HKS SS Racing wastegate for RX6 kit
08-24-02, 11:43 PM
#1
WWFSMD
Thread Starter
HKS SS Racing wastegate for RX6 kit
A while ago, I got an HKS Stainless Steel Racing wastegate (different from the standard Racing model) to replace my A'PEXi wastegate in my RX6 kit after I had trouble with the A'PEXi unit (slow response on the track, and one big overboost on the way home from the track, but it seems to work properly most of the time). Today I finally got around to installing it, or at least starting the install. I know some of you folks have been wondering about this, so I will post more info as I complete the job. Here's the first report.
As expected, the manifold side has exactly the same bolt pattern as the A'PEXi wastegate, so it should bolt right up. The HKS comes with its own gasket, studs, and nuts. The studs are slightly smaller diameter than the A'PEXi ones, but I don't expect that to be a problem.
The bolt pattern for the dump tube is just slightly different. It is so close that I intend to simply open the holes on the dump tube flange a little bit and bolt it up. I expect to remove about 0.5 mm from the inner side of the holes to get it to fit. I was going to do that tonight, but I broke my only Dremel grinding stone that fits in the bolt hole. I was able to remove a little material before I did this, so I think it should be fine if I get another stone (and maybe some spares) and do the grinding carefully.
The HKS wastegate comes with "Allen" head screws to connect the dump tube, and its own gasket (so I won't need to slot the A'PEXi gasket). I might use some SS washers on the dump tube screws to make sure they seat against the back of the dump tube flange better. They are smaller than the A'PEXi studs and nuts that are normally used for the dump tube connection. It also comes with manifold and dump tube flanges, but I am just going to use the A'PEXi ones. I will, of course, use the valve seat that came with the HKS wastegate.
The dump tube will in almost the same place, but the HKS wastegate does move the tube 1-2mm closer to the center of the wastegate. I don't anticipate that this will be a problem, but I'll have to report back once I get it all bolted up.
I don't know if this might be related to inconsistent behavior of my A'PEXi wastegate, but two of the six "Allen" head screws that hold the diaphragm housing on are missing. Both chambers seem to hold as much pressure as I can blow into the chambers (which is not very much pressure, of course), but perhaps they leak under higher pressure or when the unit gets hot. If you are running the A'PEXi unit, you might want to put a drop of thread lock on these or at least make sure they are all tight (but be careful not to over-torque them). The valve and seat look fine.
I'll post again when I finish the install, which should be tomorrow if everything goes well.
-Max
As expected, the manifold side has exactly the same bolt pattern as the A'PEXi wastegate, so it should bolt right up. The HKS comes with its own gasket, studs, and nuts. The studs are slightly smaller diameter than the A'PEXi ones, but I don't expect that to be a problem.
The bolt pattern for the dump tube is just slightly different. It is so close that I intend to simply open the holes on the dump tube flange a little bit and bolt it up. I expect to remove about 0.5 mm from the inner side of the holes to get it to fit. I was going to do that tonight, but I broke my only Dremel grinding stone that fits in the bolt hole. I was able to remove a little material before I did this, so I think it should be fine if I get another stone (and maybe some spares) and do the grinding carefully.
The HKS wastegate comes with "Allen" head screws to connect the dump tube, and its own gasket (so I won't need to slot the A'PEXi gasket). I might use some SS washers on the dump tube screws to make sure they seat against the back of the dump tube flange better. They are smaller than the A'PEXi studs and nuts that are normally used for the dump tube connection. It also comes with manifold and dump tube flanges, but I am just going to use the A'PEXi ones. I will, of course, use the valve seat that came with the HKS wastegate.
The dump tube will in almost the same place, but the HKS wastegate does move the tube 1-2mm closer to the center of the wastegate. I don't anticipate that this will be a problem, but I'll have to report back once I get it all bolted up.
I don't know if this might be related to inconsistent behavior of my A'PEXi wastegate, but two of the six "Allen" head screws that hold the diaphragm housing on are missing. Both chambers seem to hold as much pressure as I can blow into the chambers (which is not very much pressure, of course), but perhaps they leak under higher pressure or when the unit gets hot. If you are running the A'PEXi unit, you might want to put a drop of thread lock on these or at least make sure they are all tight (but be careful not to over-torque them). The valve and seat look fine.
I'll post again when I finish the install, which should be tomorrow if everything goes well.
-Max
08-25-02, 12:12 AM
#2
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Max do you have your wastegate plumbed back into your downpipe? I do and i'm wondering if they would be a fitment problem with the HKS unit over the APexi. Since I also want to do this mod I'm curious if my allen heads are missing too, hummm gotta go check..brb
-Ed
-Ed
08-25-02, 12:57 AM
#3
WWFSMD
Thread Starter
I have a "poor man's" re-route of the dump tube back into the downpipe. Basically, there is an elbow welded to the downpipe that ends up right in line with the (slightly modified) dump tube end. I connect it with a muffler bandage (the Red plasticky-looking ones work better than the "high temp" ones, BTW) and clamp over the bandage with a wide SS t-bolt clamp. As you migth imagine, this doesn't work very well. It leaks most of the time and I have to replace the bandage all the time. I plan to get it done "for real" after I get the wastegate installed and finish up some other projects.
I don't think the slightly different position will be a problem for me, and I know one other owner that got his dump tube replumbed with a slip joint that isn't expecting any major trouble. If you have a bellows section or slip joint, this probably won't be a big deal. The new position is very close to the old position, and you should have some kind of flexibility built into the dump tube to allow for heat expansion anyway. I hope it will be enough to avoid trouble, but I think you'll just have to try it and see.
I am not sure I was that clear in my first post, so here's a good way to imagine the change in dump tube position: Imagine that 1-1.5 mm (I just measured it) was milled off the surface of the wastegate where the dump tube connects. Acutally, I just thought of a possible solution if your dump tube routing isn't flexible enough to absorb the change. Use both the HKS and A'PEXi dump tube gaskets to keep the dump tube in the same place. Actually, I just compared the gaskets and the HKS looks a little thicker, so the change in position may be more like 0.5-1 mm with it all bolted together. I am thinking now that this shouldn't be a problem for anyone.
Another note from the install progress: the HKS wastegate does not come with nipples for the wastegate control signals ("vacuum lines"), but it looks like the ones from the A'PEXi wastegate will screw into the holes on the new wastegate without modification.
-Max
I don't think the slightly different position will be a problem for me, and I know one other owner that got his dump tube replumbed with a slip joint that isn't expecting any major trouble. If you have a bellows section or slip joint, this probably won't be a big deal. The new position is very close to the old position, and you should have some kind of flexibility built into the dump tube to allow for heat expansion anyway. I hope it will be enough to avoid trouble, but I think you'll just have to try it and see.
I am not sure I was that clear in my first post, so here's a good way to imagine the change in dump tube position: Imagine that 1-1.5 mm (I just measured it) was milled off the surface of the wastegate where the dump tube connects. Acutally, I just thought of a possible solution if your dump tube routing isn't flexible enough to absorb the change. Use both the HKS and A'PEXi dump tube gaskets to keep the dump tube in the same place. Actually, I just compared the gaskets and the HKS looks a little thicker, so the change in position may be more like 0.5-1 mm with it all bolted together. I am thinking now that this shouldn't be a problem for anyone.
Another note from the install progress: the HKS wastegate does not come with nipples for the wastegate control signals ("vacuum lines"), but it looks like the ones from the A'PEXi wastegate will screw into the holes on the new wastegate without modification.
-Max
08-25-02, 04:46 PM
#4
Ghost Ride the Whip
pictures are worth a thousand words, please post some pics max!
By the way, how come you didn't consider doing the modification to the apex'i wastegate that XSPower suggested a while back? I had the valve guide honed and took it to the track (drove about 4 hours worth of track time in 90 degree weather) and the car had absolutely no problems at all. Best of all, it only cost me $20 to do
By the way, how come you didn't consider doing the modification to the apex'i wastegate that XSPower suggested a while back? I had the valve guide honed and took it to the track (drove about 4 hours worth of track time in 90 degree weather) and the car had absolutely no problems at all. Best of all, it only cost me $20 to do
08-25-02, 11:47 PM
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Yo TiteFD,
Can you post some more info on this XSpower mod to the wastegate? I've never heard of it before and would like to do it myself.
Oh and Max, I spent a good 4-5 hours bending, notching and welding in a dump for my wastegate so I don't wanna modify it if possible. I'll see if I can post pics of it but like yours it's inline with the DP's last bend so it maybe in luck.
-Ed
Can you post some more info on this XSpower mod to the wastegate? I've never heard of it before and would like to do it myself.
Oh and Max, I spent a good 4-5 hours bending, notching and welding in a dump for my wastegate so I don't wanna modify it if possible. I'll see if I can post pics of it but like yours it's inline with the DP's last bend so it maybe in luck.
-Ed
08-26-02, 01:21 AM
#6
Ghost Ride the Whip
94sr2, to fix the apex'i wastegate just take it apart and get the valve guide honed .003' larger from a machine shop.
the valve guide is that copper/brass looking cylinder shaped circle which the valve stem goes through. On apex'i wastegates the valve stem gets hot and expands and then sticks shut, by honing the valve guide, the stem won't stick to it when it expands. I've done this modification and took the car to the track and had no problems whatsoever, it's a much cheaper alternative then to spend $500 on a new wastegate altogether
the valve guide is that copper/brass looking cylinder shaped circle which the valve stem goes through. On apex'i wastegates the valve stem gets hot and expands and then sticks shut, by honing the valve guide, the stem won't stick to it when it expands. I've done this modification and took the car to the track and had no problems whatsoever, it's a much cheaper alternative then to spend $500 on a new wastegate altogether
08-26-02, 02:03 AM
#7
WWFSMD
Thread Starter
The wastegate is in now and working great. Here are some more tips I picked up from today's install:
- Everything fits together well. I suspect that no one would have any problems connecting the dump tube, even if you have it permanently fixed to the downpipe with no slip joint or bellows. The position is so close to what it was with the A'PEXi wastegate that it should bolt right up no problem.
- I tried a new stone for the Dremel and quickly shattered it. It may be possible to grind the dump tube flange holes with a Dremel, but I was either not careful enough or it is just hard to do. I did purchase a round file while I was out getting the new Dremel bit and ended up doing most of the work with that. After 15-30 minutes of filing, the flange bolted right up. In hindsight, it probably would have been a good idea to make some extra room to avoid shearing the bolts if the flanges expand at different rates. I just got it to where I could turn the screws in all the way with my fingers, but the dump tube was held in strict position with the screws in. You should probably be able to wiggle it a little.
- Get longer studs for the manifold connection. You can't reuse the A'PEXi ones because they are bigger, and the HKS ones were just long enough to get the nuts on 3/4 of the way. I am concerned that the locking part of the nut is not engaged enough and that they will work loose. I'm going to watch to see if any come loose, but I recommend that you use longer studs if you will be installing this wastegate on the A'PEXi manifold.
- Get new nipples for the wastegate signal hoses. I removed both of these from the A'PEXi wastegate and both of them took a lot of threads out of the holes when they came out. I used a 1/8 NPT die to clean up the threads and they worked fine, but there is no sense in stripping the holes in the A'PEXi wastegate if you can avoid it. Also, you probably want a straight one and a 90 degree nipple, as the positions are different on the HKS wastegate and those would be the best choices. The 90 degree fitting should go in the side port and it should point to the right when viewed from the top (diaphragm end) of the wastegate. I am not sure if you can use brass ones, as the environment might be too hot or something. Brass may be fine, but I just don't know, and the A'PEXi ones seem to be high nickel steel or something like that.
- Have a 5mm "Allen" driver to put on a small socket wrench. It would probably also be a good idea to pick up a T-handle driver with a rounded head so you can turn it from different angles. This will help when connecting the dump tube to the wastegate.
I probably could have just had the A'PEXi wastgate modified like 1Fookn suggests, but I already bought the HKS wastegate before that solution came to light, and the HKS wastegates have a good reputation for reliability already. If I was installing a new A'PEXi kit, I would probably just get the wastegate modified and run a pop-off valve just in case. I should get myself a pop-off valve anyway, but I don't have one yet.
So there you have it -- the HKS SS Racing wastegate makes a good replacement for the A'PEXi gate if you ever need one.
-Max
- Everything fits together well. I suspect that no one would have any problems connecting the dump tube, even if you have it permanently fixed to the downpipe with no slip joint or bellows. The position is so close to what it was with the A'PEXi wastegate that it should bolt right up no problem.
- I tried a new stone for the Dremel and quickly shattered it. It may be possible to grind the dump tube flange holes with a Dremel, but I was either not careful enough or it is just hard to do. I did purchase a round file while I was out getting the new Dremel bit and ended up doing most of the work with that. After 15-30 minutes of filing, the flange bolted right up. In hindsight, it probably would have been a good idea to make some extra room to avoid shearing the bolts if the flanges expand at different rates. I just got it to where I could turn the screws in all the way with my fingers, but the dump tube was held in strict position with the screws in. You should probably be able to wiggle it a little.
- Get longer studs for the manifold connection. You can't reuse the A'PEXi ones because they are bigger, and the HKS ones were just long enough to get the nuts on 3/4 of the way. I am concerned that the locking part of the nut is not engaged enough and that they will work loose. I'm going to watch to see if any come loose, but I recommend that you use longer studs if you will be installing this wastegate on the A'PEXi manifold.
- Get new nipples for the wastegate signal hoses. I removed both of these from the A'PEXi wastegate and both of them took a lot of threads out of the holes when they came out. I used a 1/8 NPT die to clean up the threads and they worked fine, but there is no sense in stripping the holes in the A'PEXi wastegate if you can avoid it. Also, you probably want a straight one and a 90 degree nipple, as the positions are different on the HKS wastegate and those would be the best choices. The 90 degree fitting should go in the side port and it should point to the right when viewed from the top (diaphragm end) of the wastegate. I am not sure if you can use brass ones, as the environment might be too hot or something. Brass may be fine, but I just don't know, and the A'PEXi ones seem to be high nickel steel or something like that.
- Have a 5mm "Allen" driver to put on a small socket wrench. It would probably also be a good idea to pick up a T-handle driver with a rounded head so you can turn it from different angles. This will help when connecting the dump tube to the wastegate.
I probably could have just had the A'PEXi wastgate modified like 1Fookn suggests, but I already bought the HKS wastegate before that solution came to light, and the HKS wastegates have a good reputation for reliability already. If I was installing a new A'PEXi kit, I would probably just get the wastegate modified and run a pop-off valve just in case. I should get myself a pop-off valve anyway, but I don't have one yet.
So there you have it -- the HKS SS Racing wastegate makes a good replacement for the A'PEXi gate if you ever need one.
-Max
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08-26-02, 02:40 AM
#8
Ghost Ride the Whip
pictures max! pictures! Seriously though, I'm sure everyone is curious as to see how well the hks ss wg fits. compared to the apex'i wastegate, how well does it fit from a scale of 1-10 10 being an exact bolt on to 1 being a total ghetto rig?? also keep us posted if you get your car retuned at higher boost levels
08-26-02, 02:24 PM
#9
WWFSMD
Thread Starter
I'd say the fit is an 8 or a 9 considering that you need to slot the holes in the dump tube flange. I don't consider it a rig -- I am pretty amazed how similar the two wastegates are. I bought a TiAL at first and while it was a very nice wastegate, it would have required a bunch of fitting and welding to install. And I don't have a welder. The HKS install only requires a round file and a little elbow grease to make it fit. Anyone could do it.
-Max
-Max
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