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Discussion Starter · #1 ·
I figured I would start a thread to help the endless stream of guys who are asking questions basic about these devices (either in tandom or by themselves)

To control the boost in your SRT your need a "wga" waste gate actuator (to move the turbo wastegate) and a boost controller in one form or another be it PCM, electronic aftermarket, manual or bleed/bleed tee. Remember the turbo will literally spin itself out of control in a self perpetuating cycle without boost control. And boost control is gained by use of boost itself.

The waste gate actuator holds the wastegate shut by virtue of a spring/spring tension. This spring can be provided and in turn purchased at different rates ie: 4 psi, 7, psi, 14 psi, etc. The waste gate when installed in a relaxed arm position (no pre tension of the spring) will maintain the wastegate closed until the boost pressure equals or surpases the rated spring pressure.

Pre-tension or "tunning" the wga by adjusting the actuator arm length in effect changes the spring rate (making the spring "stronger") and will hold the waste gate closed at even higher presssures (with no real limit which can be dangerous).

The wga has a diaphragm side which is pressurized by the turbo boost pressure (via the "green line" blue line" black line" etc) which when it reaches a high enough pressure will overide the force of the wga spring (assuming the spring is of a correct range and the wga is not over-tensioned) and force the wga arm to move and in turn open the wastegate.

A boost controller determines at what pressure and or how much pressure is allowed to flow to the wga diaph and cause it to move or start to move open.

Your SRT4 PCM/ECU is an electronic boost controller in and of itself and a damn fine one at that. It commands soleniod#2 by electrical signal to modulate open and pulse boost pressure flow to the wga on a graduated scale in response the relative position on the "boost table". The PCM will use boost to control boost.

A manual boost controller will accomplish boost control in a similar fashion, except it normally reduces the pressure that flows through it thereby artificially creating a reduced boost pressure being passed along to the wga. For example you may be actually boosting at 15 psi, but the manual boost controller is set to only pass 10 psi along to the wga, so its 12psi spring is not moved by the 10 psi, all the while its actually boosting at 15 and would normally be coming open by then. Of course a mbc is an all or nothing proposition and does not offer any graduated control based upon gear/rpm. Electronic boost controllers are required to accomplish this type of control.

A manual bleed also accomplishes the same thing as a MBC its just not easily adjustable. The bleed tee simply lets some of the boost preesure to escape to atmosphere so an artifically high boost pressure is required to actually move the wga arm (its like trying to blow up a ballon with a hole in it)

Running a aftermarket wga without a bleed, mbc, or keeping it on the stock pcm is very primative and counter productive. The pressure line you run to your wga is always going to be "on" or "fully pressurized" with whatever the boost pressure happens to be at the moment and affords no adjustment whats so ever. The diaph will always be charged and attempting to move the spring constantly. Its actually the safest way and will provide control, but its far less affective than even the stock arrangement.

Running a aftermarket wga with to large of a bleed or a boost controller set to aggresively can be very dangerous and even wreck your engine because the appropriate motive force is not being sent to the wga diaph. Over adjusting your wga arm can create dangerous levels of pretension requiring far to much boost pressure/force to open.

I offer this "primative" explanation in order to help some of the new guys gain an understanding of whats going on with their wga/boost controller mods

Any and all comments/clarifications are completely welcome and evn encouraged.

I have attempted to explan things in "simple" terms so please keep that in mind. I realize ceratin mechanics have been omited/simplified.

In closing remember YOU USE BOOST PRESSURE TO CONTROL BOOST PRESSURE via the wga. Its as simple as that :thumbsup:
 

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good write up. i always see people using a wga with no boost controller. one guy who made that post earlier said he was boosting 18 psi with no boost controller! Thats when your flapper arm on the manifold will bend like a wet noodle. I learned that from experience.
 

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Everything is very well explained except I would add one thing. Turbine backpressure also has an affect on when the flapper arm opens. Great writeup.
 

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Romans8:28 said:
I figured I would start a thread to help the endless stream of guys who are asking questions basic about these devices (either in tandom or by themselves)
Ha! Good luck with that...




The only addition I would make is that a bleed CAN be easily adjustable. A lot of electronic or factory boost controllers use solenoids as bleeds, and you can set up a MBC as a bleed, if you want. All you're doing is adjusting how much air bleeds off.
 

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Discussion Starter · #5 ·
Thanks for all the good comments guys, I concurr with whats been added. I struggled with exactly what all to say (and not to say LOL).


Maybe as other add onto the thread we will have a good reference for the srt4 community :thumbsup:

Sometimes the basics can go a long way in helping alot of people out :hi:
 

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With a WGA you get PTB what is a safe/ cheap way to have enough fuel? I know with PTB your EGT's go way up and can hurt the car... what do you need to boost safely? and are the EGT's guages that you can buy accurate?
 

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I could really use some help with some problems I'm having. The symptoms sound similar to boost issues you covered in your writeup.

For almost 2 months my Stage was working perfectly. Great boost, great accelleration, and the toys were all working as specified. Then over the course of a few days, things started to deteriorate. My car started boosting above the 20 mark and the dial-a-boost levels I had become used to changed. Where setting 0 was originally 9-10 PSI, it was now 14-15. Setting '1' had also raised to 18-20 where it was originally 15-16. Setting '2' or '3' were spiking past 20 and the needle fluctuated something fierce.

Pretty soon, none of my settings were working and to put it simply, I had to be careful with my right foot. WOT would shoot the needle straight down. (25+ PSI?) Also I had the trouble where my pink line on the WGA would pop off. I finally got that held down tight and upon the next spike I had another hose pop off and I lost much of my braking.

I have since changed back to the original Wastegate thinking that was the problem. It no longer boosts past 18, which I assume is because the stock one isn't strong enough.

I'm at a loss for what to check next. Calls to the Mopar helpline haven't helped and I haven't had time to take it to the dealer, I need the car as a daily driver.
 

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gtup said:
With a WGA you get PTB what is a safe/ cheap way to have enough fuel? I know with PTB your EGT's go way up and can hurt the car... what do you need to boost safely? and are the EGT's guages that you can buy accurate?
The other thread you started you were told to get fuel management, and you mentioned the power paq and e-manage. What is wrong with those two?
 

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somebody said that powerpaq wouldnt help.... or is that false? Will the PP help make safe A/F and EGT's?
 

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gtup said:
somebody said that powerpaq wouldnt help.... or is that false? Will the PP help make safe A/F and EGT's?
Yes it will! look in the psi-fi section they explain how they add fuel and take away fuel in every situation.
 

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sooo... If I have Stage 1 and put on a TCC WGA w/ #16 spring in it... I should, at the very least, run a MBC? or will Stage 1 be sufficient to eefectively control boost?
 

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Its wierd sometimes people would rather to use the WGA and no MBC to run the car and there happy...hell I tried using a TXS MBC and had terrible results
 

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Discussion Starter · #14 ·
shosterman said:
I could really use some help with some problems I'm having. The symptoms sound similar to boost issues you covered in your writeup.

For almost 2 months my Stage was working perfectly. Great boost, great accelleration, and the toys were all working as specified. Then over the course of a few days, things started to deteriorate. My car started boosting above the 20 mark and the dial-a-boost levels I had become used to changed. Where setting 0 was originally 9-10 PSI, it was now 14-15. Setting '1' had also raised to 18-20 where it was originally 15-16. Setting '2' or '3' were spiking past 20 and the needle fluctuated something fierce.

Pretty soon, none of my settings were working and to put it simply, I had to be careful with my right foot. WOT would shoot the needle straight down. (25+ PSI?) Also I had the trouble where my pink line on the WGA would pop off. I finally got that held down tight and upon the next spike I had another hose pop off and I lost much of my braking.

I have since changed back to the original Wastegate thinking that was the problem. It no longer boosts past 18, which I assume is because the stock one isn't strong enough.

I'm at a loss for what to check next. Calls to the Mopar helpline haven't helped and I haven't had time to take it to the dealer, I need the car as a daily driver.
It sounds like to me that little or even none of the boost pressure is actually reaching your wga. Perhaps a hose is broken, disconnected or leaking very badly. Trace down the pressure source from the wga back to your turbo and verify all the hoses are intact.
 

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Discussion Starter · #15 ·
Ultimateone said:
Its wierd sometimes people would rather to use the WGA and no MBC to run the car and there happy...hell I tried using a TXS MBC and had terrible results
Keeping it hooked up to the pcm control (solenoid #2) is much better than that approach. No MBC or bleed = a constant opening/attempted opening of the wastegate.

I would think a car with no MBC or bleed with the pcm bypassed would spool much slower than one setup correctly
 

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Well I first started with the green line when I first installed my AGP and for awhile it was nice, but the initial spikes were too much and it felt a little surgyish :D

I switched to the blue per what Nivo and Jean did originally and my car runs SO much better now. Its wierd...sometimes seems that every car is different...eventually I will get some sort of EBC.
 

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Ultimateone- So you are just running a WGA.... when you are driving normally do you always make sure your not getting PTB?
 

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I think it depends on the wga used using the agp which is adjustable is just like having a boost controller look at srt4gurl she ran just the agp with stage one, aftermarket bov and exhaust and had just as fast time at the track as with the boost controller. I do agree that a wga with mbc is much better then just the wga alone.
 

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gtup said:
Ultimateone- So you are just running a WGA.... when you are driving normally do you always make sure your not getting PTB?
I suppose so..the only thing I dont like is flutter when on the gas....Its said to be normal but to me it doesnt seem right.
 

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wga is fine... but EBC make it so u can fine tune quicker and easier.. if you boostin 16psi with wga or mbc or ebc won't make no difference.. 16 is 16... (supposely ebc hold boost better)
 
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