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Old 01-12-2003, 09:28 PM   #1
Sauceboy01
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Default Boost Creep Help!

I currently have the vishnu Stage 0 + HKS Downpipe, and am experiencing some boost creep.. Here's how it goes.

1st .8
2nd .9-1bar
3rd 1.1 bar
4th 1.2 bar (hits fuel cut off)
5th 1.1 bar

Now, if i turn down my MBC, to not hit fuel cutoff in 4th gear is reducing my boost levels in all gears dramatically.

what can i do at this point?

-Danny

Last edited by Sauceboy01; 01-12-2003 at 09:35 PM.
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Old 01-12-2003, 09:33 PM   #2
SonicYellowWRX
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im guessing you need the unichip reflashed for the addition of the dp.
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Old 01-12-2003, 09:36 PM   #3
Sauceboy01
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Quote:
Originally posted by SonicYellowWRX
im guessing you need the unichip reflashed for the addition of the dp.
I wasn't looking for a GUESS..

sorry Huy

-Danny
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Old 01-14-2003, 03:49 PM   #4
AVT
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Default Re: Boost Creep Help!

Quote:
Originally posted by Sauceboy01
Now, if i turn down my MBC, to not hit fuel cutoff in 4th gear is reducing my boost levels in all gears dramatically.
That's how mbc's work. unless you have a good ebc, you'll have to get a target boost in one gear. The gears below it will be low, and the ones above it will be high.
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Old 01-14-2003, 11:05 PM   #5
cmaj7
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Default Same problem

I have a buddy who had the exact same setup, VS0 and HKS Downpipe. Running a Profec B he had the exact same problem with boost creep and spikes.

The only way he was able to solve this was upgrading his downpipe to a better flowing design.
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Old 03-09-2003, 02:09 AM   #6
mattjk
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Not true, dp is not causing the problem, I have a TXS
downpipe with no cats and I'm getting boost creep
with my VF22. A free'r flowing exhaust is just going to
make the problem worse. The internal wastegate port
being too small on the IHI turbos is the problem.

My boost creep goes from 10.5psi up to 13.3psi
at 6500rpm. This is with no boost controller at all,
the solenoid is connected directly to the turbo outlet
nipple.

This sucks because my goal was to run only 12psi...
I guess I'll have to get a re-flash and bigger injectors.

As a side note, I started getting boost creep when I
change my 2.5" rear muffler to a full 3".

Matt
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Old 03-09-2003, 02:15 AM   #7
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I'm experiencing the same problem. I've tried 2 txs hpmbc's and a greddy profec b. Same problem with both. I try to run 17-18 psi in 3rd and hit 22 and fuel cut in 4th and 5th. I'm going to try to port the wastegate soon and I'll let you know how it works.

btw, I'm running a vf30 w/txs dp
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Old 03-09-2003, 02:21 AM   #8
mattjk
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Quote:
Originally posted by morphgabbin
I'm experiencing the same problem. I've tried 2 txs hpmbc's and a greddy profec b. Same problem with both. I try to run 17-18 psi in 3rd and hit 22 and fuel cut in 4th and 5th. I'm going to try to port the wastegate soon and I'll let you know how it works.

btw, I'm running a vf30 w/txs dp
Excellent, let us know!!!

I also had boost creep on my mr2 turbo with the hks turbo
upgrade. I got it to stop creeping by re-installing the stock
muffler... I later welded the internal wastegate shut and
install an external HKS Racing series wastegate.

Matt
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Old 03-09-2003, 02:39 AM   #9
mlambert
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Quote:
Originally posted by mattjk


Excellent, let us know!!!

I also had boost creep on my mr2 turbo with the hks turbo
upgrade. I got it to stop creeping by re-installing the stock
muffler... I later welded the internal wastegate shut and
install an external HKS Racing series wastegate.

Matt
This is really the best way to solve boost creep, internal gates suck!
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Old 03-09-2003, 10:10 AM   #10
Tuning Factory Inc.
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Quote:
Originally posted by mattjk
Not true, dp is not causing the problem, I have a TXS
downpipe with no cats and I'm getting boost creep
with my VF22. A free'r flowing exhaust is just going to
make the problem worse. The internal wastegate port
being too small on the IHI turbos is the problem.

My boost creep goes from 10.5psi up to 13.3psi
at 6500rpm. This is with no boost controller at all,
the solenoid is connected directly to the turbo outlet
nipple.

This sucks because my goal was to run only 12psi...
I guess I'll have to get a re-flash and bigger injectors.

As a side note, I started getting boost creep when I
change my 2.5" rear muffler to a full 3".

Matt
Yep I've noticed this on a few setups. Perhaps porting the stock wastegate will help a little.
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Old 03-09-2003, 10:50 AM   #11
Austin
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I used to creep up to about 21psi between 5-6000 RPM with a straight hose from the turbo outlet nipple to the wastegate actuator. After mildly porting the wastegate, my creep is down to about 17psi at 7300rpm. I can live with that.

First, remove the circlip attaching the wastegate actuator rod to the flapper arm.


For my VF34, the flapper door is 1.221" in diameter. The non-modified wastegate hole diameter is .986". Assuming I wanted to keep a .050" lip for the flapper door to sit on and seal, that gave me .134" to work with.


Remove the 10mm nut securing the clamp, then remove the clamp securing the exhuast housing.


Instead of allowing the exhaust housing to fall, I tapped around it lightly until I could slightly move it with my hand, then gently wiggled it off the rest of the way. You don't want the housing to touch the blades on the turbine wheel.


No need to worry about marking the exhaust housing or center section before you remove the exhaust housing - there is a small roll pin in the bottom of the center section to align the exhaust housing when you re-install it.

Last edited by Austin; 01-18-2004 at 05:29 PM.
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Old 03-09-2003, 10:51 AM   #12
Austin
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The unmolested wastegate opening. You can see how much area we have to work with by the shiny portion of the sealing surface.


My final hole ID was 1.078". I removed .092" of material from the lip - about 2/3rds of what I could've removed. In my case, the flapper door didn't sit exactly centered on the opening - it sat a bit toward the outside (toward the pivot point) - so I concentrated more on that side of the hole.

There is considerable room for improvement besides simply making the opening larger. I rounded all corners and edges inside, and removed all flow trips to make a very low resistance path for gasses to flow through the wastegate.









Last edited by Austin; 01-18-2004 at 05:30 PM.
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Old 03-09-2003, 11:29 AM   #13
mattjk
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Quote:
Originally posted by Austin
The unmolested wastegate opening. You can see how much area we have to work with by the shiny portion of the sealing surface.

My final hole ID was 1.078". I removed .092" of material from the lip - about 2/3rds of what I could've removed. In my case, the flapper door didn't sit exactly centered on the opening - it sat a bit toward the outside (toward the pivot point) - so I concentrated more on that side of the hole.

There is considerable room for improvement besides simply making the opening larger. I rounded all corners and edges inside, and removed all flow trips to make a very low resistance path for gasses to flow through the wastegate.
Nice post, d00!!!
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Old 03-09-2003, 04:11 PM   #14
teiva-boy
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Austin you have a pair of HUGE ones to pull apart your own VF34 and start grinding away. That is something I wouldn't try... Way to go!
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Old 03-09-2003, 08:19 PM   #15
Austin
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It's really not difficult at all - I was just scared I'd go too far and screw up the flapper door sealing surface.
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Old 03-09-2003, 08:27 PM   #16
mattjk
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Yep, it's pretty easy to remove the housing, unless you have
thousands of miles on the turbo and it's fused together...
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Old 03-20-2003, 01:58 PM   #17
Red Rocket
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Thanks for doing a writeup, Austin. I did my VF29 back in early Feb (I think I was the first! ), but haven't tested it beyond 2nd gear with my cutout open. But by all indications it should be working for me.

Kevin
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Old 03-26-2003, 11:55 AM   #18
Austin
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Then get out and test it!
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Old 05-02-2003, 03:02 PM   #19
RiftsWRX
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Ahhhh... I needed this post...

Jorge (RiftsWRX)
www.ProjectWRX.com
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Old 05-02-2003, 07:40 PM   #20
silvercharged
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I have found a simpler solution to the boost creep problem when using a MBC.

It involves using an industrial micro pressure relief valve just prior to your MBC.
You are getting boost creep because the waste gate is starting to open ever so slightly before the target boost you've dialed in has been reached

Example: Say you've dialed in 15 psi on your MBC......At 6 psi it's already starting to open, and by 12 psi, it's really starting to open, until you reach full open at your setting of 15 psi.

With a micro pressure relief valve plumbed just prior to the MBC, this valve will positively prevent ANY pressure from getting to the MBC or wastegate, thus eliminating boost creep. When the pressure approaches your MBC target, the valve opens instantaneously and whoosh!, the full 15 lbs. goes to your MBC and the MBC regulates the pressure to allow the wastegate to open and vent the excess gases.


The other beauty to this is that you can adjust this valve so that your boost comes on as hard or as soft as you desire...

Using our example of a 15 psi target, if you dial the relief valve to "pop" at 14 psi, boost will come on incredibly fast... on the other hand, you could dial the relief valve to "pop "at say 10 psi, there by eliminating most of the creep, but still have a smoother boost build up to the target..

Keep in mind that the pressure dialed into the relief valve must not exceed what your MBC is dialed in at, to prevent overboost....

Any thoughts, comments, hate mail, appreciated......
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Old 05-02-2003, 08:12 PM   #21
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Quote:
Originally posted by silvercharged
It involves using an industrial micro pressure relief valve just prior to your MBC.
Congratulations, you've just created a type of dual stage MBC... But it won't do anything for boost creep.

Boost creep is when, even running a straight line from the compressor outlet nipple/pressure source to the wastegate actuator, boost level creeps up. Some amount of boost creep is okay, but too much can be a problem.

With an 8 pound wastegate spring, a car running a straight line from the compressor outlet nipple to the wastegate actuator should run 8psi boost pressure. Boost creep causes that car to build more than 8psi boost pressure - it's when the wastegate is unable to physically flow enough gas to limit the flow through the turbine wheel, causing excessive flow through the turbine wheel, causing the turbo to spin faster than intended.

If your car (with a straight line to the wastegate actuator) creeps to 12psi, but you intend to run 16psi, then it's not a problem for you... but no form of boost control will enable you to run <12psi.

If your car boost creeps to, say, 21psi when you intend to run 16psi... then it's a problem.
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Old 05-02-2003, 08:23 PM   #22
silvercharged
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OK Austin, I see what you're saying, the difference being each other's definition of boost creep.....
Mine being when the wastegate opens prematurely before reaching a predetermined boost setting.....

My bad..
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Old 05-08-2003, 01:33 AM   #23
Akiata
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Ok, I had boost creep after I put on a Vishnu signature series exhaust w/ cat (last week) with a VF29 (have had this for awhile w/ stock turbo back). It would creep to appx 18 when I had my boost controler set to appx 12. After reading this thread I was inspired to port my wastegate. I didn't remove the turbine housing like Austin did but I do have access to high pressure nitrogen (2000 psi) so I blew out all of the shavings. My wastegate was also offset like Austin's so I did most of the grinding the same way he did.

And the result.... no more boost creep!!! I will have to do some more runs later or in a less populated area but I got on it in 3rd gear to redline and it *might* go up 1 psi but that is ok by me.

So the moral of the story is if you have an IHI VF turbo and you are putting on a turbo back exhaust you will need to port the wastegate at the same time.

p@
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Old 05-31-2003, 10:56 PM   #24
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Default VF24 ported today! :)

My VF24 was creeping from 15 to 18.8PSI.
I ported the wastegate , same deal, more towards the flapper pivit, also severly rounded the passage into the wastegate.
No more boost creep! Although I did have to raise the boost numbers in my utec (which were VERY low anyway) to get the same boost.

I love it and HIGHLY recommend that ANYONE installing a VF turbo, port the wastegate BEFORE you install the turbo. You will be glad you did.
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Old 11-03-2003, 03:35 PM   #25
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very informative.
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