2009 pontiac g8gt 6l80e shift point question

[gmonde]

just installed the lower gear ratio rear 3:45 (from a 2:92) ,, I have been working on the shift points @ full throttle and if any one knows the logic for the full throttle shift speed along with the full throttle rpm -example :I had the full throttle rpm @ 5500 and speed for 1-2 @ 25mph and 2-3 @55 mph ,, during the run it would hit the chip @ 6200rpm 1-2 shift and the same for the 2-3 ,, I took 5mph out of the shift speed table and it helped but any input would help me make educated adjustments ,thanks gmonde

[Ben Charles]

These things need to be mathematically dialed in... post the tune

[hivoltagedriver]

I set my WOT shift rpm where I want it to shift, and dial in the mph to make it happen. I can tell you that you are commanding too high of a mph to make it shift right with those gears. If I remember right, with 3.45's, I usually command a 1-2 around 24ish? and a couple of hundred rpm below the rest of the gears. I would have to open a tune when I get home tonight and take a look. 1-2 is usually the problem because it hits it so fast.

I know with my 3.27s in my car, shifting at 7000, I command it at 27mph and 6800rpm for the 1-2, then 7000rpm for the rest.

[gmonde]

[ATTACH]68121 here is the last change
tunning school trans mod g8gt2 manual presure change-pe and maf gear change
yeah I am at 20 mph and 5500 for the 1-2 shift it made a difference ,,I thought the shift calculation would have to be timed mathematically

[Niemer]

Just use Bluecat's tool, makes it so much easier.

https://www.hptuners.com/forum/showt...Table-Software