2004 L26 Grand Prix GT - Wild Cylinder Skewing from Factory (Discussion)

[tylerbinski]

So after some head scratching, digging and research I have determined that in 2004, 2005 GM skewed the NA vehicles with the following.

This only applies to Naturally Aspirated L26 equipped Grand Prixs.


I am searching for the reason behind this. My only guess is that they determined the volume of air to be different per cylinder and adjusted the fueling to match.

EDIT: Yes, Bio - good point, The rear manifold does infact flows better than front.
** would this mean more fuel required in the front to combat KR or less fuel since less flow ?
( i would guess more fuel)

Can we get a discussion going here?

I have never seen individual cylinder skewing from STOCK before.

I have confirmed with multiple 2004 and one 2005 GP stock bin files.

http://www.grandprixforums.net/lf-s...t2-l26-non-supercharged-57784.html#post739989


When I got turbo, I will be definitely setting them all to 100% and then making adjustments based on plug readings and whatnot.

 

[Bio248]

well, really the rear manifold flows better than the front, so isnt that skew backwards from what it should be?

 

[tylerbinski]

Update: Here is the 2005 Skewing...

 

[tylerbinski]

well, really the rear manifold flows better than the front, so isnt that skew backwards from what it should be?

Bio - you are right, This is a fact that the rear manifold flows better than the front.

All maps i have seen list the cylinders in the same order (3,2,1,6,5,4) I'd have a hard time believing this would be incorrect. - Tho I spose it is possible

I'm no wind tunnel or flow tester so i'm not sure which ports would see more air.

If anyone wants to take a crack at it, I have listed the image above with the cylinder ports numbered.