Who and were did you get the idea it was a hot thing for turbo's? Ported shrouds have been around for a LONG time and this isn't any thing new at all. And for the last time, there not really meant for our application nor most performance car applications. However one good application of this is the HKS GT-RS Sport TWIN Turbo Kit (GT-R) turbo system for the Sky Line GTR. (there GT28 sized compressors)The turbo's can fight one another slightly and its a lot of "turbo" for a "small displacement engine" and they spool fast so some mild surge does happen, so HKS added the ported shroud to buffet this problem. For what its worth, you can interchange a great deal of compressor housings from one turbo type to another. A good example is using a T04S compressor housing machined for a GT 35 wheel. you get the smooth bell mouth doing this, but I can't vouch if theirs a slight gain in effiency or not, but I'm enclined to think yes.

And why isnt it done on high boosting big turbo's??? What GT35, GT40, HKS T51, and Y2K aren't big high boosting turbo's?????

I can only assume HKS did this to gain back some of the effiency loss by going to a ported shroud by making it a smoother transition. Maybe they only added the port shroud strictly for the sound it makes and didn't want to loose effiency? I dunno.

I don't have all the answers, you can always do a research paper for us and report back to us Search the net, but I bet you'll find better technical explanations in papers that describe the ported shroud on turbine engines. May find something on turbo chargers, but all I found in a brief search is the Power Stroke turbo from ATP.

~Mike..............

 

And to cap it off.... all the turbo's disscussed in this thread including the original posters and the HKS t51 and the Y2K pic I just posted HAVE PORTED SHROUDS, their not some adapter or an after thought of the manufacturers to go up a size on the inlet diameter. They have a purpose be it applicable to OUR application or not. This isn't a urban myth I swear . besides, explain the bleeds.

~Mike............

 

One thing that i would like to point out......Ted said that this is the "hot new" thing. It actually is. If you look around at quite a few of the turbo sites they are all starting to offer this as an upgrade. I've heard a lot of people talking about it lately as well. The Supra guys are buying these compressors up as fast as they can. I've seen and heard about these before but within the last 6 months or so it's getting a lot bigger.

The Supra guys are claiming all kinds of benefits associated with this compressor. I've never heard anything positive or negative really from these guys before or after. It seems as though it's just another way to make money.

 

I did't even know about it, until a Supra guy was looking at one of my pictures and pointed it out. When we ordered the turbo, Innovative gave us all the options... this one included I guess.

I felt funny when the Supra guy was asking me about my anti-surge housing, for at the time I didn't know what in the heck he was talking about.

 

Yeah ported shrouds have been around along time, I once found a detailed explantion on the ported shroud mechanics, complete with engineering data on it, on a schwitzer oriented website, I cannot for the life of me find it though, or remember the search criteria I used to happen across it, I wasn't looking for the shroud info at the time though...
My current t04e has the ported shroud, it was not a performance based t04e to begin with, its real application is on 8.0 litre ford diesels, from the early 80's to the late 90's in application...
Someone earlier said that it had an application on preventing surge on diesels when airflow exceeded requirements, and this would make sense as well, given that diesels don't run throttle plates, and thus no real need for a bov for most of the operating spectrum of the compressor, a simple device such as ported shroud to prevent minor surging at low speeds or deaccellaration, would probably extend the life of the turbo in long haul applications, aka heavy truck use, without adding another potential trouble spot to the turbo system by adding a bov with its hoses, springs, and valve/seat, the bov is a real simple device, but the idea on industrial diesel application, is to make something as simple as possible and to keep it that way...Max

 

A BOV wouldn't work (or be necessary!) on a Diesel. No throttle plate, remember? So no throttle plate to slam shut and generate manifold vacuum with which to open the BOV. Also, no throttle plate to slam shut and make the turbo try to flow ~0lb/hr while still spinning fast.

 

Yes, of course, you are correct.  I guess thinking "out of the box" is a fault of mine, since my mind goes into a certain mode everytime I come into this forum.

Again, you are correct.  Whenever you mention "surge" I immediately think "compressor surge", which is a little different from what you are describing in the usual sense of the term.

Yeah, I see it now.  It looks like a normal machined lip if you're not looking for it.

Thank you very much for the clarrification.

I haven't seen things like this except on Garrett units.  I don't believe any of the other well-known turbo manufacturers include this design in their compressor housings?  I know KKK / KKR runs very small compressor inlets, and there is no surge housing designed into them - but then again, I think they are primarily an automotive turbo manufacturer (Porsche , Audi, etc.)?


-Ted