12,6,9,3 or 12,3,6,9 etc ?

Did you ever see an American V8 90* crank that wasn't 12-3-9-6

[dave brode]

Talking normal one bang every 90* cranks;

1. The what seems to be most common "sequence": GM / Mopar / AMC 18436572 [also FE/289 etc ford, same just labeled differently]
2. Flathead ford / 18436572 with 4-7 swap
3. '63 up cadillac / HO ford / LS gm / 18436572 with 4-7 & 2-3 swap.

Look at the Y block ford and the nailhead buick. http://blogs.hotrod.com/msd-ignition-co ... z2ctpYZCRA

It appears that these two are similar, but start on the opposite front corner. Follow the numbers

Nail;

4 3
7 6
5 8
2 1

Y Block:

3 4
6 7
8 5
1 2

So, that makes 5 different sequences that I see. So far...

Dave

[lorax]

All firing orders must be looked at as running firing orders, or they can look completely different than they really are.
All American V8 firing orders fire the 4 outside cylinder group, then the inside. If it makes you feel better to say its the inside 4 first, then the outside, that's fine, Same damn thing. some times the order cross criss crosses the bank, but its all still, outside 4, inside 4. Or vee a vee. Which ever floats you boat. Every engine.
Look at the Ford mod. 13726548. Looks like an outside corner and then a inside cylinder #3.
But fire the engine off, and it becomes 5481-3726.

Its the starting them ALL with the #1 that makes some of them look odd, but in reality they aren't that odd at all. Give them running patterns, and they all start looking much more alike than you might at first think.