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#bellmouth dp or divorced waste gate dp?

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PostPosted: Fri Jan 20, 2006 8:20 pm 
Fifth Gear
Joined: Tue Jan 25, 2005 9:14 pm
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Location: Twin Cities, MN
I'm not shure if they only sell complete TBE's or if you can get just a DP. It doesn't matter so much to me since I have to convert to a Garrett T25 flange anyway.

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PostPosted: Fri Jan 20, 2006 8:20 pm 
Fifth Gear
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"You're just a woman with a brain half the size of a man. It's science."

An interesting fact is sometimes turbulent flow allows for higher flow. After a while, molecules will build up near the surface of a smooth pipe.

I have the Invidia v3 with the 4 in bellmouth that goes to 3". I like it and have never had a problem with it but i have an external wastegate.

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PostPosted: Mon Jan 23, 2006 7:54 pm 
First Gear
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Location: Atlanta, GA
Bosal sells a good cheap divorced dp.

http://subydude.com/osc/product_info.ph ... 5d087b31ea

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PostPosted: Mon Jan 23, 2006 8:24 pm 
Third Gear
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Location: Vancouver, B.C.
That's a good price, and shows that competition is coming in :!: :!:

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PostPosted: Tue Mar 14, 2006 4:39 am 
Third Gear
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Location: WA
if im not mistaken, doesnt heat in an exhaust system, make it flow faster? all that friction creating heat would create a faster flow? ehh not sure if its correct but just wanted to add that. :smt119

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PostPosted: Tue Mar 14, 2006 8:46 am 
Fourth Gear
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Doesnt matter.

One will not get you more power than the other. There are way too many other factors at stake.

Unless your in high HP apps. In that case dump wastegate to atmosphere.

Ceramic coating and heat wrap makes soo much more of a difference.


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PostPosted: Tue Jun 06, 2006 7:14 am 
Fourth Gear
Joined: Mon Oct 27, 2003 7:17 am
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Location: Oahu, Hawaii, USA
So, how good is the bosal dp? How does it compare to the ces in quality of manufacture, fitment, and, of course, torque and hp?

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PostPosted: Wed Jun 07, 2006 12:28 am 
Third Gear
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Location: Mn
I've got the Bosal. I've never seen the CES system in person, so I can't really compare, but I'm very happy with mine. I bought mine used about a year ago for $170. The only fitment issue was that the tab that bolts to the trans doesn't line up, so I didn't use that. And of coarse, I had all new exhuast pipe ran from there back. I really prefer the open downpipe sound, though. :twisted: I just need to find a new tranny so I can drive it again. :evil:

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'94 Auto SS-vf24, WRX TMIC, Bosal twin dump, Meth kit coming soon!-Now RWD!


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PostPosted: Wed Jun 07, 2006 9:51 pm 
Fourth Gear
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Binford, can you describe the difference in sound with the bosal vs the open dp, please?

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PostPosted: Thu Jun 08, 2006 3:23 pm 
Third Gear
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I meant I prefer running with only the Bosal downpipe. Like saying open headers in V8 slang.

It sounds like a V8-Harley-w/turbo whine. :lol:

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'93 5MT N/A wagon, over 400,000 miles!-Gone, parts lived on
'94 Auto SS-vf24, WRX TMIC, Bosal twin dump, Meth kit coming soon!-Now RWD!


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PostPosted: Thu Jun 08, 2006 3:52 pm 
Fourth Gear
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Whoops! My mistake. Thanks for the clarification! :D

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PostPosted: Sat Jun 10, 2006 12:50 am 
Second Gear
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Interesting discussion...I see both sides, and I've taken fluid dynamics.... :-D

My thoughts, for the sake of the butt dyno, either will be a substantial improvement over stock. Divorced or bellmouth, I bet you would never feel the difference if one exists. I'd let my wallet make this choice. Cheaper bell mouth FTW :twisted:

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PostPosted: Sat Sep 09, 2006 2:49 am 
First Gear
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Location: Aurora, CO
Bump! I just had to bump this post that my friend told me he posted a while back. I just sold him my exhaust and was looking for some answers. I'll try to delete the topic I posted.

Seems like DWDP's or Twin dump are the best choice.

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PostPosted: Sat Sep 09, 2006 2:50 am 
First Gear
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Location: Aurora, CO
This should be a sticky as far as Exhaust and DP's go!!!

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Gold '88 Starion ESI-R (Drift Project)
Brgndy '92 Legacy SS, Agency Power Style Headers and Up-pipe (ebay, don't stay together), Underdrive Pully, 5MT conv, mod'd WRX cold air intake and short shifter, 12.5 lb fly


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PostPosted: Tue Sep 12, 2006 7:25 pm 
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Location: Aurora, CO
I've been looking around, and I think the best DP i found was the B&B DP. I found it for $318 with free shipping @ www.SuperExhaust.com It's a full 3" that eliminates the Pre-Cat and has a 1.75" wastegate pipe. Mandrel Bent. Stainless Steel. It also has a separator plate on the turbine side so there's no chance of it getting in the way of the wastegate. And every review I've seen for it gives it a perfect 5 of 5 stars!

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Yellow '01 Kaw. ZX-7R (SOLD) :(
Gold '88 Starion ESI-R (Drift Project)
Brgndy '92 Legacy SS, Agency Power Style Headers and Up-pipe (ebay, don't stay together), Underdrive Pully, 5MT conv, mod'd WRX cold air intake and short shifter, 12.5 lb fly


Last edited by createnew on Tue Sep 19, 2006 7:57 am, edited 1 time in total.

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PostPosted: Tue Sep 12, 2006 10:19 pm 
Fifth Gear
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Location: USA: Portland, OR (Tigard, ~200ft elevation)
createnew wrote:
I've been looking around, and I think the best DP i found was the B&B DP. I found it for $318 with free shipping @ www.SuperExhaust.com It's a full 3" that eliminates the Pre-Cat and has a 1.75" wastegate pipe. Mandrel Bent. Stainless Steel. It also has a separator place on the turbine side so there's no chance of it getting in the way of the wastegate. And every review I've seen for it gives it a perfect 5 of 5 stars!


You mean this one?

http://www.superexhaust.com/cgi-bin/boat/details?part_num=FPIM-1030&products=1&session_id=bbd9ea004bc045595bfedff5c762aea6

Looks like a great deal, but it's a little vague. Have you ordered and installed this piece? Does it have the correct turbo flange on it, and does it indeed have a divorced wastegate dump pipe? It shows it on the photo, but it also says "for illustrative purposes only" so I'm not sure.

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PostPosted: Wed Sep 13, 2006 3:38 am 
Fourth Gear
Joined: Wed Mar 09, 2005 10:04 pm
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I've got the crucial coated divorced DP in my basement ready to go on. Nice piece...

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PostPosted: Thu Sep 14, 2006 8:03 am 
First Gear
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free5ty1e wrote:
Looks like a great deal, but it's a little vague. Have you ordered and installed this piece? Does it have the correct turbo flange on it, and does it indeed have a divorced wastegate dump pipe? It shows it on the photo, but it also says "for illustrative purposes only" so I'm not sure.

It's definately a divorced wastegate. I've looked all over the internet and found the same pictures everywhere. There is one site that has about 6 pics of it. Just search for WRX B&B downpipe and you'll find a bunch of stuff about it. All the reviews I've seen are 5 of 5 stars. And the flange will fit. It's an IHI flange. I've had a WRX DP on my car before and it bolted up perfectly. (To the turbo, and the placement was right too.) I put it on after I already had a custom exhaust so I never got to see how it fit against the stock stuff.

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Yellow '01 Kaw. ZX-7R (SOLD) :(
Gold '88 Starion ESI-R (Drift Project)
Brgndy '92 Legacy SS, Agency Power Style Headers and Up-pipe (ebay, don't stay together), Underdrive Pully, 5MT conv, mod'd WRX cold air intake and short shifter, 12.5 lb fly


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PostPosted: Wed Feb 14, 2007 11:49 am 
Second Gear
Joined: Thu Jan 18, 2007 9:28 am
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Location: Vancouver, Canada
Quick question, if I get one of these dp's bellmouth or divorced wastegate and hook it up to my stock vf11, will it work when I upgrade to a td04? I guess what I mean is, do the two turbos sit in the same position once installed?

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PostPosted: Wed Feb 14, 2007 3:58 pm 
Third Gear
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know1 wrote:
Quick question, if I get one of these dp's bellmouth or divorced wastegate and hook it up to my stock vf11, will it work when I upgrade to a td04? I guess what I mean is, do the two turbos sit in the same position once installed?


Yes.

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'91 5MT SS-TD04, WRX TMIC, Bosal twin dump, Spec LW flywheel/pressure plate, FCD, Walbro fuel pump-RIP
'93 5MT N/A wagon, over 400,000 miles!-Gone, parts lived on
'94 Auto SS-vf24, WRX TMIC, Bosal twin dump, Meth kit coming soon!-Now RWD!


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PostPosted: Thu Jun 21, 2007 4:49 pm 
Second Gear
Joined: Mon Dec 26, 2005 12:53 am
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Location: Artic Tundra - MN
Can anyone tell me if there would be any fitment issues with the B&B downpipe on a TD05? Would i have to modify the divider that fits inside the turbo at all?

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PostPosted: Wed Feb 27, 2008 9:15 am 
First Gear
Joined: Thu Oct 18, 2007 8:28 am
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Location: Southern California
cobb has some info on their site
http://www.cobbtuning.com/info/?ID=3222
from Josh Tenny
Quote:
Flange w/Simple Pipe - The only advantages to this design are cost and simplicity. The pipe does not have to be formed and the flange is simple therefore reducing cost. The labor to weld the pipe to the flange is easy and therefore less costly as well. That is the main factor that make it desirable to the factory and why it is used on the stock exhaust. The wastegate gasses joining the turbo gasses right at the turbo outlet does create turbulence in the worst spot post turbo and reduces flow, thus not making it as desirable for performance as other designs.

BellMouth - This method is much closer to optimal for joining the gasses from the outlets. There is more room for them to join and if the transition is done properly it can flow very well into the main piping. It packages very well and does not have a lot of complexity, making for less to break. We have gotten the best results from this type of downpipe so far. Boost response has been the best out of the outlet designs we have tuned on, it is easy to put a wideband oxygen sensor bung into. We have also had the fewest problems with this design.

Split Bell Mouth - This design separates the gasses in the beginning of the turbo outlet and joins them at the rear of the bell mouth section. It works well and has some of the advantages of the bell mouth and some of the advantages of the divorced wastegate designs. The main deterrent for this is the cost and complexity of adding the splitter. I am a fan of keeping things as simple as possible while still making the product work well.

Divorced Wastegate - Keeping the gasses from the turbo outlet and wastegate separate until farther back in the system is an attempt to combine the advantages of not collecting the gasses and the real world. Combining them far back is closer to optimal than collecting them closer to the outlets. It is also critical to power production and spool-up to join the pipes smoothly and avoid turbulence. The disadvantages are that you add a lot of cost and complexity. You have big temperature differences on each pipe and that makes for a system that can crack. Putting in flex or expansion joints helps, but adds even further complexity and yet another part to fail. With all of the exhaust systems we have tuned with on the dyno we have seen that it is generally harder to bring boost on as quickly with these types of systems as compared to the bell mouth type systems. Perhaps it helps the wastegate function too well. Also, we have had a few situations where the splitter caused problems allowing the wastegate to function properly by not allowing it to open to its full extent, or even open at all. That caused either boost spiking, or no control over boost what so ever. Since the wastegate could not function the turbo ran as if it did even not have one, and the poor turbo just ran whatever boost it could make uncontrolled. The fix was not hard, but the least amount of stuff to go wrong the better. I know that I would not be happy having to pay for someone to install the exhaust only to have another place diagnose the problem, remove the exhaust, repair the part, and re-install the exhaust.

Cast Outlets - Castings have the advantage of keeping a lot of heat in the exhaust as well as freedom with design. You can basically make it almost any shape you want. The disadvantages are more weight and cost. Cast iron pieces can weigh a ton and that is a valid concern for many people. The casting form that the piece is made in is also very expensive and depending on complexity can range from a couple of thousand dollars to well up in the tens of thousands.

Formed Piping -Forming pipe has almost as much design freedom as a casting with less expense and less weight. The only disadvantage lies in if it is not done properly. Poor forming can look bad and effect flow by having creases and crimped spots. You can also get the piping too thin if you try to stretch the metal too far. If done improperly you can also make the metal brittle and it will usually happen where the metal is the thinnest.

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PostPosted: Mon Jun 09, 2008 5:29 pm 
Third Gear
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hello guy for the b&b i look and its said work for wrx is this work also for legacy 94 turbo

bcuz the next upgrade i am planning to do is a 3" set up
anyone can tell me the average price for a average setup. what mark ect...


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PostPosted: Mon Jun 09, 2008 9:01 pm 
Knowledgeable
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I've always wanted to hear what a car would sound like with a divorced system that has the wastegate tube completely open to atmosphere. You could run a second exhaust pipe to the rear/side of the car so the passengers arent poisoned.


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PostPosted: Wed Jun 25, 2008 10:27 pm 
Fifth Gear
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im looking for a decent downpipe... i think.

is this one legit?
here

or this one?
#2

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