no cat back causing boost creep?

[Saff71]

Hey everyone I have a question that I hope someone can help me with. I am experiencing boost creep with an FP exhaust manifold FP green turbo and punishment racing o2 housing with 38 mm tial wastegate 3" downpipe with test pipe but no cat back yet because it is on backorder. I have a 11.6 lbs spring in the gate and a hallman boost controller set to almost no restriction. I'm creeping from 18-25 psi even with no MBC and the turbo's pressure side plumbed directly into the bottom air port of the gate with the other air ports plugged and top port open to atmosphere.
Do you think that I could be experiencing boost creep because of no cat back/ very little back pressure? I find it hard to believe but what do you guys think?

 

[Soccerguy136]

Seems like you need to plumb the air ports differently or adjust your boost controller all the way in. With an external gate a bleeding style boost controller's functions reverse. In/More pressure becomes less boost, while Out/Less pressure becomes more.

Top and Bottom exhaust ports you have correct though.

Read this post for more info/correct plumbing:

http://www.dsmtuners.com/forums/turbo-system-tech/258360-installing-mbc-using-both-external-wastegate-ports.html#post151169306

Hope this helps.

 

[AllGripNoSlipGSX]

Never heard of that one.

 

[GRAVEDIGGER]

I have a 11.6 lbs spring in the gate and a hallman boost controller set to almost no restriction. I'm creeping from 18-25 psi even with no MBC and the turbo's pressure side plumbed directly into the bottom air port of the gate with the other air ports plugged and top port open to atmosphere.

Seems like you need to plumb the air ports differently or adjust your boost controller all the way in. With an external gate a bleeding style boost controller's functions reverse.

Being that the OP has a Hallman boost controller he doesn't need to worry about it working in reverse on the external gate, because it is a ball & spring type and not a bleeder type. Plus he says it does the same thing without the controller and going straight from turbo to the wastegate. Usually an external gate is rock solid at controlling boost, but trying to run such low pressure on that green may be too much flow for your wastegate. After all, the lower you set your boost pressure, the more exhaust gas you have to divert around the turbine. You may be trying to divert too much therefore inducing boost creep. With, or without a catback you may still experience the same thing on that low of a pressure. Any reason why you are running such a low pressure on that turbo? I would try to crank it up to at least 20psi, or so and see if it can maintain that boost level without creeping. Maybe some others can chime in with some advice. Good luck!

 

[Soccerguy136]

^ You need to read the link I posted .

His problem, from my understanding of the link, is that both vacuum ports are plugged. He needs to connect them via what it says in the link depending on which setup he wants (With or without boost controller)

With both plugged it will max out the spring, like it is doing.

A 38mm external gate should be plenty for an FP Green.

Though you are right about it being pointless to run 12psi on one .