question to those running MBCs above stock boost levels
 

I'm hoping for some feedback from individuals running manual boost controllers on the stock twins above factory boost levels. From what I've read, the inherent flaw with a MBC occurs during attempts to achieve levels of boost above the factory wastegate setting. In which they have the tendency to hit full boost then taper off till redline.

I was wondering, does anyone have any experiences with a MBC above factory levels (13-15psi for example) that holds boost constantly to redline without tapering. And if so, what boost controller are you using.

I'm converted to non-seq. and use a mbc needle valve at the wastegate actuator. I used the write up on rob robinette's site as reference to installation. My PFC shows .85 bar constant till redline. Well sometimes its goes... .85/.86 .85/.86 .85/.86 but you get what I mean ;).

Jeremy

I have non-seq twins and a turbosmart mbc locked into 15 psi. I hold a strong 14-15psi all the way to redline. Honestly it waivers a little but nothing major, always at or above 14 psi.

IMO, if your boost is tapering off approaching redline, this is a sign of a lack of capacity of something other than poor function of the boost controller (restriction in air intake and/or exhaust, or weak turbos).

BTW, the above applies only to ball-spring controllers. Needle-valve controllers are just an adjustable "pill," and still rely on the stock PC & WG solenoids to control boost, and, therefore, will not control as well.

Any boost controller may not sufficiently limit boost (boost creep) if the WG is not capable of enough flow.

I run 13 psi on a needle valve boost controller. It holds strong to red line. Those who have tapering off, will have it regardless of boost controller.

http://www.robrobinette.com/boost_controller.htm

16 psi here, non-seq. on a home cheapo needle valve, till redline... Will see how the el'cheapo BC valve will work w/my new rx6b setup...


:peace:

I am running dual Hallman Pro-RX's and my boost holds perfectly until redline. Adding an MBC shouldn't cause a loss of boost as redline approaches.

IM using a DAWES DEVICE Boost controler (ball & spring) along with a Power FC.

I run 1 bar (14.7psi) & haven't notice any boost creep or high rpm drop off.

Granted, I don't just focus on my boost gauge while going WOT on the street/track, but on the dyno it stayed steady.

1 bar = 14.5037738 psi

I was approximating............my bad

IM using a Auto Meter Sport comp gauge, but thanks for being an asshole & straightening me out. I know alot of engineer's lost sleep over that 0.2 psi misquote.

I'm not being an ass.. sorry. That size font was just off googles website.

And yeah I lost .2 hours of sleepies :( Sorry for trying to help.