New GM Firing Order Conspiracy?

[Infomaniac]

OK I was looking over a diagram I made a while back comparing the old GM firing order and the new GM firing order. I was trying to see where claims of more power from the new firing order might happen (claims not from GM). GM claims more durability. Here is the old firing order on top and the new firing order on bottom. Big difference huh?
http://members.cox.net/crazyokie/FO.jpg
GM claims less stresses on the crank. More durability from the new firing order.
As I continued to look at the diagram some similarities bagan to appear. I then connected the last cylinder in the firing order to the first cylinder as a continuation of the engine running. See the new diagram.
http://members.cox.net/crazyokie/FO2.jpg
The firing orders are mirror images of each other. Is this a marketing play from GM? I cannot see any gains in durability. It is basically the same. Nothing changed.
Does anyone else see this?
I am going out on a limb here. Am I just a dumbass and need to get a life? Or should I get custom ground cams for every engine I build in the future?
[ November 24, 2002, 09:21 PM: Message edited by: Infomaniac ]

[Havasu Hangin']

Those look like crop circles to me...

[Dennis Moore]

Ford did this years ago, the old Chevy firing order was the same as the 302 and the new firing order is the same as the 351W (cylinders are numbered different on Fords). Must be something to it! I've heard that the latest Pro Stock automotive engines are using the new firing order for a slight performance increase. Who knows why.
Dennis Moore

[Infomaniac]

Dennis Moore:
Ford did this years ago, the old Chevy firing order was the same as the 302 and the new firing order is the same as the 351W (cylinders are numbered different on Fords). Must be something to it! I've heard that the latest Pro Stock automotive engines are using the new firing order for a slight performance increase. Who knows why.
Dennis MooreWhat is your gut feeling Dennis? Join me out on the limb.

[motor_jet]

NASCAR HAS IT GOING ON FOR YEARS, JUST ASK COMP CAMS I WAS TALKING TO THEM IN 87 DALE WAS RUNNING IT WAY BACK TRYING TO RUN WITH THE FORDS.THE GUYS AT COMP SAID I WAS THE ONLY TO CALL BESIDES NASCAR
THEY CAN'T USE ROLLERS,THIS MAKES A BETTER ROLLER

[Infomaniac]

All the history is great. Very interesting. I know it is not new. For whatever reason I just decided to try and figure out why it is better. And in the process it looked like just a marketing thing for GM's new engines. New and improved scenario.
I need someone to explain why it is better.
[ November 25, 2002, 08:18 AM: Message edited by: Infomaniac ]

[RH]

Here are a couple of quotes from articles I have seen on the new order .
There's also a new firing order that reduces stress by 7 percent on the internally balanced and counterweighted cast nodular iron crankshaft.
Firing Order
The Vortec V8s have a cylinder firing order that
better balances the forces that are exerted on the crankshaft during combustion.

[HOSS]

Sounds like a bullshit marketing ploy to me. GM is trying to seperate the old style to the new.
I say too late. Thank goodness I didn`t get that bowtie tatoo about 15 back.
GM lost what it use to have. Build an affordable muscle car for the young male population. Remember the word affordable.
Thats what Ford did in the late 80`s with the Stang. Also released pattents so the aftermarket community could flood the market with cheap upgrades. And it worked!
How many 18 year olds can afford a Camaro even used. Besides, its a piece of shit anyway. Any fender bender will cost too damn much tofix. How many affordable upgrades are there ( bang for buck) for the LT1? Yeah right!
And GM`s failure to keep Olds going really pisses me off. The Alero is really starting to sell. You see an awful lot of them being tricked out. I think they should have done some market strategy in that direction. When they droped out of drag racing it was the beginning of the end. I worked for years as a line tech at a local Olds dealership. Sorry to see them go.
In my opinion, the best built mass production cars are from Honda and Toyota.
Just quit VW and dude that is a ****in` joke!
The day you pay more than 15k for a VW is the day you got ****ed without and lube! And I do meen any VW!
If anyone out there owns one and has had AC, power window trouble, check engine lights,,,,,,you know what I meen. Don`t let them screw you. The manufacturer buys thesecars BACK like no otherI`ve seen. From what I can tell, German engineering sucks.
Gotta love those bench racers!

[DEL51]

Info,I am impressed with your curiosity.That was a neat Idea running the lines like you did,good observation.I wonder how much of a change there really is.It sounds like something they would have figured out in 1955.

[UBFJ #454]

Info -
As you know, the majority of HP is made within the top of the engine, not the bottom. The more one builds up on top, the more one should be concerned about the bottom and its ability to withstand/endure what one has put together upstairs.
With that in mind, lets look at the firing order and its affect on the crank. Let's look at this from the BBC perspective since we're dealing with bigger bores and longer strokes and, therefore more crank shear stress (lateral pressure).
The BBC crank has four (4) rod journals to which two (2) rods are connected. The firing order defines the sequence of firing and therefore, the sequence of stresses applied to the crank (the downward force resulting from ignition). If you plot the number of successive "hits" a journal takes, you'll find that in the old firing order it's two on two journals (journals 2 & 4, from front to back). In the new firing order (which I suspect was implemented solely for the smaller bores and strokes of the newer engines) you'll find the number of successive "hits" to be two on three journals (#'s 2, 3 & 4).
The latter, in my opinion, on a high HP BBC is not good (by high I mean 1,000 HP and above). Note that the BBC crank is stronger in terms of lateral strength in the rear (thru journals 3 & 4). Mainly for this reason (there are some HP considerations) I choose to start from the old firing order and swap #'s 4 & 7. This results in putting the two successive "hits" on journals 3 & 4, separated by non-successive "hits". Also, there being more mass at the rear of the crank, crank harmonics are more dampened.

[Infomaniac]

BEAR_454PE
[QB]Info -
If you plot the number of successive "hits" a journal takes, you'll find that in the old firing order it's two on two journals (journals 2 & 4, from front to back). In the new firing order (which I suspect was implemented solely for the smaller bores and strokes of the newer engines) you'll find the number of successive "hits" to be two on three journals (#'s 2, 3 & 4).
[QB]BEAR_454PE:
The number of succesive hits was my first thought. That is why I connected the last cylinder in the firing order to the first. Take another look at the second chart. Both firing orders have succesive hits on 3 crank pins.
The difference being the old firing order hitting on the first 3 pins and the new firing order hitting the last 3 pins.
I can agree that the rear of the crank having more mass will be stronger. How about the block? The rear main cap? Is there a weak point there?
Just more food for discussion. thanks for the reply.

[Infomaniac]

OK MaybeI have figured out why their are claims of more durability. With the help of everyone's input. Here is my theory:
Moving the succesive hits on the 3 crankpins from the front of the engine to the rear by changing the firing order has in effect moved the most stress to the main journals of the crank that get oiled first.
?????????

[UBFJ #454]

It's quite correct that a mod has to be made to the oiling system to correct for 1) additional stress on the rear of the crank and, 2) more importantly, to make sure the rear lifters and push rods get plenty of oil (especially true when using big Jesels). This is why all "old hand" BBC builders make them.

[UBFJ #454]

Ref: The block ... to add support to its back is why the DART Big M Block has extra webbing casts.

[spectras only]

I guess it was easier for GM to change the firing order to help the crank at the rear rather than make the cranks & journals bigger similar to the fords wink .The main caps are also beefier on the fords ,hence no need for four bolt mains in most application for 429's and 460's.BTW ,I have an LS-6 in my present boat,no need for flaming :D
[ November 25, 2002, 10:28 AM: Message edited by: spectras only ]

[spectras only]

[QUOTE]Originally posted by Havasu Hangin':
[QB]Those look like crop circles to me... , HH, I think the gm engineers were bored , made a maze during lunchtime and someone said ; what a heck ,lets try it in our engine, it might work :D

[Jet Junk]

Infomaniac:
OK MaybeI have figured out why their are claims of more durability. With the help of everyone's input. Here is my theory:
Moving the succesive hits on the 3 crankpins from the front of the engine to the rear by changing the firing order has in effect moved the most stress to the main journals of the crank that get oiled first.
?????????This is the explanation I have heard most often. Supposidly this keeps it from rattling when you first start it when there is no oil pressure.

[Fiat48]

If the Pro Stock racers are doing it (heavy hitters like WJ) then there is something there. But remember these guys will do anything for a milisecond of ET.

[Jrocket]

HOSS:
German engineering sucks.Ouch,kick me in the nuts again Hoss.. :D

[Badboat1]

Well #5 on a carb motor is the lean one and #7 fires next so swap 7 and 4 take the heat out of 5
We have also ran other firing orders for chevys as fire the outer first then the inner 1-8-7-2-6-5-4-3 oh well some pro stock stuff
Badboat1

[Badboat1]

I forgot to add you have cam and crank twist involved in this also in a car with a clutch also
Badboat1

[UBFJ #454]

Badboat 1 -
What are some of the other firing orders you've tried on BBCs? Good Points/Bad points of each on engines running 8k or less RPM.

[HM]

Do these firing order changes require different cams or cranks to match the firing order? Or can you just change the plug wires?
[ November 26, 2002, 10:31 AM: Message edited by: HolyMoly ]

[Blown 472]

Dare I ask, but has anyone done this with a ford?? :confused:

[waterslinger]

Men we run a super stock car and the Engine Builder told us that by moving 4 & 7 thay do not compeat for the same intake charge. On our 8500
rpm 327 it is good for 8HP. You can not live by dyno numbers. Spent 3 days on the dyno testing carbs. Two carbs were 3 HP a part but on the track 2 tents from one to the other.

[Infomaniac]

Started a new thread with all three firing orders mentioned here.
http://members.cox.net/crazyokie/3.jpg

[spectras only]

Just a test
[ November 27, 2002, 12:35 PM: Message edited by: spectras only ]