I have been gathering a few parts lately to push the 16g to its limits cheaply. You can follow this pursuit by clicking this link
So in my pursuit of happiness and keeping with the theme of performance mods on a budget, I decided to look into fabbing up a holset wastegate for my 16g. This is typically done for a few reasons. 1). The Holset wastegate actuator has a stiffer spring which should allow for not only more boost but also allow you to hold that boost level through out the rpm band. More on this later. 2). The Holset WG has a longer stroke than the MHI wastegate. This is handy because some have discovered their MHI WG's not opening the flapper valve fully ,which in some cases has been known to contribute to boost creep issues. A discussion on this topic can be found in this link.
Boost Creep: Modified WGA/Peepers Mod How-To - DSM Forums
3). By performing this mod, you also gain pretension adjustability which stock 14b or 16g actuators can not do. If yours is adjustable, it is not stock FYI.:thumbup
Here is a picture of the Holset WG Actuator
Wastegates and e3 o2 004.jpg
This is the non MHI 16g actuator that I picked up from a local. It has an adjustable shaft.
Wastegates and e3 o2 001.jpg
In this picture, you can see where I had to drill out the spot welds of the 16g actuator. I actually got lucky here, the spacing between mounting bolts on the Holset WG are 32mm apart which just so happened to be the distance of the spot welds on the MHI bracket. Drill these spot welds out with a 1/4 inch bit and the holset wga bolts right up. Naturally you can reposition the orientation of the boost source nipple if you desire. The 16g WGA positions it in nearly a 12 O' clock when mounted to the turbo making it a little difficult to reach. I positioned it at about 3 O' clock by mounting the holset WGA 90* clockwise.
Wastegates and e3 o2 002.jpg
Here You can see the spot welds that were drilled out.
Wastegates and e3 o2 003.jpg
The next three pictues show the Holset WGA mounted to the 16g bracket.
Wastegates and e3 o2 013.jpg
Wastegates and e3 o2 005.jpg
Wastegates and e3 o2 006.jpg
The Holset WGA supposedly allows you to hold boost at a higher rpm. In my setup that is controlled by a Greddy Profec B spec II, I hit 24-25 psi dropping to around 20 by redline. This mod gives you a higher spring tension, allowing the WGA to overcome the high pressures that are acting upon it at high rpm. You must think of your WG flapper as a lever. That lever will want to open as the force acting on it becomes greater. As your RPMs climp, there is more air being forced in and out of your motor which means that it has to push all of that air through the Tdo5 housing. The TD05 housing is undersized already so as rpms increase, so does the pressure in the housing. This mod allows you to resist the pressures longer through out the rpm range. That is the theory behind it anyway. I must say that this mod has been proven to work with nice results. Info on that can be found in these two threads.
Looking for a STRONG Internal Wastegate Actuator? - DSM Forums
EVO3 16g dyno results - DSM Forums
Now, on to the shaft mods. So, as pictured the 16g actuator that I picked up has a straight shaft with an adjustment tool. A MHI actuator will look like this. I didn't want to cut on this actuator so that I have a backup in case of catastrophic failure or incase something didn't go as planned. I like to call it CYA.
Wastegates and e3 o2 009.jpg
The straight shaft with adjustment was a problem, because the holset already has an adjustment, and the shaft actually needs a bend where the adjustment tool is. So I cut of the shaft of my t25 actuator. It was a straight shaft also, but it could be bent and did not have the threaded adjustment.
Wastegates and e3 o2 015.jpg
I then cut this shaft to lenght by measuring the length of the stock shaft, and measureing the length of the holset shaft. Take into account the coupling nut that I used which was 7/8ths of an inch. If you divide 7/8" in half, you get 7/16". This means to center my coupling nut on the end of the shaft, it needs to be threaded 7/16" onto the shaft. This will provide equal adjustment either way. Once this is done, you can then find out how long you need to cut the shaft to be welded. In my case it needed to be right around 3". When Cutting this shaft I allowed for a margin of error so that I could grind the shaft flat and at an angle so that it sits flush with the coupling nut for welding.
This picture shows the angle that I had to bend the t25 shaft.
Wastegates and e3 o2 007.jpg
This picture shows the angle at which I had to grind the shaft so that it sat flush with the coupling nut for easy welding.
Wastegates and e3 o2.jpg
This shows the bend compared to the mitsu shaft.
Wastegates and e3 o2 008.jpg
This picture shows the bent shaft butted up against the coupling nut and how it will look once welded.
Wastegates and e3 o2 011.jpg
Thats it for now. I will be editing this thread within a couple of days once I find someone to weld it for me. I plan to do back to back testing of the two wga's without my electric boost controller and with my electric boost controller. This way I can provide useful information to all. Heck after its all done, I might slap on my old MBC and sell the EBC. Time will tell.
If anyone has any idea as to how I could bench test both actuators to find out what pressure source it takes to open the valve, I would greatly appreciate it. I am up at school with no compressor aside from the gas station but I would need to increase pressure incrementally until it opens and still be able to read the pressure.
I must say that I got the idea from Jusmx141. He answered several questions that I had and was a big help. This was all prior to finding his thread. lol Noob status for not searching properly.