hey all

what is the typical cause for a boost pressure drop at transition...say 12-6-14 boost pattern...or a 12-7-15 boost pattern??

I have my own ideas but am wondering if anyone has any good input.

am finally done tuning for a 12-9.5-15 boost pattern and am ready to inch up the boost and retune..however I noticed today that Im getting a pressure drop at transition to around 7psi from 12 primary to 15 secondary.

Im using the manual boost controller and the pfc to control boost until i get the profec b.

both are installed correctly...I have new sensors and actuators.

j

PS...Im also having a problem controlling primary boost...with the precontrol closed and not allowing any prespool I am able to get full boost on the primary turbo...but with the precontrol open enough for prespool I cant boost past 12 lbs.

my goal is a 16-14-16 boost pattern or thereabouts...

the pfc sucks at controlling boost btw. hahah

 

"what is the typical cause for a boost pressure drop at transition...say 12-6-14 boost pattern...or a 12-7-15 boost pattern??"


-Got the same problem on my 95 FD. Was a Missing restrictor pill in the wastergate actuator line.

Serge

 

cool..thanks for the info...

any other ideas guys?

 

Hi Artguy,

Is your Profec installed into the Pre-control line? Or just the Wastegate line?

If your getting a big drop during the switchover then I think your pre-control pill is the wrong size. I think you might want to add a larger pill in the pre-control line.
However not to large... you might get boost spikes.

I think My pattern is 12.5 - 15 - 14.5. I'm using the Blitz SDC-ID.

Check the Lightning site before attempting to change pills though...

jc.

 

im ordering the profec...still using the manual boost controller...was thinking i might need to go with larger hoses and needle valves possibly...or wait for the profec

j

 

Hi Artguy,

You might want to check if there is a pill in your pre-control line and what size it is?

jc.

 

Hey J

Do you have access to a datalogit? We did alot of testing on minimizing the down curve during the transition ( Nocab72 and I ) If you log, lets say, a 2000rpm->7000rpm pull in 3rd gear, that will give you a good idea on what is happening with the boost. Doing a 16-14-16 is not granular enough to tune the boost and minimize the drop.

Nocab got his transition down to less than .5 seconds by adjusting prespool settings (using a datalogit) and 1.5 turns out on the prespool actuator arm. I tuned the time down with the AVC-R.

If you can get a repeatable curve (get a couple of logs done) I can give you my spreadsheet and graph that will allow you to visualize the overall curve like below.

 

wow...nice chart! the datalogit is great isnt it?

Ill do some logs...Im thinking i may have to adjust the length of my actuator as well...actually tried that yesterday and thought it solved the problem...but no luck...

j

 

I took the pills out btw...I am using the manual boost controller to handle the flow now.

thanks for the input guys!!


any other ideas?

j

 

Artguy wrote:I took the pills out btw...I am using the manual boost controller to handle the flow now.

But what is wired for the pre-control?

jc.

 

a needle valve is in place where the pill used to be I believe....Its been so long since i ran the stock setup that I cant remember if there was a pill in the precontrol line or not.

j