Boost Creep
06-03-2023, 04:18 PM
#1
Newb
Thread Starter
Join Date: Oct 2022
Posts: 12
Total Cats: 0
Boost Creep
I am currently trying to get my 1.6 turbo miata ready for a dyno tune, and I know the setup I have is known for some sort of boost creep. I just installed the turbosmart in cabin boost bleeder to help prevent boost from creeping. Is this going to be enough to prevent it? From my understanding, it just will bleed a bit of air out and prevent me from overboosting. Is this correct?
Reply
0
0
06-03-2023, 07:13 PM
#2
Retired Mech Design Engr
iTrader: (3)
Join Date: Jan 2013
Location: Seneca, SC
Posts: 5,009
Total Cats: 857
No. Manual boost control bleeds some of the air that opens the waste gate. This raises the boost.
If your wastegate is set for 10psi, and that is what you want all the way to redline RPM, then boost creep, OEM if it exists would raise boost with RPM landing at, say 10psi.
So, if you want a steady 12 psi, the manual boost controller will do what you suggest. Just know that it will raise the low boost, not suppress the high boost.
typically, people select a wastegate that is set for 1/2 to 3/4 of desired boost, and then control with either a manual or electronic controller up to where they want to run.
Next: creep is not necessarily a bad thing. Only if it endangers your engine due to rod-bending power, or too small of injectors, such that you need to limit the boost.
Last: a small amount creep can be controlled by moving the supply to the wastegate from the compressor outlet to after the intercooler. EDIT: no, that is to fix boost droop, not creep. DNM
DNM
If your wastegate is set for 10psi, and that is what you want all the way to redline RPM, then boost creep, OEM if it exists would raise boost with RPM landing at, say 10psi.
So, if you want a steady 12 psi, the manual boost controller will do what you suggest. Just know that it will raise the low boost, not suppress the high boost.
typically, people select a wastegate that is set for 1/2 to 3/4 of desired boost, and then control with either a manual or electronic controller up to where they want to run.
Next: creep is not necessarily a bad thing. Only if it endangers your engine due to rod-bending power, or too small of injectors, such that you need to limit the boost.
DNM
Last edited by DNMakinson; 06-14-2023 at 06:34 AM.
Reply
0
0
06-03-2023, 07:33 PM
#3
Newb
Thread Starter
Join Date: Oct 2022
Posts: 12
Total Cats: 0
So right now I have an 8 psi wastegate, non adjustable. But what your saying is that I should run a 6 psi wastegate and have the controller toggled to about 9-10? That would be able to prevent some sort of overboost/ creep as well, no?
Reply
0
0
06-03-2023, 11:24 PM
#4
Retired Mech Design Engr
iTrader: (3)
Join Date: Jan 2013
Location: Seneca, SC
Posts: 5,009
Total Cats: 857
I don’t know your set-up; or your goals. I’m just trying to give you concepts. To me, if your setup can live with 10 psi peak, I’d try the wastegate you have. Chances are it will be fine, especially if you move the source after the intercooler.
Start with no bleed (controller).
Assuming you have an ECU with overboost protection, set it to a safe place before you start tuning.
DNM
Start with no bleed (controller).
Assuming you have an ECU with overboost protection, set it to a safe place before you start tuning.
DNM
Reply
1
1
Thread
Thread Starter
Forum
Replies
Last Post
