Problem with Bullseye Power turbine housing

[95DSMTurbo]

I have a 95 GS-T with a big 16g, Bullseye Power 8cm turbine housing w/ 38mm flapper, and a MBC (see profile for other mods). Everything works great except that I can't get my boost to stay put!

If I turn the MBC down low, my boost spikes to 18 psi, settles down to 12 psi from 3 - 5k rpms, then creeps up to 14 - 15 psi and stays there until redline.

If I turn the MBC up higher, my boost spikes to 20 psi, settles down to 14 psi from 3 - 5k, then creeps up to 17 psi until redline. If I go WOT in 5th gear on the highway, the boost bounces back and forth between 17 and 20 psi.

Does anyone with this housing have the same problem? I'm not sure what could be causing this... I expected rock solid boost control with this housing. Is it possilbe that the 38 mm flapper is too big? I noticed that the wastegate arm runs REALLY close to the o2 housing flange... could it be rubbing or getting caught on the flange?

Any advice that you guys could give me would be greatly appreciated.

 

[hostile]

What kind of o2 housing are you running?

 

[DSM Ghost]

It sounds to me that you need to port the 02 housing or you need to get a bigger 02, let us know what you are running now

 

[95DSMTurbo]

I am using a 2.5" mandel-bent o2 housing with internal dump from punishment racing. My downpipe is 2.5" expanding to 3" after the flex, and my catback is 3".

 

[95DSMTurbo]

anyone know what could be going on?

 

[sunflashx]

I've had boost leaks cause boost control issues. I'd suggest pressure testing if you haven't recently.

 

[doug]

Usually boost creep issues are because of either the wastegate passage or the O2 housing. Maybe you could ask Bullseye-- when I wrote them once asking some questions, they were very responsive.

 

[hostile]

Which actuator are you using with your new housing.

I would suggest changing to the 15psi actuator instead of the stock big16g one.

With a larger puck the exhuast pressure has more potential to blow open the wastegate.

When it does this it causes the boost to drop.

 

[95DSMTurbo]

I am still using the stock big 16g wastegate actuator. Where can I buy a 15 psi actuator? (preferably somewhere that sells them cheap )

 

[1029TSG]

The Bullseye housing has an adjustable lever, make sure its not set too tight when you hook up the actuator. It could also be too loose, the actuator must be stretched appox. half the width of the lever when installing it.

 

[hostile]

You might be able to get one from precision turbo, turbonetics, or hahn racecraft.