BlaCkPlaGUE

Yea this one I think is crazy, but tell me why it wouldn't work.

Wastegate placement is always an issue when it comes to manifolds and such. You want to make a wastegate flange inline with the exhaust gases for smooth gas release. However, when its in line like that, the longer the tube, the more resistance/turbulance you get, wich in turn means more heat, right? please correct me if im wrong on that one..

So, what iF!!!! you mounted the wastegate on the turbine housing? im not talking a pipe that splits off, im talking about a perfectly plumb wastegate valve inline with the turbine.

So imagine a wastegate that is specially made for this, where the actuall valve of the wastegate is flush with the inside of the housing, so that when its closed exhaust gases run smoothly against it and spin the turbine with no turbulance. When it opens, since its in line, the gases flow right out? right?

Keep in mind that I don't own or have ever owned/tuned/setup a turbo car as of yet, so don't chew me out if this is dumb. Not that you guys ever have or anything..

thx

surfpac

No, it is not crazy. Setzep is running his wastegate runner right off the turbine housing with no boost creep issues. PM him about your idea.

CrackHeadMel

iTrader: (2)

There is a blurb in Maximum boost about the effectivness of the Toyota GTP turbo motor iirc (books at work) and they mention how a major part of its sucess is the WG placement, which is very simmiliar to what you describe

-Jacob

setzep

That is my setup

BlaCkPlaGUE

That is EXACTLY what im talking about! nice thinking man.

Too bad you couldn't make the valve curved to the turbing housing itself for even better flow! Im sure you could get some kind of machine shop to make a custom curved valve if you really wanted.

GOTBANNED?

hey do you have a better pic of that? and how did you exactly do it? shed some light on it if u can plz

BlaCkPlaGUE

Just curious, but why in the hell don't the turbine housing come out of the factory with a wastegate mount? Its so much better there.

setzep

The pipe is 304ss and is welded on with a TIG using silicon bronze rod. I simply cut a hole/slot on the back side of the turbine housing and formed a small chunk of pipe to fit it.

I'd say turbos don't come this way because it's too expensive and it takes up a lot of space which is a shame because it works pretty well.

GOTBANNED?

did you route your waste gate back in the exhaust ot atmosphere? how well does the boost hold?

setzep

http://www.datsunracing.com/z/setzep

Link is to a few pic's of what I've done to my car. The second pic should answer your question on the DP.

Boost will hold pretty solid unless it's *** cold then it will creep ~2psi. But that might have to do with my timing being too far retarded.

GOTBANNED?

wow thats some nice work man..looks great..where did you get that flex from though? looks real clean.

vintagespeed

In some factory T3 setups they run an external wastegate mounted to the turbine housing.

-jb

setzep

I got the flex tubing from a buddy that works at a exhaust manufacture. It can be found on the net though.

onePOINTthree

atpturbo offers something like this on their evo kit

BlaCkPlaGUE

Still not as good, that looks like a divided housing and its only catching half of that exhaust gas.. The actual turbine Housing, right where setzep welded it is the BEST way. Its in line with the exhaust gas, it vents ALOT of exhaust gas (excellent boost controll) and creats MINIMAL turbulance.

Im just wondering with the right person in machining, if you could make up your own wastegate valve that is perfectly in line with the inside of the housing, curved if I could say exactly what im talking about. There would be of course a curved flange with the curved valve, but when the exhaust gasses run over it, it would be like the wastegate was never there!

I'll do it someday

astrochild7

iTrader: (3)

excellent placement... always toyed with the idea, just haven't gotten there yet...

88fc3sw/HX83

Setup's looking GOOD !

efiniracer

Hey all! I had a few questions/comments about SETZEPS idea. I think it is a really good idea, and I would like to do it myself, and I probably will in the near future.

I was wondering if anyone has calcualted any flow characteristics while the wastegate is closed?
When the wastegate opens, exhaust nearly has a straight shot out, which will greatly help with wastegate response time, venting and all sorts of good stuff. But what about when the W/G is closed?

When it is closed, you want as much of the exhaust energy going through the volute to the turbine wheel as possible. But now that the volute has been machined out to accept this pipe, the inside of the volute is not symmetric and smooth anymore at this point. So will this create an adverse boundary layer in that zone of the volute? Is this why the wastegate runners are always so long on most of the existing manifolds? By having that long runner, you would minimize the chances of creating a boundary layer, but you would have decreased W/G performance.

I'm a Mech. Engineering student, and next quarter I am taking fluid dynamics, where these types of principles are taught. But I am curious about it now, as I would like to do this myself on my own project! If anyone has any more info on this, it would be greatly appreciated.

setzep

I'm guessing with the valve closed there is a bit more pressure in the chamber I created (the small 3" chunk of pipe) by cutting a hole in the side of the turbine housing. With the higher pressure in this area the gas isn't going to want to flow so it takes the easier route, out the turbine wheel.

Any place you put the gate there will be a drawback, I think this loation is about the best compromise for my setup. I don't run large amounts of boost so I need my extra exhaust energy to go somewhere. I'd think if I were to run 20psi I could probably get away with putting the WG anywhere I wanted it.

Havoc

hmm Ive done a bit on fluid dynamics as well an would of thought you would get a massive amount of turbulance with the waistgate pipe coming off at the start of the turbo housing, if you where going to mount it on the exhast housing I would of thought to mount it on the other side of the housing as you would not creating turbulance for 95% of the gasses entering the system... but still Im no pro on turbo's

Still very interesting, would be great to have known if you had the manifold waistgate set up first then have this system to see how much of a difference their was

BlaCkPlaGUE

I think he did, and I think he also mentioned that it was a very noticable difference.

its sweet non the less.

rotarygod

iTrader: (1)

You should see examples just like your question in fluid dynamics. Basically when you have that "dead pipe" when the wastegate is closed, you have a higher pressure zone right there compared to the rest of the pipe with no flow. The air will just simply go past it even though it is pointed at it. It isn't as bad as it seems in terms of flow and actually doesn't have much of an effect against it.

efiniracer

In regards to Havoc's reply, if he mounted it on the other side of the turbine housing, you might as well mount it on the exhaust runners. Not to mention, how would you fit it in that area anyway?

RotaryGod, Thank you for your input! I understand what you mean by "deadpipe" when the wastegate is closed. But when you say there is a higher pressure zone right there, is the pressure zone in the dead pipe, or the volute of the turbine? This is what I am concerned about! if it is in the volute, wouldn't this create some more backpressure, and you would not get as much CFM through the turbine? I understand that the dead pipe will be pressurized, but will it push into the volute?

Here is what I am envisioning: Remeber from Chemistry and the idea of surface tension and meniscus? when you fill a test tube/beaker/glass of water up to the very rim, it creates a bit of a dome on top of it due to the surface friction of the water. it is this dome pushing into the volute that I image happeneing, but on a much more dramatic fashion.

So I made an appointment with one of our fluid mechanics professors to ask him about this. For the sake of simplicity I just said it was a pipe with a 90 degree bend in it, and had the deadpipe coming off right at the bend. I accidentally said it was on a turbo; at whcih point he just sat back and said he didn't know, and told me I had to go to our campus vehicle research lab. Now, I haven't taken the class yet, but this is a fluids problem, not so much a thermodynamics problem right? You would think that a prof would be impressed that a student would go out of his way to try and understand a topic, and try to make a real world application out of a principle that would be taught. Now mind you, I made an appointment, so it's not like I just popped in. Just reinforces some of the thoughts I have about higher education and those that teach it. sorry about the rant, but just wanted to point out that I am trying to find the answer, so we can all benefit. I think that black plauge and setzep have a great idea; I wondered the same and thought I would be the first. damn.
-Chris

setzep

This is what I had before and it didn't work out for me once I was above 6300rpm. With a 7.25 WG spring it would creep to 17psi on a cold night with a open WG. I simply cut the WG runners off the manifold, patched the holes then moved the WG to the turbine housing.

efiniracer

do you have any problems with the turbo feeling like it is "choking" at high rpms? Kinda like you maybe had a 1" exhaust instead of a 3"? (This is just a "for example" type of question.)