first off my car: 06 IX MR
Licp, Fmic, silicon intake pipe w/ filter on maf, MBC
Ported Megan O2 housing, 3" turbo back w/ test pipe

While pulling my car apart for a bit of maintence and upgrading I decided to port the stock exhaust manifold. I was looking at the turbo and knoticed that there are a couple pretty severe "steps" in the exhaust housing. Mainly one that goes all the way around just before the turbine wheel.

I have been searching and trying to read the last few days, a lot of people have talked about if but nobody has talked about exactly where and how they are porting either one, I have a pretty solid idea how I am going to do the mani but not sure at all on the turbo.

I don't have the money or time to get it done professionally so please don't tell me to do that. Just looking for people that know for sure about doing this. Thank you.

 

Gasket matching alone makes a huge diff

 

Ya That's how I am doing it for the turbo and exit side of the mani but it is mainly the "step" by the wheel that I would like to smooth over but am not going to do with out 100% confirmation that I can or should

 

Good question. I did my intake and exhaust mani but I didn't have time or knowledge to do the turbo.

 

Man, nothin. Did you knoticed any improvement with power, spool or drive ability with just these mods?

 

It has been a long time since I ground out one, but I think that I can help you to some extent. Can you post up a pic with this "step" that you are referring to please. I think that you are talking about the twin chambered turbine inlet area of the housing in general, right?

 

I am assuming that it is the later, single-puck version of the 10.5cm housing, as opposed to the older, twin puck 10.5cm. version, right?

 

W/o a pic we need to make sure that we are talking about the same "step".

So, position the turbine housing on your work surface looking in at the turbine inlet area which is located inward from and directly beyond the housing's mounting flange. If you insert your fingers into the turbine inlet area of the housing about an inch+ you will feel that there is a transverse, shallow groove on one of the four interior surfaces that comprise the walls of the turbine inlet area. This is the feeder groove that leads into the wastegate's bypass ports.

Now, flip the housing so that the internal wall with the feeder groove is sitting at the bottom, closest to your work surface. We will call this interior surface with the cast in grooves the floor of the turbine inlet area. Capisci?

Is the "step" that you refer to the vertical step-up located directly beyond the feeder grooves? Beyond this step is a short shelf area and beyond this shelf, the entrance to the scrolls start, right? Are we talking about the same step? Sorry for any inconsistencies as without a pic, I am working strictly from memory, because my housings are back at home.

 

Hmmm. After rereading your original post I am not so sure that I understood you correctly. I realize now that you may, in fact, be referring not to the turbine inlet area, but rather to the turbine oulet area where the turbine wheel's exducer is housed.

This area can be ported as well. porting the turbine exit area is easier than porting the turbine inlet area. The turbine's exducer is shrouded by a casting bulge which is quite noticeable if you look straight in axially at the tip of the turbine shaft.

Sorry, if I went off on a tangent about the turbine inlet area when you were actually asking about the other side.

 

If you are talking about the concentric bore in which the turbine wheel's exducer resides, there is only a slight, very minimal concentric width beyond the exducer's outer circumference, right?

Well, I guess that with a stock TD06H wheel there is more material shrouding the exducer. On the aftermarket 16G variants with larger diameter exducers there is less shrouding as more material has been removed in making the cut for the larger diameter turbine wheels.

So, on a stock turbo with stock, relatively small diameter TD06H exducer there is probably more material to be removed in the turbine exit area.

Any pics?

 

I suspect that it's going to be difficult for you to get qualified, definitive, expert advice on how to port your turbine housing. There really haven't been comparative dyno tests done on different porting methodologies or techniques. So, in the first place, it's hard to say what actually works and what doesn't.

The aftermarket turboshops used to offer a pretty basic minimalist turbine housing porting job that was basically just a gasket match at the inlet area. Over the years their work has steadily improved to the point where shops such as CBRE/Blouch do a really nice and substantially complete basic porting job.

Aside from the commercially available porting jobs offered by the turbo shops, there have been a few much more radical, and truly innovative, one-off porting jobs done, such as the one that R/T Ernie did on Mikey's FP Black 10.5 turbine housing.

As I recall, R/T completely removed the divider wall in the turbine inlet area and maybe further up into the volute(?). Mikey and R/T refer to that housing as non-divided, or single-scroll. At least, AFAIK the entry is non-divided. I am still trying to get Mikey to show me some pics but R/T has him swarn to secrecy.

What I am trying to say is that the craftsmen that actually do the turbine housing porting keep their trade secrets close to the vest. So, unfortunately for us, not much detail is available from the people that actually do the porting professionally and are doing it well. This is understandable as it is the source of their livelihood and their porting secrets are hard earned.

 

Hey you definatly/ obviously know much more about this than me so I will clean it up a bit get some pictures here in a few and post them up and you can give some of your best judgement on it. Thanks for taking some time to help.

 

I'd be glad to help. No problem. I am no expert though. That's for sure.

Post up some pics. When you do the pics of the turbine inlet area you can backlight it with a small hi intensity light shining down through the wastegate bypass port etc. The divided turbine exit area/wastegate discharge area needs no special lighting as it is pretty shallow.

 

So I for the most part answered my own questions already but one of them is still with the picture below you can see the cleaner part/ shiner part down in there, there is a "step" not big but thought the gas flowing over it could be smoother if I took that down a bit and smoothed it out.


Then here at the flang I just plan to do a gasket match. I am working with a good carbide bit on the end of a drill so I can only reach into the housing about 1.5" maybe a little more, but not much.

 

You are gonna remove the collar ring and separate the exhaust housing away from the turbine wheel before starting any grinding on the housing, right?

With reference to your first pic: You could do an extremely slight, chamfer, outboard of the exducer tip circumference, but it is very minimal and it would be a fairly steep angle because you just can't touch much inward axially anyway. So, IMO it is almost not worth it at the exducer exit bore considering the risks and inaccuracies of working by hand at that particular juncture of the exit chamber.

You also need to make sure that you have the right bit for that job of chamfering that sharp step. The tip of a carbide burr is gonna want to walk on the sharp corner of that step. So instead, you'll want one of those longish, soft, pink stone compounds that's shaped like a doggie dick. I wouldn't use a carbide burr for that job.

In fact, since the bore for the stock TD06H wheel's exducer is relatively small there is no shrouding that needs to be removed anyway. It is just with the larger upgrade wheels that you see significant shrouding. When the machining cut is made to acomodate the larger diameter exducers, that step no longer exists anyway. It almost not worth it to mess with it at that particular juncture. An extremely slight chamfer at most would be all that you could do at that particular juncture.

Incidentally, since you mentioned not being able to go very deep due to your bits being short shanked... there are long-shanked carbide burrs available for cheap online that are great for doing those deeper grinding jobs at the turbine inlet area. These bits have 4-6" shanks.