Does anyone know the size (pitch, thread, NTP?) of the wastegate command valve on a stock turbo from a generation 3? I want to find a plug for it as we're putting the turbo on a gen 2.

 

I can't remember for sure but a oil drain plug is the same from auto parts store.
I saw a post maybe M18-1.25

 

oil drail plug from a 2nd gen will fit, it can be modified easily. there is a small hole in the that MUST be plugged off, if installing on a 2nd gen there are a couple things you need to do. I'll post a link to my thread, its in ABdiesel, you might not be able to see the pics unless you register (its free)

http://abdiesels.com/forum/index.php...=1&#entry34847


here are some pics of my swap

 

Thanks for the info Nick. I wish I had seen your install before we did ours because I was running back and forth to town for parts - the worst of which was a new v-band flange (4.5 inch) for the downpipe (MBRP) supplied us one that had a 4" flange.

I was wondering about that little hole where the solenoid goes so I looked it up in my Dodge Ram Service Manual. My understanding is that when current is passed to the solenoid (under high load), it prevents flow through that little hole, which increases the boost of the turbo.

We didn't plug that little hole, so my assumption is that the turbo is not boosting as much...?

 

here is a better way to do it.
if you look at the solenoid there are three ports on it separated by two o rings the hole in the end is manifold pressure. the center is to the waste gate. the waste gate spring is set to 20 psi. now look at the portion that has the threads. you will see four holes. this leads back to the intake. inside the solenoid there is a cup with a spring that when no voltages is applied it covers the 4 hole port setting the waste gate opening at 20 psi. when the ecm calls for more air it sends a modulated 5 volt signal to the solenoid to increase opening to the required pressure up to a limit of 30 psi. this is for emissions. if you have excessive air you produce NO the ecm keeps the pressure just barely enough for combustion thus the smoke. i figured out two ways to make it work remove the three o rings to prevent damaging them and cut the solenoid into about 7/8 inch above the base that mates to the turbo next cut the square part where the wrench go's deeper to make it easier to tighten up. i cut some more of the outer barrel off for looks but you do not have to. next remove any parts left in the center tube, you will be able to see all the way through the tube. tap the tube with a 1/8 in. npt. here starts the two different ways to do this, the first way is to install a 1/8 pipe plug with a hole drilled and tapped in the middle of it to accept a fine thread screw i think i used a 6-32, taper the end to a needle, screw a nut on and screw it in the plug. screw it in until it stops. you now have your needle valve set at minimum pressure, unscrew it a few turns and adjust to where you get 35 psi max. the second way requires brazing, braze the four ports closed and braze the tip of the high pressure tip closed and drill a smaller hole in it to limit the amount of air, next screw a needle valve in where the plug would have gone. take the rubber washer out of the valve and use a piece of copper wire in its place, you do not need a seal, this is only for resistance on the needle.

 

Hmm...the solenoid is on my 2006 Dodge with a Garrett turbo. I wonder if it even does all the same functions on my Garrett?

Now I get thinking of it, I'm not sure I want my dodge to have it either. A simple line to the wastegate actuator...wouldn't that be best? I mean, with all the mods done to the trucks does one want the computer messing with boost when the turbo is completely different, not to mention fueling?

 

you do not want the ecm to control turbo boost, that is why we mod the solenoid. the problem is the stock diaphgram is set for 20 psi. you can do several things one is to leave the solenoid in and block off the port from it, drill and tap the housing and install a adjustable boost elbow and set to 32 psi, mod the solenoid to adjustable like my pix or get a 32 psi diaphgram. do not use a plug like shown above. the ports for the solenoid return boost air to the volute to reduce pressure to the diaphgram, with the restriction removed huge amounts of boost is returned to the volute reducing compressor efficiency

 

I apologize in advance for my ignorance here, if I am missing something...I'm just trying to understand...

With the little experience I have had with car turbos (gas engines), the wastegate is pre-set to a certain PSI and gets its pressure from somewhere in the compressor stream of air. If one wants, he/she can set a max boost by shortening the actuator rod...and control boost from inside the car by installing a boost controller to restrict the boost going to the actuator (which is what this command valve sounds like it doing).

So on my 2006 w/Garrett turbo, can't I:

1. set the actuator to 40 PSI (the maximum the Garrett manual says it can handle safely)
2. block off every hole in the fitting where the command valve goes (braze them shut?)
3. put a "plug" in where the command valve goes, one that is pre-drilled and tapped
4. add a fitting to the new plug to connect this pressure hose to the actuator
3. keep the command valve connected electronically but tie it out of the way (so the computer sees it connected)
4. Potentially add an electronic boost controller in the boost line, if required, to manually control boost in the cab (although with diesel, I'm not sure what the point would be).

Why would there be a need for a fitting that has a bleed screw to set the boost when the wastegate is already doing that?

(I'm pulling off my Garrett stage 3 to change the turbine housing to a stage 2, so I have the opportunity to do other mods on the bench...)

 

several things i think your garrett is set to 20 psi to match stock you can place a 145 ohm resister across the truck plug and adjust the wastegate to 35 psi this would be the best for your garrett. i usually cut the plug off of the solenoid and solder the resistor on the leads and plug it in the truck.
you have to see how the holset solenoid and housing works for very fast acting on boost pressure to reduce NO it took us a day with one on a bench and a oscilliscope hooked to one in a truck to figure it out. on the stock turbo the wastegate is set to 20 psi when the ecm allows a little more boost it sends a modulated 5 volt signal to the solenoid. the very tip of the solenoid has a small hole in it where the boost pressure enters the wastegate is connected to the center section, with no voltage to it. the wastegate opens at 20 psi. when say 25 psi is called for a signal is sent slightly opening a third passage back to the volute. since the boost opening is small the pressure is held at 20 psi to the wastegate, as more boost is called for the solenoid opens up more where at 30 psi boost you have 20 psi on the wastegate. the turbo curve on the holset is different than the garrett. you should limit the stock turbo to 32 psi.

 

I get how it works but the question is why use it at all? Since the Garrett I have is very different than the stock, why give any control to the command valve? It doesnt harm the engine to over-supply air. And the device is just one more thing to confound properly tuning the truck, no?

Let's say I bought an Aurora twin turbo system, or BD Diesel, or Phatshaft, etc...do they all have the compressor wheel housing fitted with a port for the wastegate command valve?

 

Got an answer from NADP. Most the turbos they sell don't have the Wastegate Command Valve bung on aftermarket turbos so they simply tie up the Command Valve but leave it hanging.

So looks like I'm going to plug the little holes, drill and tap the plug and route the pressure directly to the wastegate.

 

You don't need it. The only reason you will need it is to leave it plugged in so the truck won't throw a code. I just got the adaptor plug from HTT which came with my turbo.

 

How old is your Garrett?

My Stage 2 has a plug in it from Garrett, or I can install the OEM Command Valve.



As soon as UDC is out for the Smarty I will be reinstalling the command valve and reprograming the ECM to regulate boost for me. I doubt it will ever do much as I don't break 33-34 psi right now, but I think it's easier for the ECM to limit boost to 40 with the command valve than guessing with the wastegate, just loosen the WG and let the ECM do it's job.

 

Yup...I had that plug too - but the instructions said if I had a command valve, to install it. So I did.

I have issue with the truck computer controlling the turbo - never 100% sure what it's doing (especially with all the mods).

I'm going to get another plug and directly connect the wastegate to the pressure side. I'll check what the wastegate is set at with a pressure tester to get some insight.

If I have problems with wastegate flutter, etc. I'd like to try an electronic valve controller (common in the import tuner community) like this one:

http://www.hks-power.co.jp/en/produc.../evc/6evc.html

They only control up to ~45 PSI but my Garrett apparently doesn't safely go over this pressure...so a non-issue for me...

 

If you have the command valve installed and uplugged it routes full boost reference to the WG and it functions like a mechanical system. If the controller is good and hooked to the computer then you will likely get some weird boost readings. The ECM will start modulating the boost to keep it at a preset parametes and with the mods you end will boost all over the place.

It is relatively easy to install a boost elbow to easily adjust the boost to desired levels. Unless oyu cna tweak and control the internal ECU parameters the command valve can be problematic as will any electrical control.