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Old 10-23-2012, 03:01 AM   #1
VNT IC Upgrade Q's  
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Has anyone replaced their stock VNT intercooler with a higher flowing unit, on an otherwise completely stock VNT setup? I am curious to hear the results achieved. Thanks
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Old 10-25-2012, 03:51 AM   #2
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Anybody??? I am curious as to what happened boost wise when switching out to a higher flow IC on an otherwise stock setup? Small increase in boost? Overboost problems? Someone has to have done this...
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Old 10-25-2012, 06:05 AM   #3
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I have not done this but....
Increasing the size of the intercooler alone will probably not allow more air into the engine.
You still have the same size TB and a Bottleneck at the Intake.
You also need to be able to get the exhaust out quickly to be able to get more air in...
Changing to a larger exhaust or flow thru muffler will lower the backpressure in the exhaust system and cause boost creep/overboost issues, the turbine side will overspool and become uncontrollable.
Chrysler designed the exhaust with enough backpressure to be part of the boost control system.

I know about the boost creep from personal experience.
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Old 10-25-2012, 06:49 PM   #4
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I have the Dynomax cat-back exhaust system on my car. But it didn't change the boost much at all(maybe 1 psi when it's cold out), so I am pretty sure the back pressure on the super turbo muffler is pretty close to the stock muffler. The flow must have increased just a little. Anyway, I know that the pressure drop is high in the VNT IC's. Do you know what it is at stock boost level? I would think that a larger FMIC would definitely get the charge cooler which is always good(especially at low speeds which the VNT IC is no good for). But I am wondering just how related the stock IC is to the boost control on the VNT's. 1. If you install an IC with a much lower pressure drop does the boost level at the plenum increase? -Or- 2. It just takes some strain off of the turbo and causes less resistance for the compressor resulting in lower wheel speeds? In my mind I would lean towards the second scenario because the exhaust side/design of the VNT turbo is the primary method of boost control, obviously using the vacuum actuated vane controller. I have been building and racing the TD's for years, I just have never owned a VNT, up until a year ago.
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Old 10-25-2012, 06:54 PM   #5
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The VNT ic is known to be very restrictive. Same IC as the T3's use. By dropping the restriction it will cause the turbo to not have to run as fast to make the same boost in the intake. What this will do on a VNT car I'm not sure. But on a regular turbo you'll gain more flow on the exhaust side as well.
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Old 10-26-2012, 03:15 AM   #6
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The VNT ic is known to be very restrictive. Same IC as the T3's use. By dropping the restriction it will cause the turbo to not have to run as fast to make the same boost in the intake. What this will do on a VNT car I'm not sure. But on a regular turbo you'll gain more flow on the exhaust side as well.
This is what I am unsure about, too. I guess if nobody on here has tried this than I will just have to be the first and report back on what I find. Stock VNT car + upgraded FMIC = . I'll find out.
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Old 10-27-2012, 02:50 AM   #7
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Okay so I found some old threads on here after digging a bit. It's funny how just variations of basically the same search words will bring different results. People have claimed that changing out the intercooler does not cause boost creep or over boost issues. And, like we already know, the boost issues reported were when exhaust changes were made. One guy on here, "soupcan", said that the best thing he thinks he ever did for his VNT was upgrade the intercooler. I will report back when I get mine completed. I told myself I was going to keep my car COMPLETELY stock. I do like popping the hood for the purists and having them say it looks like the power plant did the day it rolled off the assembly line. Of course, I will make sure I keep every stock part I remove for if/when I go back to stock.
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Old 10-27-2012, 04:54 AM   #8
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Everybody says they did this and that with their stock VNT and with no boost creep issues, Talk is
Cheap.
I own one(since new) that was fine before a muffler only change so I call BS and say Prove It.

Doubting Thomas here wants to see the Video and Timeslip from the Track when you are done showing no boost creep occurred, be sure you wind out each gear to at least 5500 and run thru the stripe in 3rd, on the street does not count.

Be sure to post the temp, humidity and adjusted altitude, hot temps and above sea level does not count either.
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Old 10-27-2012, 05:08 AM   #9
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I never said that there will be no boost creep from an IC swap. I have never done it that's why I started this thread. I said that people on this forum in other threads claimed that they didn't get boost creep and overboost from upgrading the intercooler, Thomas.
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Old 10-27-2012, 09:30 AM   #10
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Good to hear some others have done it. My thoughts have always been that the VNT will like a free-flowing intake side. It'd be interesting to see if you took that to the max with a 3" id intake to the turbo with something like this. 100_0136 And then 2.5" i/c lines, a good ic like it sounds like you have, and a 2 piece if you could then do anything to the exhaust side of the mix and still have the car control boost.
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Old 10-27-2012, 06:27 PM   #11
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Everybody says they did this and that with their stock VNT and with no boost creep issues, Talk is
Cheap.
I own one(since new) that was fine before a muffler only change so I call BS and say Prove It.

Doubting Thomas here wants to see the Video and Timeslip from the Track when you are done showing no boost creep occurred, be sure you wind out each gear to at least 5500 and run thru the stripe in 3rd, on the street does not count.

Be sure to post the temp, humidity and adjusted altitude, hot temps and above sea level does not count either.
I'll install it. If it over boosts, I'll mention, if not, I'll mention it.
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Old 10-27-2012, 07:06 PM   #12
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why do use 2 bov? GLHNSLHT2
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Old 10-27-2012, 09:31 PM   #13
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why do use 2 bov? GLHNSLHT2
because I gave him crap about sticking it in the feed line. So listening to both people on where to stick the things and stick them in both lines lol
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Old 10-27-2012, 09:39 PM   #14
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well on the IC issue.

First when you lower your drive pressure by lowering your pressure differental you get more boost gage PSI without pushing the turbine so hard.

This is something people with the SRT 4 notice hugely, big FMIC and no boost loss on top end caused by drive pressure opening the WG flap.

The VNT though creeps with too much drive pressure, and no where for it to go. So logically less drive pressure from a better IC will allow more boost and flow without creep.

The 13 second VNT CSX out there is running a better flowing IC, there is a good chance this is the main piece that allows it. The stock IC like the T3 engines got is horrid and really ups the drive pressure, putting strain on the tiny VNT turbine.

I think I would try a water to air unit tucked in close to the engine. Decrease fill volume and greatly lower drive pressure for the same boost.

In NAJ case, I would install a S60 IC as I know he wants to stay basically stock looking. If I still had mine I'd lone it to you NAJ but some one bought it lol. Maybe we can get GLHNSLHT2s IC from him lol.
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Old 10-28-2012, 12:06 AM   #15
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why do use 2 bov? GLHNSLHT2
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because I gave him crap about sticking it in the feed line. So listening to both people on where to stick the things and stick them in both lines lol
no no no, It's because when I had one talon BOV I was driving around a lake road with no hood for some reason or another, can't remember why. But anyway while racing around this tight twisty lake road I could get the turbo surge every once in a while. So one Talon BOV doesn't flow enough. Easy enough 2 should be good :)

Quelling the argument of which hose to put it in was only a side benefit :)
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