bellmouth dp or divorced waste gate dp?
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- 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.
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.
///M
'93 Legacy SS - part out
'93 Legacy SS - part out
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- Third Gear
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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.
I just need to find a new tranny so I can drive it again. ![Evil or Very Mad :evil:](./images/smilies/icon_evil.gif)
![Twisted Evil :twisted:](./images/smilies/icon_twisted.gif)
![Evil or Very Mad :evil:](./images/smilies/icon_evil.gif)
'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!
'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!
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.![Laughing :lol:](./images/smilies/icon_lol.gif)
It sounds like a V8-Harley-w/turbo whine.
![Laughing :lol:](./images/smilies/icon_lol.gif)
'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!
'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!
Interesting discussion...I see both sides, and I've taken fluid dynamics....
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 Evil :twisted:](./images/smilies/icon_twisted.gif)
![Very Happy :-D](./images/smilies/003.gif)
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 Evil :twisted:](./images/smilies/icon_twisted.gif)
Retired but still rocking a 98 Coupe with the heart of a turbo legacy :)
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.
Seems like DWDP's or Twin dump are the best choice.
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
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
This should be a sticky as far as Exhaust and DP's go!!!
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
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
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!
Last edited by createnew on Tue Sep 19, 2006 7:57 am, edited 1 time in total.
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
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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- Fifth Gear
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You mean this one?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!
http://www.superexhaust.com/cgi-bin/boa ... f5c762aea6
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.
-Chris
91SS 4EAT stock
91SS 5MT awaiting engine rebuild and VF36...
92SS 4EAT - RIP![Sad :(](./images/smilies/icon_sad.gif)
94SS 5MT4.11+rLSD 289k km: RobTune550,TD05-16g @ 18psi,FMIC,3"TBE,Forester lift
91SS 4EAT stock
91SS 5MT awaiting engine rebuild and VF36...
92SS 4EAT - RIP
![Sad :(](./images/smilies/icon_sad.gif)
94SS 5MT4.11+rLSD 289k km: RobTune550,TD05-16g @ 18psi,FMIC,3"TBE,Forester lift
I've got the crucial coated divorced DP in my basement ready to go on. Nice piece...
93SS 5MT White, TD05-16G, TMIC, 3"Turboback, Magnaflow, Alu Rad, H&R Sports, AGX struts, F/R STBs, Whiteline Sways, ALK+Endlinks, Odyssey 925, AC delete, Evo8 Recaros, Sparco 4p, 3.9 LSD, Hellas+air horns, IPD short throw, 99RSrims, s03's
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.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.
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
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
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?
1994 Crimson Pearl SS [ td04, 06 fxt tmic,3" catless dp -> apex GT spec exhaust, EDM Tails ]
Yes.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?
'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!
'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!
cobb has some info on their site
http://www.cobbtuning.com/info/?ID=3222
from Josh Tenny
http://www.cobbtuning.com/info/?ID=3222
from Josh Tenny
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.
94 AT FWD N/A wagon-gutted daily driver.
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