I was told that I would need to buy an upgraded actuator to see 28psi on my BBK Full. Is this a accurate statement? Currently deployed to Iraq and for some reason when I try and use the search function Im blocked from the site, but normal posting im fine?? Thanks in advance!

Lau'San

 

Not to the best of my knowledge.

 

No not true..before engine build I tried it a few times for the hell of it...had NO problem hitting 28 psi in 4th.

 

My friend is running over 30 on his with the stock actuator.

 

Absolutely not true. The stock turbo can spike over 28psi, why wouldn't a BBK?

Stock OEM wga, pump gas, using GM BCS. I dare you to try and find a turbo that will hold a flatter boost profile at this level (even the FP Red likes to taper):



On alky, w/o pushing it I got this:


You could run 35psi on this turbo, no problemo, midrange wgdc is only around 80%, but after 5500rpm its at 100%.

Stock wga, factory-preset preload, as it came from CBRD. My turbine housing is ported to high hell, so that may be limiting the amount of boost (but not power) it will make up top.

 

Also, on the street, 3rd and 4th gear, it can hold over 26psi at 7500rpm.

 

The standard WGA works fine, and on my personal IX, had no issues running the 29psi i had my car tuned at. We tested a higher pressure WGA and showed no improvement.

 

Thanks guys for the replies! Saved me some cash!

 

I was going to say this ^^

 

You were told wrong. Who ever told you that is trying to get you to spend moneyz or trying to get your moneyz! :X

The stock WGA can hold 30psi NO problem you can even hit 33psi and still be okay, just make sure the tuner knows his ****.

 

Or just misinformed

 

That too, haha.

 

Upgraded actuators have very little to do with boost holding ability. This is another subject that would be better served if everyone new what their exhaust manifold back pressure was.

At 28psi your manifold back pressure is likely around 45psi or better. That 45 psi pressure is trying to blow waste valve off its seat. the gate actuator spring pressure tries to keep it closed. There would be very little difference between a 15psi spring and 22psi spring. They both get blown open easily with 45psi. The 22psi stays closed better initially 3500-5000 rpm. thats why you see a torque hump on dyno graphs with the switch to HP actuator. at higher rpm where the back pressure climbs the graph will look the same.

The mechanism that helps hold boost is adjusting the valve with three or four turns of pre-load. this limits how far the valve comes off its seat. More gas is forced over turbine giving the ability to power more boost at high rpm. This also does the same as HP gate spring in that it causes a bigger torque hump at lower RPM.