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I recently acquired a set of HKS Internal Wastagete Actuators for use with my Stage2 Turbochargers and felt like sharing the process of properly installing a set. Fabricating the HKS brackets for use with varying compressor housings isn't terribly difficult to do and it has turned out to be much easier than cutting out your own brackets and bending them to shape. Just a little cutting and welding to do the trick. Granted, you will need a welder to do each of the welding steps along the way. Although the fabrication of the brackets is an obvious component that will have to be modified in order to install the actuators on anything other than a stock compressor housing, what may not be so obvious is the modification that should be performed to the wastegate control arm. When turbocharger turbine housings with internal wastegates are assembled, the wastegate control arm is typically welded perpendicular to the turbine outlet flange, however, this is not always going to be an ideal angle when the actuator is placed with the control rod anywhere other than the down the centerline of the turbo. The diagram below illustrates what I mean.
As shown above, the actuator has been arbitrarily set for 15# of preload pressure. The top image shows that with a 90-degree rod-arm angle, the effect on the wastegate itself will be the full force of 15# applied to holding it shut. The second image shows what happens to that holding pressure when the rod-arm angle is at 45 degrees. You can see that there is a substantial loss in holding pressure applied in this car. Any angle other than a 90-degree actuator rod to wastegate arm is going to produce less clamping load per preload put on the actuator when installed. If you look closely at the stock turbine housings, they are actually different from each other in this one respect. Both of the wastegate control arms are mounted with slightly different angles from each other as the driver's side turbocharger has the actuator placed quite a bit off from center of the turbocharger. When nissan developed the stock turbos, they took the rod-arm angle relationship into account. It is critical that both turbocharger wastegates operate in syncrony. It is typically the driver's side turbocharger on aftermarket turbos that creates the majority of the problems for the sole fact that builders are not taking the rod-arm angle relationship into account when assembling them. One of the steps in assembling turbochargers is to balance the actuators so that they both begin opening at the same time at a given pressure. Adjusting the actuators such that this occurs is rather simple to do, however, if the rod-arm angle is not 90 degrees, the turbocharger that has the greatest deviation from this angle will actually open before the other. Balancing turbocharger actuators solely on opening pressure is only 1/2 of the job - getting the rod-arm angle relationship is the other half and it comes before the opening pressure calibration. In the images to follow, I will note the process I used to install a set of HKS actuators onto a set of Stage2 turbochargers. These turbochargers are equipped with a stock 5-speed turbine housing (.63 A/R) that has been machined for a larger turbine wheel, and it has a T04B .60A/R compressor housing. This is the same compressor housing used on the JWT Sport700s, which is also the GT28RS turbo sold by Garrett. This procedure will directly cover the setup on these turbochargers, but a lot of the theory behind it will apply to all internally wastegated setups.
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First Things First...
I have taped the center cartridge with packaging tape to protect the oil inlet and outlet from getting any debris into the delicate bearing area of the cartridge. The work you will be performing will generate a degree of small metal particles that will damage the turbo if they find their way into it. Tape the center cartridge up using clear tape so you can visually inspect that the tape is completely seated around these ports.
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The first step in our process is going to be drilling out the weld holding the wastegate arm in place. I used a 19/64" cobalt drill bit and a centerpunch to mark the spot. Drill through the top of the plate about 1/16" and use a pair of pliers to break the arm free from the wastegate shaft. Set these aside for now.
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We will start with the driver's side turbocharger. I have attached the actuator to the bracket using the non-locking nuts for quick install/removal during the fabrication process. You will be installing the actuator and removing it from this bracket several times in the process while checking fitment along the way, so be sure to use the non-locking nuts until the final assembly.
You can see how the actuator rod is coming in at about a 40 degree angle from the centerline of the turbo. If the actuator were installed like this, even with 15# of actuator preload you would only have a total of 11.5# of acting load on the wastegate. Although we can put the wastegate arm back on at any angle we wish, there is a problem here: the rod isn't long enough to give ample thread engagement of the adjustable collar with it so far from the wastegate arm. We will need to move it closer to the centerline of the turbo and modify the bracket to get the proper angle of actuator.
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Using an anglefinder, I roughly determined that we will need an 18-degree offset in the angle of the bracket. I marked a new line showing where the bracket needs to be cut.
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Be sure to break the small 6X1.0M nut free that is fastened to the backside of the bracket. Thread a bolt into the hole and place over a vice as shown and hit the top of the bolt with a hammer.
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The nut has been broken free - remove this piece and discard it.
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Place the bracket into a vice as shown and using a hacksaw or portable bandsaw, cut the bracket along the line.
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Once you have done this, place the actuator plate in the vice and cut the remaining piece of the bracket free.
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Testfit the piece and ensure that your angle is proper.
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Remove the bracket from the turbo and remove the actuator from the bracket. Place the bracket into a vice and tack-weld the plate into place.
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Put the actuator onto the bracket and test fit once more after the tack-welding.
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Using a marker, place a position indicator for the location of the compressor housing bolt.
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Place the bracket into position, noting the location of the actuator rod to the wastegate shaft, and draw a locating mark on the bracket.
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On these turbochargers I measure a distance of 0.400" from the hole center to the location of the bracket edge. Mark your hole center and drill a 19/64" hole in the bracket.
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Attach the bracket to the compressor housing.
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Install the actuator and check for fitment.
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If everything fits properly, apply your final weld to your bracket.
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Attach your bracket to the housing and apply a small tack weld between the bracket and the housing retainer plate. This will ensure that there is no rocking of the bracket since we are only able to use one mounting hole.
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Final install your actuator using the self-locking nuts provided in the kit. Be sure to point the actuator hose nipple in the orientation shown.
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Install the actuator rod locknut and collar and place the wastegate arm into position. Adjust the rod length until you have a 90-degree angle between the actuator rod and the wastegate arm.
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Using a circular motion with your MIG welder, fill in the hole to re-join the wastagate shaft to the arm. One thing to note while doing this - be sure to push the wastegate upwards and hold it shut before you make the weld. If you dont do this, the wastegate will likely be lower than it should and not fully closed - this will defeat the purpose of repositioning the arm, so be sure of this before you lay your weld in.
At this point, you have completed the first half of the setup of the driver's turbo actuator.
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Passenger Side
In this picture I have setup the actuator and arm in the position that I ultimately want to install it in. This position will give us the best possible fitment of the actuator onto the turbo for mounting onto the engine.
The passenger turbocharger is a difficult turbo to install the actuator onto due to the limited space on that side of the engine. The actuator is between the cylinder block and the compressor housing, and in many cases, the engine mount bracket gets in the way. The location I am putting this actuator into works on my engine as it has for many other turbos I have setup, but you will need to verify that everything fits reasonably along the way. This section is more/less a guideline for fitment so be sure to trial fit everything before committing to a final weld of the bracket.
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To start, remove the two small 6X1.0M nuts that are spot-welded to the bracket. These WILL get in the way if not removed.
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Trial fitment of the bracket. I had to open the hole in this location of the bracket up to a 19/64" hole to get the fastening bolt through.
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The shape of this bracket puts the actuator mounting plate too far away from the compressor housing and it will interfere with the cylinder block. Mark the bracket with a line tangent to the periphery of the compressor housing as shown:
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Cut the bracket and mount as shown.
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Cut the remaining edge from the top half of the bracket flush with the leg of the actuator plate.
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Spot-weld the bracket into place and check for fitment on the engine. I ended up trimming 1/4" off the bottom of the plate leg after this image to drop the actuator closer down to the wastegate and allow room for clearance of the engine mount bracket.
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Once you have massaged the parts for proper fitment, apply the final weld to your bracket.
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Install your bracket and actuator onto the turbo.
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Install your locking nut, collar and wastegate arm, taking care to get that 90-degree angle.
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Final weld your wastegate arm, again taking care to position the wastegate closed and in the upper-most position prior to welding.
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Be sure to weld the bracket to the compressor retaining plate by filling the second hole in the bracket's mount.
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At this point, you will have two turbochargers ready for actuator pressure calibration and balancing. For these particular units, I suggest applying at least 15# of preload pressure on them. This will produce a base pressure of 15# at the intake manifold and provide enough wastegate holding pressure to achieve full boost of the turbo.
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This process, in whole, took me 1 hour and 45 minutes to complete. Another 15 minutes and the actuators can be pressure calibrated and balanced. I have been writing this post for close to three hours and it is finally done. Enjoy!
[ ashspecz.com ]
[ agpowers@bellsouth.net ] Enthusiasts soon understand each other. --W. Irving.
Are you an enthusiast? If you are out to describe the truth, leave elegance to the tailor.
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Turbocharger Wastegate Actuator Setup >>>>> - 
