MSURacing

iTrader: (1)

Because the O2 sensors control the closed loop operation bank to bank, not cylinder to cylinder. So if your original firing order is 18726543, then you change it to 18436572, your conputer doesn't know any difference.
18726543
18436572

With the two numbers on top of each other, you can see that the comuter thinks its firing #7, which is on the odd bank. But it is really firing #4 which is on the other bank. So now it thinks that the odd side needs more fuel and the even side needs less, so it compensates.

Trust me, I have seen this first hand. Now, if you put it to batch fire, it wouldn't know any difference anyways because you are just dumping fuel in.
In this situation, you would not be able to see the difference on the top end when the injectors are on for longer periods of time, but at lower on times, it makes a huge difference.

Hope that helps.

MadBill

Since the injectors are fired sequentially (fire one at a time) on LSx engines, timed relative to intake valve events, a change in firing order would leave the affected injectors out of synch. This could affect emissions and O2 sensor readings. One would have to swap injector leads, just as they would plug wires or, in the case of coil-on-plug, 12v. leads.

<EDIT: Oops! Missed MSU's post>

fast98

iTrader: (16)

on old sbc's they had a crossfire problem with the 5 and 7 cylinders, this cam is meant to correct that, i have never heard about fuel problems between the two. but i guess its possible

HALLZ

iTrader: (1)

WOW,
This is starting to sound like Ford tech, "For a HO firing order swap the injector and plug leads on the EEC to match that of a 351."

"After all the parts are installed, you will need to reroute the spark plug wires. The firing order will now be 1-3-7-2-6-5-4-8, using the HO pattern. You will NOT need to change any fuel injector wiring in your stock harness for this conversion, no matter what anyone else tells you!"

Some change the inj,...some don't, some feel a diffrence some don't.

With a LS1 until I hear of a great improvement (like 20-30+hp) I agree,.why change it after all GM did'nt with all the R&D for the LS7 so.............I would assume that it is not advantajous.

JMO

ArcticZ28

iTrader: (14)

Eliminating successive-bank fires such as the 5-7 fire also helps in scavenging the exhaust being that they're both fighting for space in the primaries on the exhaust stroke.

MSURacing

iTrader: (1)

There would not be an advangtage to do it, just letting you know what to do if you try it!!

MadBill

Unless the crank is changed, none of the many possible firing orders will eliminate the situation of some pair of adjacent cylinders firing only 90° apart.
As far as there being no value in changing FO, I doubt GM did it for both the Gen III/IV SB and the gen V/VI BB on a whim...
And if I was having a custom cam ground, I'd do it just to drive some future mechanic crazy trying to figure out why it was misfiring when he carefully wired the plugs 1-8-4-3-6-5-7-2...