Trans Shifts delayed 400rpm

[LBSBLOWN]

I have a 2005 GMC Sierra with a Radix Supercharger and a 3.0 pulley
it makes 11 to 12 psi of boost.

Anyways I have the Shift points set at 5600rpm but the engine shifts at
6000rpm.

Anybody have any thoughts.

[12secSS]

What kind of converter? It could be too much power, as the OE setting and setup was designed for a non-boosted application. Torque converters will change characteristics when more power is applied, this will also increase it's inefficiency (more slip through shifts). This is just one possibility.

[MNR-0]

400 is good. Mine delays 1-2 by as much as 500rpm. Im getting the shift accumulartor tickeld some more to make it shift faster, but there is a limit to how fast a tranny can shift. Also bear in mind diff gears will impact the shift lag somewhat as the revs climb faster the shorter you go. Usually, the tranny takes 2 cycles to engage a shift. If it takes 3 or more, then its either starting to slip or components are wearing out. 2 cycles in my stock Monaro equates to 500rpm. In a stroker it is more like 7-800rpm.

[LBSBLOWN]

400 is good. Mine delays 1-2 by as much as 500rpm. Im getting the shift accumulartor tickeld some more to make it shift faster, but there is a limit to how fast a tranny can shift. Also bear in mind diff gears will impact the shift lag somewhat as the revs climb faster the shorter you go. Usually, the tranny takes 2 cycles to engage a shift. If it takes 3 or more, then its either starting to slip or components are wearing out. 2 cycles in my stock Monaro equates to 500rpm. In a stroker it is more like 7-800rpm.

What do you mean by "the tranny takes 2 cycles to engage a shift"?
and how do I data log this to find out?

Thanks

[98A4LS1]

^^^ I would also like to know what that means ie, 2 cycles to shift. Also, is it possible to extend shift points for example 300 rpms 1-2, 2-3, etc. regardless of TPS. In other words, the shift would occur 300 rpm's higher than stock regardless of how much you press the accelerator.
Thanks

[gamedawgx53]

TTT
so does this mean the PCM is "too slow" to compinsate for the rate of increase in rpm in a very high power setup?

If so hows the best way to correct for this?

command shift points lower and
use trial and error to make it shift where you want?

if so, How consistant is this?

[EC_Tune]

If the trans is a 4L6xE series they are not designed (in factory form) for torque above 400 ft lbs. The additional torque is causing the adaptive shifts to max out.

Take a look at your Shift Time Table.

It shouldn't be less than 250 mSec probably closer to 300 msec.

Attachment 162
Attachment 160


EC

[WorkingManPerf.]

My ls2(4l65e) does not have those tables.

2>3 shift seems long, with no way to change it.

[brh26]

The words below are from Chris in another thread about the same topic;

"the trans takes time to shift, this is especially noticeable in 1st gear since the engine is accelerating so fast. In some cases you need to allow a few hundred rpm for the trans to actually shift."

It is nothing to worry about sshifting later than the commanded rpm. Tweak the commanded setting until it shifts where you want it to.