: Why is the left bank now the right bank?



haymaker
12-20-04, 01:36 AM
Does anyone know why the left bank numbers were changed to the right bank? I have been twisting wrenches on a lot of different engines since the very late 1950s and one thing I have learned is itís a dependable way to bust your knuckles.

To get to the point of the thread, GM was always been dependable as per the numbering and or location of the cylinders. As explained by my uncle (a few years back) if I stood behind the engine at the flywheel or from the drivers seat and looked forward my left hand could count front to back the odd cylinders 1,3,5,7 and my right hand could count from front to back the even cylinders 2,4,6,8.

One day I was working on my Eldo. with a 368 ci. Engine and low and behold, left was now right and right was now left! I later worked on a 173 ci. Chevy and it was numbered the same. My N* is the same way. Whoís bright idea was that? Did GM hire a new guy back in the late Ď70ís or early Ď80ís that didnít know his left from his right or what? Why didnít someone say your other left, of did they?

dkozloski
12-20-04, 11:36 AM
I guess the same people also decided some inlines ought to be labled front to back and others back to front. Add in CW vs. CCW on distributor rotation and it all becomes totally incomprehensible. Just the other day I discovered a Continental industrial engine with the wrong rotation distributor installed. Luckily I found I could turn the advance weights and springs over and make it all work to advance rather than retard the spark. It brought back memories of pressure spark retard in the old turbocharged Corvair Monza Spyder. Cheers!

BeelzeBob
12-20-04, 01:39 PM
There is a fairly straightforward answer to the question. I assume , BTW, that you are talking about the fact that most V-8 engines have number one on the left side of the engine in the front position and the Northstar has it on the right side??

Any engine, such as a V-8, that has two connecting rods side-by-side on a common crank pin must have the cylinder banks offset by the width of the connecting rod. This way the rods can be side-by-side on the crank pin and centered in the piston. This is called the bore stagger from one bank to the other...or simply bank stagger. For some reason, most V-8 engines have the bank stagger with the left bank being forward of the right bank.

Typical cylinder numbering convention is that the bank that sits "forward" has number one cylinder on it at the front of the engine.....so....since most V8's have the left bank forward number one is at the left front corner.

When the Northstar engine was designed it was packaged and optimized for a transverse front wheel drive arrangement. Since it was a clean sheet of paper design and was not constrained by any previous designs or tooling the decision was made early on to stagger the block with the right bank forward as it would package better in a TFWD vehicle. This allowed more room in front of the left bank (since it was rearward) for accessory drive mounting. This is important in a TFWD vehicle, especially one with a V8 engine due to severe space limitations. There is no room in front of the right bank anyway for an accessory so moving the right bank forward into that area did not compromise anything. Freeing up some room at the left front end of the engine allowed for accessory mounting, accessory drive and the torque axis mounting plate used on the Aurora's.

With the Northstar designed so that the right bank is forward the convention of naming number one on that bank was maintained also so number one ends up on the right front corner of a Northstar.

The firing order of the Northstar , 1-2-7-3-4-5-6-8 , sticks some as odd and has created a number of myths about changing the firing order for better balance, better performance, better ??????. None of it is true. The firing order for many V8 engines, including the small block chevy, is 1-8-4-3-6-5-7-2 so most people take this as the holy grail of firing orders and always wonder why any engine would be different....LOL.

If you lay out an engine block diagram and number the cylinders with number one at the right front corner, number 2 at the left front corner, number 3 on the right side, etc. you will have the representation of the Northstar layout....all the odd cylinders are on the right side and all the even numbers on the left. Now, in red, overlay this diagram with the cylinder numbering strategy of a small block...i.e...number one is on the left front, numnber 2 on the right front with all the odd numbers on the left side and the evens on the right.

Now....take the small block firing order, 1-8-4-3-6-5-7-2, and use your diagram to translate it to the cylinder numbering scheme of the Northstar. If you do this correctly (and I have not made a typo...LOL.) you should end up with 2-7-3-4-5-6-8-1. This is the same firing order as the Northstar (hint...move the number 1 to the beginning which is fine as the cylinder following 1 is number 2 in the firing order since the cylinders fire in the same sequence over and over). So....the Northstar has exactly the same firing order as the small block chevy and other V8 engines once you account for the different cylinder numbering schemes. End of urban legends....

Spyder
12-21-04, 01:01 AM
Awesome info...Once again, learned something new that I had wondered about in the past...

haymaker
12-21-04, 03:35 PM
I always wondered why but I never thought the reason would be the cylinders offset? To me the rear of the engine was still the rear or flywheel end, left was always odd and right was always even. I should have known the rules were changing when the engine got turned 90 degrees clockwise. If nothing else, it made a bunch of people start referring to the shop manuals again.

If you ask a question it doesnít take long to get an answer around here. Thanks for the explanation.