Overboost (Driftmotion stuff + pt67dbb)

[Mr. Y]

Hello guys!

My setup:
- Driftmotion 7M tubular manifold (SS AC style but with v-band WG flange), actually XO2 racing
- Driftmotion wastegate with 10 psi spring and minimal pre-load (actually XO2 wastegate, 44mm tial flanged) routed to 80mm cat-back
- Precision T67DBB 0.68A/R

Problem: overboost at high RPMs, see picture for details.
What shall I do? I guess WG is sticking or something restrircts exhaust flow...
May be somebody had similar problem and know how exactly to fix it?

 

[WhtMa71]

Is your target boost just 10psi or are you trying to run more?

 

[Mr. Y]

I'm trying to run _less_ boost. I want 10psi across all RPM range and not 18psi after 5300rpms.

 

[WhtMa71]

Are you using any kind of boost controller or just trying to run off the spring?

 

[suprahero]

His wastegate would have to be stuck shut to make that kind of boost without a boost controller........right?

 

[WhtMa71]

Could be a number of problems. Vacuum/boost source, wrong settings(or just needs to play with the settings) on an EBC, weak spring or wrong spring, or just a MBC that doesnt hold boost.
Ive never really trusted the china WG's but ehh..who knows.

 

[suprahero]

I didn't read where he had a boost controller, but I guess he either has one or his wastegate is fubar'd.

 

[WhtMa71]

Yea he didnt say he had one, thats what i was trying to find out.

 

[suprahero]

Enquiring minds want to know.

 

[Mr. Y]

Ok, I've found the problem. XO2 wastegate is shitty construction. Upper shim that holds spring and can be moved by screw (regulating pre-load) is very thick. It limits valve movement so valve not fully opens. I removed all useless stuff from WG and gained about 10mm more of valve travel (but now I can't regulate spring pre-load).
Moreover, I looked WG more closely and found that it can be ported (my next step).

Hey, Aaron, any comments? Do you test parts you sell?

PS: boost solenoid is off. Running spring only.

 

[WhtMa71]

Like i said, I never really trust knockoff parts especially when it comes to a wastegate, overboosting is not good. If i were you id just go ahead and get a real Tial WG. Theres a couple of guys selling the 44mm's in the classifieds.

 

[MRSUPRA]

Get a real tial wastegate. It may not only solve these issues, but it might also save you an engine in the future.

 

[quake]

i'm running a 70mm and a tial 44mm. Trying to run a 67mm capable of 800hp with a 44mm wastegate may prove to be difficult. The lowest i can run with a 13psi spring is 13psi when it's hot outside. The same setup runs 19psi cold. Why are you trying to run soo low?

 

[Mr. Y]

quake
Why are you trying to run soo low?
There are two reasons:
-I'm in process of fixing some bugs now and road tuning. It's better to make mistake at 10psi than @ 18 psi.
-We have only 95oct here (european rating, like 91 american, I think)

B.T.W, couldn't you PM ignition timing map please for 70mm that can be run on pump with such high boost (19psi)? And what octane rating is your pump gas?