SS Auto, Boost When Shifting
 

I have a 08 HHR SS 5sp and a 2009 Solstice GXP Coupe AUTO. The Solstice Auto will maintain boost when shifting at WOT.

Here's an example: http://www.youtube.com/watch?v=VI8PhsDS6AE

My HHR SS 5sp will dump boost when I shift, unless I "No Lift Shift". I was wondering does the HHR SS Auto hold boost when it shifts at WOT like the Solstice or does it dump boost when it shifts, like the HHR SS 5sp?

If I read your post right, you answered your own question.Let up on the accelerator to shift in a 5 spd and you will loose boost.Doubt you would let up in an auto trans each time it shifts.Maybe someone else can explain it in a more technical way.

I was thinking the same thing....... it's the lifting that's causing the boost to dump with the 5 speed. (unless you "no lift shift")

To clarify, in an Auto SS does it lose boost when it shifts at WOT, does your boost guage drop down or does it stay in boost, when shifting at WOT?

The auto keeps the revs and boost up. But note the engine managment system can control the power and torque so you boost levels may vary depending on conditions.

The only reason the boost drops on the 5 speed is when you lift off the gas they drop revs and you drop boost.

No lift keeps the boost up as it regulates the engine to keep the revs up but not to the point it will hurt anything and keeps the boost up.

Note on most new cars today the engine requlated the revs in many different ways. Most new GM cars with drive by wire will not rev over 3000 RPM in park or neutral.

My Auto HHR SS holds boost to so long as I stay on the throttle. If I let off the gas it will drop just like in any other car.

Another angle...with a puter controled vehicle as soon as you lift, even for a split second,it will dump press so it doesn't overboost with the throttle plates partially closed..in no lift mode this doesn't happen because it doesnt sense the throttle movement.With a carb type setup its not as quick so boost appears to remain high...its hard to be faster then an electron!

What your experiencing in the 5spd has always been a reason why some people prefer auto's when they boost applications.

The "no-lift" is something attempting to try and compensate for that issue.

All of my "boosted" applications below are autos.

I'm going to have to check on my auto whether the boost drops momentarily during shifting. I would think it has to drop a little bit at shift points, but not as much as a clutch shift.

Back in the late 80's I ran the B&M Transpak, set at stage 2 (performance). I would giggle when I raced the clutchers........when my frontend lifted up....it never dropped down. The stick cars looked like a fishing bobber.