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Discussion Starter #1 (Edited)
I finally hit the rollers on Monday. Ambient temps in the shop at the time were 96.81* F. Not the most ideal conditions but anyways, onto #'s and pics/vid then my issues.

Final numbers at the end of the day were 397hp/453tq on 9psi. Timing is under 13* until 4K rpm, then ramps up to 16* at redline. My tuner was trying to keep the torque under control and wanted a nice safe tune on such a hot day.

Here's a scan of my dyno sheet and a short vid for now.




Now for my issue.

The initial pull to see where the waste gate was going to run at hit 8psi. After tweeking the tune she made 360/445 on 8psi. We adjusted my turbosmart MBC 1 click to see what the adjustments would regester and hit 8.29psi. So we hit it with 3 more clicks and made 9psi and the numbers stated. The problem arose when we tried 3 more clicks on the MBC and got nothing. After 2 pulls there we tried another 2 clicks and were still at 9psi. That's a total of 5 clicks over the 1st 9psi setting but we got no increase in boost.

I have my MBC hooked up like this, per turbosmart's site. Although my boost source is from my plenum (yes I know).



A member on another forum had suggested to try installing it like this.



I'm still learning my way around turbos, so any help will be greatly appreciated. I'm going to check all cold side clamps for possible leaks.

Another issue we had is it drops boost up top. If you look at the boost graph, it drops after 5K rpm. It fell from 9psi at 5K to 7.8psi at end of pull.
I'm going to try a pull without the air filter to see if that any kind of restriction.

Other than that the car is fun as hell. Plus seeing I didn't reach what I wanted it just means that my journey continues.
 

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Sounds like you have a boost leak. Go over all your connection again including your bov. If you have a small hand vacuum pump remove bov and make sure it's not leaking. I had my brand new on3 bov leak like a sive.
 

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You have the mbc hooked up correctly. Cant make out the second pic but don't think you to see pressure on the top port of the wg unless using co2 kit or something.

What turbo and ar? could be seeing back pressure causing the spring to open. Could also be a weak wg spring.
 

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Discussion Starter #4
I'm running an On3 70mm w/.68 ar. Seems like I should have reached my 10-12psi goal easily.

I'll check the cold side clamps on my day off. As far as the BOV test do you mean like a leakdown test? Put pressure to the port and make sure it holds steady? Sorry if that sounds noobish. :idunno:
 

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could it be that the load on the engine dropped off up top due to the 3.73 gears which in turn caused the boost to drop off?
 

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My MBC is hooked up like the second pic. and works well like that. But I get the pressure from the compressor instead of the intake.
 

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First thing you need to do is check ALL of your couplers with a wrench and make sure that they are tight and sealed properly. EACH ONE. Also make sure that your vacuum lines aren't faulty anywhere. (melted???)

Second step take off whatever air filter you have, and test it without it completely. (you would be surprised how many times i've seen this happen) usually followed by I just paid 80 bucks for that.

third step would be checking your hardware. Pressure test the intercooler if possible and make sure it's not leaking. I've seen that before.

4th step, come back here and tell us you figured it out.
 

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Discussion Starter #9
Thanks for the ideas guys.

Vacuum lines are all new. WG and BOV both have dedicated source ports. I put another vac port in my EGR block-off plate for FRPS and boost/vac gauge.

Cold side couplers and a run sans air filter I can do on Firday.

I'll let you know what I find out in a few days.
 

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I'm running an On3 70mm w/.68 ar. Seems like I should have reached my 10-12psi goal easily.

I'll check the cold side clamps on my day off. As far as the BOV test do you mean like a leakdown test? Put pressure to the port and make sure it holds steady? Sorry if that sounds noobish. :idunno:
Yes that's the way I did mine
 

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Discussion Starter #11
Thanks Sonic, I try and give that a testing tomorrow too.
 

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When my boost dropped off it was the wastegate that was leaking.

Put compressed air to the vacuum line running to wastegate to check it for leaks.
 

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Discussion Starter #14
Yeah, last week was killer hot. Temps in my garage were over 110*F, I ain't workin' in that ####. :hammer:

I'm off this weekend so I'll see what I can get figured out.

Is there anything that can be used on the cold side couplers to help seal them around the piping besides just the clamps?
 

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Hair spray will help it seal and help keep it from blowing off.
 
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