Agreed 110%...

I've got both HKS and Flyin' Miata cast manifolds and the FM is much thicker and heavier everywhere. I wouldn't do it with the HKS.

Stan Levine has since abandoned that design and built his own manifold to replace it.

I recommend running the internal wastegate before modifying the HKS manifold. It tends to crack in the bottom of the collector without any modification. I know, mine was welded twice and cracked again. If you want external then I highly recommend running a different manifold and selling your HKS in the usable condition it is in now.

If your port your turbine housing WG port like BEGI I bet you'll be fine.

I know like nothing about fluid dynamics but I'd be willing to bet that because of the location of the port that it creates turbulence in the housing which would significantly affect spool...

I don't think it would affect spool much at all because the WG should only open after target boost has been hit.

Thats not the issue the issue is that the placement affects the A/R ratio of that part of the turbo so that it isnt transitioning properly. It would never flow quite as good as a turbo that wasnt like that.
But unless you just want to pick the fly shit out of the pepper, its probably fine, and Im sure plenty of people have used them successfully.

I would have to agree that this design would have an effect on efficiency. This would not so much hurt spool however, it would hurt with boost spiking I am sure. This would be due to the high velocity air being pushed through the turbine housing. And in Physics, the material (air in the case), will take the path of least resistance. In this case, the air is more likely to continue through the turbine housing rather than make a 90° turn into the wastegate. So the opening of the wastegate will be slightly delayed thus causing a slight to mild boost spike on the system. Thusly this is why when designing a manifold the optimal setup is to have the air have a direct path to hit the wastegate rather than making an extreme turn. :2cents:

It's almost ironic that the turbine housing with the port casted into it is in the same location that the championship winning endurance toyotas had it. And I doubt they stuck the port there because they didn't have anywhere else to put it. Gurney is not known for making compromises.

To the OP- what's the issue with the internal gate now? Why the urge for the external gate?

I like that wastegate turbine housing, looks like one solid piece.

^That I agree with... It may have been a way to take out a failure point as compared to adding a flange to the manifold. However, it sure does look nice... It's just that I can't get past the velocity that the incoming air would be carrying that would make it want to enter the port readily rather than pass by it and cause a slight overboost situation. Could they have installed it there to get the slight overboost situation? Essentially a 'sneaky sneaky' way to get some extra horsepower that might not make flags fly during inspection? Then all they would have to do is tune for this and done. Just a thought...

As far as being worried about overboosting, you can just set up your boost controller to open the waste gate at a slightly lower pressure and so when you would be going to over boost you would be at your target pressure.

Having not seen the inside my concern about that housing it that there is a 90* lip that would catch some of the air and create a sort of bubble affect from turbulence generate by that amount of air hitting that angle that would alter the flow of air right at that lip forcing air to not travel correctly though the housing. (see image for possibly convoluted worry, sorry for not using cad, I don't have it on the computer)

argh!

http://www.boostedmiata.com/technica...te_turbine.jpg

http://www.boostedmiata.com/technical/wategate_out.jpg

The above design would be much better if you had to run a turbine housing mounted EWG...

Finally done and works like a charm.

http://img97.imageshack.us/img97/9223/dsc0028i.th.jpg

http://img191.imageshack.us/img191/345/dsc0030z.th.jpg

Turbo no hit wastegate?

I ran accross this myself with my last car. I found a welder that did it with no guarantees and I had asolutely 0 problems. I will get some pics of it. Its a mildsteel tube welded right to a cast iron peice. The welder is in PHX and is truly top notch and explained that he essentially used something similar to a brazing rod, but much better. I am welding-stupid so I really dont know excatly what it means. But it supported the weight of my 38MM and the 2 foot dump pipe under very hot conditions (the ar ran very rich with little timing advance meaning tons of heat) without any problems. This was on a OEM 2G DSM ex mani. Pretty weird setup actually, you dont see a lot of internal and external gated 16gs LOL.

This is a good point too. I did not care much if I cooked a stok 2G mani because they are a dime a dozen anyway. Not neccesarily the case here.

This is a fantastic design really. Its totally correct that the fluid will take the path of least resistance. So what makes one path easier than another to take if you are a very hot gas with a relatively low density and high pressure?

Pressure differentials. A proper wastegate mounted to that location opens up a huge low pressure path of the hot exhuast gas relative to the turbine housing itself, which is inevitably a throttling device that creates high pressure. The hot exhuast gas has 0 trouble 'making the turn' because of all the forces affecting each little particle of exhuast gas, inertia is was down the list. Inertia is pretty much the only thing that makes it diffcult to for a particle to turn like that in this case because the port has plenty of volume and I assume no huge chuncks of metal in the wg passage.

Basically, gas will flow right out that port in higher volumes than going through the turbo untill the pressure going out that port is equal to the back pressure of going through the turbine housing itself. This is good.

You might get a bit less laminar flow through that thing, but my bet is that its pretty much unmeasureable on the dyno at any RPM in terms of boost threshold or TQ from one setup running that and another running a collector-mounted EWG.

Nope :)

Nice work man, I had my doubts when I started reading the thread but looks like you pulled it off. Any pictures of everything all mounted up?