Boost Creep

[ajpturbo]

If your boost is hitting in the 7's don't set your boost cut 7's...You can get little boost spikes then your controller will go into boost cut...You have it set to close to your desired boost...You need more headroom...It sounds like you are trying to use the boost cut as a boost limiter

The controller attempts to lower boost quickly and abruptly when it reaches boost cut....Raise the boost cut to 9-10...I think it even says in the manual to set boost cut a few psi over what your desired boost is

 

[ajpturbo]

I'm not sure why if you have the 3 psi spring in there you are boosting that high.

I have the 3 psi spring and can go down to about 5.4 psi and that's been in 30 degree wheather in Pittsburgh, Pa

 

[5lho]

Just another one of the little things that make turbos complicated.

If it's true boost creep, nothing will control it, as it's a mechanical/physical function of the turbine side and wastegate sizing.

If it's just a boost controller issue, an electronic one might be a better option.

 

[ajpturbo]

Just another one of the little things that make turbos complicated.

.

It's really not complicated.....If all else fails just run the vac line from the compressor to the bottom of wastegate and see where you are at boost wise.

 

[5lho]

Yeah, and what if it's still overshooting target? It's complicated if the WG and turbine side are physically too small to allow for control by the WG. There's no fixing that. I've been down this road before, several times.

 

[ajpturbo]

He isn't the only one with this kit. He has the same WG as everyone else. So he has a wrong spring or wrong plumbing somehow.

 

[5lho]

Yeah, you're probably right there. It also may be just real cold where he is right now and that ain't gonna help.

 

[04sleeper]

The kit comes with 5 psi springs with the stock exhaust in place. They usually see around 5.5 psi with this set up. Add free flowing exhaust and the boost picks up a couple of psi. This is what happened with mine when I added a full 3" straight through set up. Picked up 2-2.5 psi.

He would have to try lighter springs if he wants to run less psi.

Just because a spring in a kit is "Supposed to be xxx psi" doesn't mean it will be. It all relative to the set up as a whole.

I would suggest going with a lighter spring set up.

I do not feel it is a wastegate size issue.

 

[Quesplosive]

Should be 60 something when I get off in a few hours. Ill run off the springs and set the over boost to 8.5. With the 5psi springs I should see 7.5 max I guess. I really want to see if it holds a psi. I do not have any restrictions in my exhaust except the over axle pipes. Everything else is 3 inches. As stated above me I am sure that plays a factor also. Like I said this is only happening now since the weather has gotten colder. Im new to the turbo world and learning as I go. Thanks for the input so far guys.

 

[ajpturbo]

In general if you are trying to run very low psi then wastegates need to be larger to bleed the exhaust by the turbine. And when sweeping through the upper rev range really fast it's really asking a lot to control the boost quickly with these highly efficient turbos.

Also I think when you have a certain spring the number represents the psi at which the valve will start to crack open. So a little higher boost is normal for a given spring pressure.

Wastegate Spring Rate and Spring Pre-Load Explained - YouTube

 

[Jedisalami]

where does the line from the top of your wategate go?

 

[5lho]

Hmmmm, do you mean the wastegate actuator or your blowoff valve? The first goes to whatever form of boost controller you have and the second goes to engine vacuum.