berns

iTrader: (12)

i've seen a ton of people run the source directly from the turbo, that's where I've done it on every car I've owned and never had an issue. I don't see it being any different than where it is now. Pressure is pressure.

cij911

iTrader: (14)

Not exactly...Manifold pressure will vary slightly from turbo pressure...but i doubt the source is your issue...I have personally experienced this problem - once from a crappy aftermarket o2 housing and once from a weak MBC....

sparky

iTrader: (1)

Whatever you decide to do, DON'T, bore out the wastegate bypass port in the turbine housing. You can do some radiusing in the turbine housing's inlet area, but you should limit the porting work to the inlet area of the bypass port and don't touch the siamesed bypass ports or the bypass port's exit at the flapper valve seat.

Since the bypass port is siamesed with a cast divider wall partition, at the exit, or seat location there are two side by side halfmoon x-sections(on the single flapper 10.5) at the valve seat, therefore each little crescent has tiny little corners which you can't really port anyway as the corners are very near the circumference of the seat. So, as you mentioned you'd experience sealing problems as well because the flapper valve isn't fixed on the flapper arm and this allows for measureable lateral movement of the flapper valve across its seat.

If you were to totally bore out the divider wall between the siamesed bypass ports, then you would run into reversion problems from one bypass port to another within the turbine housing when the flapper valve is shut, thus partially nullifying any benefits of the twin scroll housing design.

So, any porting of the turbine housing to improve flow out through the bypass port should be limited to opening up the radius at the turn-in to the bypass port, but only at the turbine inlet area of the housing. Leave the exit at the flapper valve's seat alone. Also, don't try porting or boring out the entire axial length of the bypass port itself.

berns

iTrader: (12)

well, considering I don't have another mbc to try, I'll hook this up off the bov line and cap off the compressor nipple. I highly doubt this will fix the issue, but at least it cancels one thing off the list.

sparky

iTrader: (1)

To test out the faulty MBC idea, run a length of hose directly from the compressor's J-tube nipple to the nipple on the WGA. Then increase boost incrementally by adjusting the threaded wastegate actuator rod. Since you'll have eliminated the MBC from the boost control loop, then boost should no longer creep if in fact your MBC was causing the problem.

BoostINurI

iTrader: (4)

This worked on my friends 1g dsm with his new evo3 16g....i know it's for a dsn turbo, but maybe you'll find some good info.

http://www.dsmtuners.com/forums/arti...p-porting.html


-Dave

berns

iTrader: (12)

that's a lot more work than just swapping out the controller. I'll switch up the lines and if not that, i'll call hallman tomorrow and have them send me out a replacement.

CMB

iTrader: (5)

Good luck

R/TErnie

iTrader: (32)

#1) I seriously doubt you're hitting 25psi at 7-8k.
#2) Low RPM overboost is not creep... that's spiking/overshoot.

Use the EBC through the factory ECU and throw away your MBC.

berns

iTrader: (12)

I'm in NY now. No more Hartford for me, thanks for the offer though. If you want to throw it in an envelope and send it my way, I'll send it right back after I throw it on. PM if you're down, if not, I understand.

And no, I'm not hitting 25psi at 7-8k. I'll see if I can get a video of my boost for you.
All I know is that the boost is not being controlled well. Many people have a lot of luck with the Hallman, I don't have a unique setup that should be any different.

Boost flys right to 20, then slowly moves up to 25-26 in 3rd gear, and like I said, it goes up to 28-29 in 4th and up.

I checked for leaks, came back with nothing. I just taped into the Bov line for the mbc and capped off the compressor nipple, there's no difference in how the car is boosting.

If i just used this car for drag racing, it'd be fine. High rpm and shifting at redline, the car boosts normally, after each shift it's usually at 21psi and then tapers from there. But normal driving, and full throttle from anywhere around 2-4k will result in what I"m talking about.

BluEVOIX

iTrader: (69)

Guys its the o2 housings fault 100% . Dont port the wastegate or turbo etc... Just the little hole inside the aftermarket o2 housing that merges the wastegate exhaust into the main exhaust stream.

Currently I am running the PPI Megan Swain coated o2 housing. I originally had the perrin boost controller. Everything was running fine until I got the o2 housing. When I installed the o2 housing, I had boost creep. The 1st and 2nd gear pulls where fine for the most part, then it would creep bad in 3rd and higher gears.

At first I thought it was the boost controller so I purchased the Greddy EBC. Same thing was happening. I could not control boost. It kept creeping. Still I thought it was the boost controllers fault so I purchased the Hallman in-cabin mbc. But I had the same issue!

Finally after researching to see what people did that had results for boost creeps, and found it was the wastegate merger hole being too small inside the o2 housing. I then did more research online for different cars etc... So I decided to port that hole.

The first time my friend who did the porting only took off a little of the material around the merger hole. That made a little difference. The car would no longer creep to 28-30 psi in higher rpms higher gears. But it would still creep to 24-25 psi when I only set it to 21 psi. So thats when I did even more research on how big to make that damn hole.

Last attempt, we took that damn o2 housing off again and I had him take off a lot more material. But we still kept the same design shape of the merge hole, just larger. After installing it back it was back to boost how it should. Same way how the stock o2 housing was.

Also I want to add this was all done at least a week apart. So I did plenty of driving in between each change to rule out weather conditions, ecu adapting etc....

I dont want to make this post seem like I'm flaming you, so please dont take it the wrong way. Just trying to share with you that everything your about to do I have already experienced and tested first hand. So just save yourself the money and headache.

Also in my opinion there is no such thing as being too big of a hole on the wastegate merger side of the o2 housing. As long as you dont mess with the wastegate on the turbo hotside, flapper etc.. Also as long as the angle of the merger is not changed in a way that would cause more turbulence then everything should be fine.

Remember Buschur sells the megan o2 housing and even he ports the inside.

berns

iTrader: (12)

Dude, I appreciate your long posts and your insight, but i have STOCK o2 housing... Nobody with a stock o2 has had this issue.

partyboy1122

iTrader: (16)

Why wouldn't you want a small turbo to creep?

Anyways, I solved this problem on numerous cars by porting the WG flapper as shown:



Like many mentioned check your MBC also.

Chris Moore

I had bad boost creep after my Megan o2 housing, I just gave the wastegate actuator arm 1 turn out and that fixed it. So far, this is the best fix for boost creep on these cars I think. Although, like Sean said, since your on the stock o2 housing I think there may be a problem with your MBC.

R/TErnie

iTrader: (32)

check your wastegate actuator turn buckle. Try adjusting it.

Put a restrictor in your boost source to your MBC. Try again.

Report back.