boost creep help??????

[cbr600teardrop]

i have a 90 gsx sence iv put all my parts on iv got realy bad boost creep 3in down pipe test pipe cat back fmic 2g manifold iv seen on here its because air is like electrisity it will go the least restrictive way and my 14 b has some bad desing but what about the evo 3 16g or are there other ways to fix it

 

[VancTalonAWD]

Boost creep is usually a result of the wastegate not actuating properly or enough, allowing exhust gas to bypas the turbine and maintain a constant maximum flow. Check that your wastegate opens properly and all the pressure lines between it and the boost controller are hooked up correctly. Changing to a 16G will not fix a boost creep problem.

Edit: What are your boost controller settings?

 

[grnchevyz]

i have a 90 gsx sence iv put all my parts on iv got realy bad boost creep 3in down pipe test pipe cat back fmic 2g manifold iv seen on here its because air is like electrisity it will go the least restrictive way and my 14 b has some bad desing but what about the evo 3 16g or are there other ways to fix it

#1- Not flaming just gonna point out that you should really spell/grammar check before posting or some people will jump all over you for it.

#2- Boost creep defined in a VERY simple way is caused by the wastegate not opening (actuating) enough to let exhaust gases through. That being said, check the vacuum line to your wastegate actuator for cracks/kinks. If here's nothing there, make sure the actuator arm moves freely and fully by pulling on it towards the "intake" side of the turbo. It'll be tight but it should move about 1/2 inch or so. Lastly, you could take the turbo off of the car, disconnect the wastegate arm from the housing and make sure the flapper opens up 90 degrees. If it doesn't, a little porting/shaving will be required and should take care of your issue.

 

[JusMX141]

...you could take the turbo off of the car, disconnect the wastegate arm from the housing and make sure the flapper opens up 90 degrees. If it doesn't, a little porting/shaving will be required and should take care of your issue.

You've obviously never supplied pressurized air to the actuator while the o2 housing is off and noted how far the flapper actually opens.

Porting the housing so the flapper opens 90* does nothing....unless, of course, you have an actuator that allow the flapper to open more than 3/8".

Here's how far the stock actuator allows the flapper to open:

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I believe the reason the O.P. is having trouble is his exhaust system is simply too large and free-flowing for his car. I know, I know....you can never have "too large" of an exhaust system, right? If it were a 2.5" system he would actually gain a little off-boost response, not have a single problem with boost creep, and the car would still pull just as hard on top with the 14B or even a 16G.

 

[grnchevyz]

Porting the housing so the flapper opens 90* does nothing....unless, of course, you have an actuator that allow the flapper to open more than 3/8".

Which I do and I apologize, I was under the impression that the stock flapper was in fact opening as much as an e3.

He could port the wastegate wall in the O2 housing to make it less of an abrupt turn for the exhaust gases to go through. However you are right that a 2.5" would lessen if not get rid of the creep but that may not be one of his options.

 

[JusMX141]

Actually, a closer look at the photo I posted will reveal that the turbo in the picture is, indeed, an Evo III 16G. All Mitsubishi actuators provide equal travel.

The only actuators that I've seen provide adequate travel (but STILL not enough to permit the flapper to open 90*) are Garrett actuators.

But you are absolutely right....porting the wastegate hole itself, or porting the housing to direct airflow toward the wastegate hole will all help drastically- probably more than allowing the flapper to open further could do.

 

[cbr600teardrop]

thanks for the replies but all my air lines are fine they are all new i just installed a greedy boost controller but yea i shot 20 psi from my compressor in my garage to it and it don't open no 90 deg. where can i get a wastegate to do that from for a good price again thanks for the response

does anyone know where to get a wastegate actuator that will open all the way for a good price sorry to beat a dead horse

 

[JusMX141]

Allowing the flapper to open 90* isn't going to solve the problem, either.

 

[cbr600teardrop]

ok what if i buy a 50 trim turbo for the mitsu flange

like a precision or garrett

 

[VancTalonAWD]

Might be a problem with your boost controller settings. The Greddy spec II controllers can be difficult to set up so that the boost levels at a constant value.

What are your settings for Start boost, Limit boost, and gains?

 

[cbr600teardrop]

45
20
0
but i had the boost creep proble befor i installed the boost controller

 

[seamus7]

i had the same problem til i got rid of the internal wastegate and put on an external wastegate. it was like night and day!

 

[Calan]

Porting the wastegate passage on a 16g will help, but it can also make the flow more turbulent if not done correctly. (IMHO the flow there already sucks due to the 1/2 teardrop cross section and the vertical wall at the back of the WG opening).

I ported everything and got the flapper to open much wider...and then built a new actuator using the Peeper's Mod. It definitely helped with creep, but it also limits the control you have at lower boost. And it takes a lot of experimenting with arm length, flapper travel, and spring force to get it dialed in. But once I got it just right, my spiking and creeping were gone.

If you aren't comfortable with the fabrication and modification, Matt may help you out. I think at one time he was going to sell a few of these, but it's been forever since I've talked to him on here.

Without these types of mods or an external gate, 14bs and 16gs will just creep on a free-flowing exhaust. It's a law of nature

 

[aaparker]

i had the same problem til i got rid of the internal wastegate and put on an external wastegate. it was like night and day!

Agree

When I put on my 2 1/2" exhaust w/ a test pipe it creeped about 4 psi or so. Only way to fix it is to get a waste gate that can expel more pressure. The wastegate cannot expel enough to cope with the velocity you are getting with the new exhaust. Best bet is an external wastegate or a port job. There is a post by Chadillac2000 about his porting of a evo 16G may help. Or put a cat on.

 

[cbr600teardrop]

any of you guys think that a 50 trim will do away with the boost creep

 

[LandoAWD]

This is your ONLY warning to type properly. When you take the lazy way out, you are less likely to get help, and it makes your post useless for others with similar issues.

Think, then post.

 

[JusMX141]

any of you guys think that a 50 trim will do away with the boost creep

Not if you're running 10psi, which is where you'll have to keep a 50-trim until you upgrade your fuel system.

If you're running a 50-trim at that low of a boost level, a 14B at 15psi would probably feel faster.


This may come as a shock to you, but if you had a slightly more restrictive exhaust system I think you'll find your boost creep problem will disappear. This will create a little more backpressure in the turbine housing, which will enable wastegate gases to pass through the wastegate hole.

 

[shaggyslaser]

i had the same problem til i got rid of the internal wastegate and put on an external wastegate. it was like night and day!

When you ran an external wastegate, did you have it routed back into the exhaust or was it an atmospheric dump?

 

[No_Skillz]

No one is suggesting porting the wastegate passage along with the use of a larger flapper?

 

[shaggyslaser]

How would you use a larger flapper?

Would porting the wall between the wastegate hole and the compressor outlet work? The exhaust gasses being expelled from between the wastegate port and the flapper valve would not have to make as much as a harsh turn.

 

[LandoAWD]

No one is suggesting porting the wastegate passage along with the use of a larger flapper?

Thousands have, but one would have to operate the SEARCH function to procure nuggets like this...

 

[JusMX141]

How would you use a larger flapper?

If you port the hole larger, the stock 31mm flapper would then become too small to cover the hole entirely.

In steps Mr. 34mm Wastegate Flapper.

 

[No_Skillz]

In steps Mr. 34mm Wastegate Flapper.

You talkin' 'bout me?

I just feel elitist about my internal gate which is 38mm and forces me to run 20psi minimum.

 

[cbr600teardrop]

why would i have to run a 50 trim at 10 psi when i can run my 14b at 16 or 18 psi why couldnt i run the 50trim at the same psi i mean 18 psi is 18 psi right?

 

[LandoAWD]

why would i have to run a 50 trim at 10 psi when i can run my 14b at 16 or 18 psi why couldnt i run the 50trim at the same psi i mean 18 psi is 18 psi right?

No, and TYPE PROPERLY. Warning given.

Think of it in simple terms...you have 2 garden hoses. One is a puny little 1" diameter hose and the other is a beastly 4" hose. Both are set to the same water pressure. Which one will dump more water?