Is this normal behaviour for Caldina when boosting?

[speedracer07]

Hey all,

I've finally sorted my wiring issue's with my caldina motor into my sw20 and everything electrical seems to be running well!! I'm now seeing higher than 9psi boost and no codes!! and there is no more issue with running rich when compression braking.

My question now is that when I was testing the car last sat I noticed that the boost level seems to spike up to 14-15 psi then drops back down to 12. I'm not using any sort of boost controller and everything ECU related is stock. I'm using an OMORI electric boost gauge so it should be fairly accurate, I can definitely feel more power and then it tapers off... But it's not really behaving like it's boost creep as it's very regular. The Intake/intercooler/BOV (Synapse)/Exhaust are all aftermarket.

Could this be the waste gate actuator sticking? The car had not been driven or boosting since october so perhaps it will go away after it's been driving? clearly? Or is it some sort of feature for the ST-215 to allow for quicker spooling? (theory my mechanic was wondering about?). Finally could it be triggering some sort of safety mode? it was a cool day (about 3degrees celcius) and maybe it was seeing knock so was retarding boost? (but there was no codes and I would have thought it would drop down to 9psi and stay there?)

any body have any ideas?

thanks!!

Roshan

[99gtt]

thats normal for a st215 motor , they all do that especially if you have an after market exhaust

[cat007]

Yep. Pretty normal stuff really.

[speedracer07]

thanks!! I am running an aftermarket exhaust, any idea where I can find info on why they do that? Do the ST205 motor's do that as well?

Side question is if I decide to run an aftermarket boost controller I understand that electronic is the way to go. Any recommendations on which models work well with the caldina? Also for the stock turbo (ceramic) how high is too much boost? I've been led to believe 15psi is ok but anymore and your risking it...

Thanks again for your patience with what must be very basic questions for you all!! Nobody over here in Canada has even SEEN a Caldina GTT let alone tuned one so I'm sorta feeling my way in the dark.

R

[cat007]

1bar would be the limit for the turbo

they have a boost spike I think because the turbo is pretty small for the engine so it's able to spool quick and the wastegate isn't quick enough or fast enough to compensate

Correct me if I'm wrong anyone?

[fivebob]

They do it because the stock boost control doesn't work very well. If you fit a good quality controller then they don't spike ,and will hold a consistent boost level until the turbo starts running outside it's efficiency zone and can't supply enough air for the engine.

[Quirky]

This happens to alot of turbos when you free up the exhaust.
Especially XR6 turbos they go from 7psi to 12psi before the boost controller cuts in.

[Lac]

Yer, thats normal. I have a greddy profec b boost controller. The bizz...
i have mine with a cut out and alert a 1.1 bar, but it never gets there, but always gets and spikes to about 1.05 bar. Which is about 15 psi.
So no issue with yours.

[sergei]

I know later STIs do spike like crazy, up to 1.5 bar with exhaust, then drop off back to ~1bar.