Divided Turbo Elbows, how much do they actually do?

[HardVision]

Okay first off this is more than your basic "whats the point of them" thread. I've done a bit of digging and all I come up with is here-say. I know the theory behind them, and that they supposedly help throughout the entire engine operating range by cutting down on the amount of turbulence on the back side of the turbo.
The thing that is annoying me is I haven't found any aerodynamic flow simulation at the back side of the exhaust turbine that shows what is actually happening when the wastegate opens or anyone that has done a back to back test with an undivided elbow and then swapped out to a divided elbow. Frankly I think its sad how many sheep there are that go along with the "well they said" mentality when it comes to building a car, and I just can't stand to put something on my car and not know if it actually doing what it "should" be doing.

With that being said... school me.

[godsmack]

From my understanding of the way that they're designed eact exhaust runner to the collector length is more important than having the divided housing. The way it's supposed to work is almost at a cris cross pattern when the cylinders are firing. So when the pressure from the exhaust hits the turbo the different exhaust pressures don't conflict with the other one and then have a faster spool due to a continuous steady flow.

[Mikester]

Here is all you need to know- They don't really work.

What ends up happening is that they are not truly "divided"... so the welds on the wastegate side end up getting exhaust blown directly on them from the inside and will fail over time. *experience talking*

Get a wide-mouth standard aftermarket elbow and you will not be disappointed. With those, the turbine and wastegate gases can only go one way- out; flowing right by the welds and not directly on any of them.

Ultimately your choice. Just throwing my own experience out there. Others may have had good luck w/them; but if you look at most stock to well-built SR setups with bottom-mount turbines, you won't see very many divided outlets- if any at all.

Just my $.02

[Croustibat]

They are useless so dont waste your money on them. You cant get them to work on an internally wastegated turbo, so dont bother. On external wastegate, the joining is done way further to really have an effect, and you wont feel anything without using a big ass turbo.

[fliprayzin240sx]

Well, from my personal experience atleast, if you're gonna get a turbo elbow, get a Tomei one. Didnt think it would make a difference on my T518Z turbo but it made a big difference over my old screamer pipe.

[feito]

Here is all you need to know- They don't really work.

What ends up happening is that they are not truly "divided"... so the welds on the wastegate side end up getting exhaust blown directly on them from the inside and will fail over time. *experience talking*

Just my $.02

I have an amperformance on my stock rb and as u can see the design is a bit different, this short piece of pipe slides into the turbine's exhaust port, i imagine the deeper (which cant be more that 2 inch or less before u hit the wheel) it goes the tighter it gets because of the pipe design.
http://i1081.photobucket.com/albums/j341/andres14oj/Abbeville-20111130-00081.jpg
Anyway, at first I left the wastegate screamer open to atmosphere and it never leak until i build up boost which is when the valve cracks open (no boost controller) so im guessing it seals good. But damn was that thing loud, i just couldnt take it and got it recirculated down by the tranny, shi+ was annoying as hell. Oh yeah, i didnt feel any difference after i got it recirculated.

[OrangeVirus1]

here is the honestly truth. it might make like a 1-5HP difference, once you're in the 1000+hp range. below that.. useless. but at that point you are using an external gate / gates or you're a tard who is trying to make crazy power on an internal gate haha

[Croustibat]

I think the OP is talking about that kind of elbow (which sucks)

http://www.dnamotoring.com/dsg/listing_images/ELB-SR20-T1.jpg

[Mikester]

I think the OP is talking about that kind of elbow (which sucks)

http://www.dnamotoring.com/dsg/listing_images/ELB-SR20-T1.jpg

^^THIS^^

+1 they SUCK... the design is horrible. Best way to get optimum performance out of a bottom mount is a nice, wide-open "big mouth" elbow. This is EXACTLY why you don't see them in the "reputable" companies' lineups ;)