Ok guys. Not sure what happened. On the way to class drove on hi boost. Peaked at 20.4psi in 3rd and 4th gear. On the way home, still in hi boost, I got stuck behind some slow-*** going 10mph under the speed limit. So, I drop from 5th to 3rd and floor it to go around them and boost spiked up to 21.3psi and hit fuel cut. Nothing was changed. Weather, weight in the car, everything weas the same. Only difference was going WOT from 1st to 4th, and dropping from 5th to 3rd. Would this make a difference in boost? Could dropping gears somehow create more load causing higher boost? Not a big deal, I turned the boost controller down a little but I'm still curious. Thanks

 

That's possible, I would try dropping 4th or 5th like you said and see if you notice a change in boost! Plenty of turbo cars have a good tune and still obtain a boost spike but it should be a spike of about 1 to 1.5 psi.

 

I always see a little more boost in 5th than any other gear. The lower ones are a bit less, especially first.

 

maybe i didn't explain well. I was cruising in 5th at 35mph. I dropped into 3rd to pass someone. When I dropped into 3rd I floored it and the boost went to 21.3psi in 3rd. Previously, when going sequentially 1st-2nd-3rd-4th, the max boost in 3rd was 20.4psi. Why would the boost increase just from different driving conditions? Make sense?

I know boost is lower in low gears because of the load on the engine. This is a different question. thanks

 

Its cold now thats why. When its cold turbo cars spike up all the time. Turn you MBC down

 

naw dude, the two different boost readings were within 1.5 hours or each other on the same day, same weather, same everything. must be something else.

 

maybe the turbo spooled up so quick with the instant RPM increase... the momentum of the wheel kept spining super-duper fast and spun enough to make 21.3 psi that isn't possible just by accleration...

 

Hey that makes sense. Finally an informed response. thanks for reading and answering the correct question.