Hello all. I have a bone stock y7 with a Delta 272 cam and hmt turbo kit (consisting of a ported hf mani, T3/TO4E turbo, 2.5" downpipe, open exhaust, 38mm wastegate, Grainger style mbc, 2.5" charge pipes, 1st gen dsm bov, 28x6x3" intercooler, dsm 450cc injectors, z6 throttle body and intake manifold all tuned with TurboEdit/BRE). Here's some pics....



I have a 3.83 psi spring in my wastegate. My deal is this. I hit 4 psi and boost will hold until 6500 rpm where boost will spike past 15 psi. I tighten up the mbc and I can adjust my boost pressure correctly, that is up to 6500 rpm where boost spikes again past 15 psi. Each and everytime I get the same results.

As you can see I have my wastegate venting spent gases through the oem wastegate hole. In these particular pics the gate tube is quite long and I have cut the length down quite a bit. I will post more recent pics later.

Is the small diameter of the gate hole creating my boost spike? I'm no engineer so I can't figure this out myself. Any advice would be much appreciated



Modified by turbo1.5 at 2:52 PM 1/15/2008

 

not much of a sigle cam man myself but should you even be reving that out to 6500 or more

 

Your wastegate dump looks fine.
Has the setup ever worked right before, or did you just put it together?

 

sohc's usually redline 6800-7000 usually...shifting before 65 just to prevent a boost spike would be kinda annoying to me. I could be totally wrong, but it sounds like a wastegate problem?

 

This may seem strange, but what is the A/R of the housings, and trim of wheels? I am thinking also your WG might have something to do with it; try shimming under the spring without the MBC to see if you can get more of a favorable result;

are you hearing the WG open? (should be obvious from inside the car when driving)

 

In my opinion, the wastegate is not flowing enough for your setup. For the amount of psi you are running and your wastegate placement, you need to run a bigger wastegate. See you are trying to release ALOT of unwanted exhaust and the small diameter of the gate just is not cutting it at those rpm's. If you were running more psi then it would not be so much of a problem. Im suprised you dont have more problems down low.

Where is the wasegate getting the boost signal from?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by postman &raquo;</TD></TR><TR><TD CLASS="quote">not much of a sigle cam man myself but should you even be reving that out to 6500 or more</TD></TR></TABLE>
I can rev to 8k with the Delta 272 regrind. With the stock cam I would run out after 6000 rpm
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bigb16 &raquo;</TD></TR><TR><TD CLASS="quote">Your wastegate dump looks fine.
Has the setup ever worked right before, or did you just put it together?</TD></TR></TABLE>
Yes I made this last week
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EASY101 &raquo;</TD></TR><TR><TD CLASS="quote">sohc's usually redline 6800-7000 usually...shifting before 65 just to prevent a boost spike would be kinda annoying to me. I could be totally wrong, but it sounds like a wastegate problem? </TD></TR></TABLE>
The wastegate is brand new. I have taken it apart several times and there are no rips in the diaphragm
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JaredKaragen &raquo;</TD></TR><TR><TD CLASS="quote">This may seem strange, but what is the A/R of the housings, and trim of wheels? I am thinking also your WG might have something to do with it; try shimming under the spring without the MBC to see if you can get more of a favorable result;

are you hearing the WG open? (should be obvious from inside the car when driving)</TD></TR></TABLE>
I have the open downpipe so I cannot really hear an audible change in tone. I will try shimming the spring to see what happens
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mitsuman &raquo;</TD></TR><TR><TD CLASS="quote">In my opinion, the wastegate is not flowing enough for your setup. For the amount of psi you are running and your wastegate placement, you need to run a bigger wastegate. See you are trying to release ALOT of unwanted exhaust and the small diameter of the gate just is not cutting it at those rpm's. If you were running more psi then it would not be so much of a problem. Im suprised you dont have more problems down low.

Where is the wasegate getting the boost signal from?
</TD></TR></TABLE>
This is what I was thinking. The opening on the turbo is only .812" while my wastegate is 1.5". I bet if I can open that up to a solid 1" opening I bet that would make a difference.

I have a line going from the compressor housing, through the mbc then to the bottom port on the wastegate

Let's talk about my downpipe. It consists of a 2.5" 90 bend and a 2.5" 45 bend. It probably 12" in length. Do you think my exhaust being so open would allow this to happen? These old turbo bastards around me seem to think so

 

Might wanna throw another bolt in that tranny!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tippyman &raquo;</TD></TR><TR><TD CLASS="quote">Might wanna throw another bolt in that tranny!</TD></TR></TABLE>
I would if I could get the broken bolt out

 

We have done this setup before.... actually I'm 99% you contacted me before. Open up the downpipe flange hole more and you should be fine. Make sure you are using the biggest piece of pipe that you can as well. When we did this we used sch10 1.5. Are you using something smaller.

 

Whats going on dude.
1493cc from TurboD16.

Personally Id say open the WG hole on the turbo, and run your vacuum/boost source from your I/M to your WG.

 

by the sounds of it, your having boost creep issues, not spiking.

edit: i would take the mbc off

 

Looks and sounds like its just your xspower wastegate. I and others have found this issue with them:

Find an air compressor, turn it way down, then pressurize the WG. More than likely your WG spring is binding inside, meaning its not opening up nearly as much as it should. If you give it 20psi, it opens a lot, then you can push it open further with your finger, its binding. You need to heavily sand the OD of the spring and the ID of the 'cap'. That WG port is in a spot where you get the highest pressures, meaning it would push the WG valve open TOO far if anything.

I'm assuming you've tried it w/o the MBC? It could also be the MBC not flowing enough, which wouldn't open the WG enough. Try enlarging the area behind the ball bearing (around the spring) so more air can move around the ball.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RCautoworks &raquo;</TD></TR><TR><TD CLASS="quote">We have done this setup before.... actually I'm 99% you contacted me before. Open up the downpipe flange hole more and you should be fine. Make sure you are using the biggest piece of pipe that you can as well. When we did this we used sch10 1.5. Are you using something smaller.</TD></TR></TABLE>
Yes I did contact you before about this. I wouldn't have done this if you hadn't shown me that pic! I am using 1.5" OD pipe but the hole in the flange is .850". I'll buy a larger bit today so I can open it up to at least 1.25" inches
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dr. D-Series &raquo;</TD></TR><TR><TD CLASS="quote">Whats going on dude.
1493cc from TurboD16.

Personally Id say open the WG hole on the turbo, and run your vacuum/boost source from your I/M to your WG.</TD></TR></TABLE>
I saw that's how you have your's ran but I wasn't sure how vacuum would affect/not affect the bottom port. I'll try that too
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ekhonda87 &raquo;</TD></TR><TR><TD CLASS="quote">by the sounds of it, your having boost creep issues, not spiking.

edit: i would take the mbc off</TD></TR></TABLE>
The spike is present whether the mbc is connected or not. I can adjust my boost pressure with the mbc it just seems to spike after a certain rpm no matter what
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HiProfile &raquo;</TD></TR><TR><TD CLASS="quote">Looks and sounds like its just your xspower wastegate. I and others have found this issue with them:

Find an air compressor, turn it way down, then pressurize the WG. More than likely your WG spring is binding inside, meaning its not opening up nearly as much as it should. If you give it 20psi, it opens a lot, then you can push it open further with your finger, its binding. You need to heavily sand the OD of the spring and the ID of the 'cap'. That WG port is in a spot where you get the highest pressures, meaning it would push the WG valve open TOO far if anything.

I'm assuming you've tried it w/o the MBC? It could also be the MBC not flowing enough, which wouldn't open the WG enough. Try enlarging the area behind the ball bearing (around the spring) so more air can move around the ball.</TD></TR></TABLE>
I have not tried pressuring the bottom port to see how far the psiton will travel. I will try that out as well. Assuming I have the 4 psi spring I imagine the spring/valve should move quite a bit. We'll see what happens.

I really don't think the mbc is the issue. With a line straight from the compressor to the bottom port I still get boost spike.

Here's some pics....





and the top portion of the wastegate...


Flame on

 

just a question because I'm still learning myself...in that last picture, your seal/gasket looks compromised (cracked and distorted a little) would that have anything to do with the issue?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EASY101 &raquo;</TD></TR><TR><TD CLASS="quote">just a question because I'm still learning myself...in that last picture, your seal/gasket looks compromised (cracked and distorted a little) would that have anything to do with the issue?</TD></TR></TABLE>
It looks that way, but the silver is just paint that somehow got on there. There are the two spots that looked a bit pinched but is seems to be how the material creased when folded. There are no leaks/holes or puntures.

I also plan on testing a Tial wastegate this weekend to see if my chinese wastegate is the problem. I'll post the updates

 

Thanks for all of the help and advice. It seems a lot of DSM tuners face this issue with upgraded turbos. Taking a cue from them this weekend I plan on taking my turbine housing off and porting it as well as the hole I have in the 5 bolt flange.

I will also try the different things you all suggested in case the porting doesn't cure it. Thanks again!

 

I put money on that housing needing to be ported.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbo1.5 &raquo;</TD></TR><TR><TD CLASS="quote">
Yes I did contact you before about this. I wouldn't have done this if you hadn't shown me that pic! I am using 1.5" OD pipe but the hole in the flange is .850". I'll buy a larger bit today so I can open it up to at least 1.25" inches
</TD></TR></TABLE>

That hole needs to be bigger, air can't flow out of that tiny hole. Chamfer the edges as well to help the air go out.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by agrn93ls &raquo;</TD></TR><TR><TD CLASS="quote">I put money on that housing needing to be ported.</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RCautoworks &raquo;</TD></TR><TR><TD CLASS="quote">

That hole needs to be bigger, air can't flow out of that tiny hole. Chamfer the edges as well to help the air go out. </TD></TR></TABLE>
I agree with both of you. I will port it out this weekend and let you know how it goes!

 

how much pressure are you pushing? I would guess that since there is a flow bottleneck before the WG this is causing your surge; see what you can do about opening up the hole in the turbo; my best opinion....

cause your having air getting pushed through, then when the WG opens, it creates a strange pressure differential that the WG has trouble reacting with; a delay that is making it ineffective... once again, best guess

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JaredKaragen &raquo;</TD></TR><TR><TD CLASS="quote">how much pressure are you pushing? I would guess that since there is a flow bottleneck before the WG this is causing your surge; see what you can do about opening up the hole in the turbo; my best opinion....

cause your having air getting pushed through, then when the WG opens, it creates a strange pressure differential that the WG has trouble reacting with; a delay that is making it ineffective... once again, best guess </TD></TR></TABLE>
Your guess is as good as mine lol. I'll post the porting results/pics when I finish!