education wanted: ddp, recirculated dp?

Koenigturbo

Active Member
Oct 4, 2006
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Why do you guys run a divorced/recirculated down pipe? I know the wastegate has it's own seperate pipe, but what the advantage? more power? more noise? Faster spooling what's the deal??
If it's more power then why do some of you guys/ gals run recirculated? to reduce noise? I don't get it.......help me learn something. "Go easy on me"::dunce::


Is a integural waste gate a disavantage?
 
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Guyana00

Droppin that JZ in soon!
Apr 18, 2007
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Divorced has a pipe for the wg, more flow, more power.

Recirc. is less noise. Divorced to atmosphere is loud at boost.
 

Koenigturbo

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Oct 4, 2006
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Guyana00;1409902 said:
Divorced has a pipe for the wg, more flow, more power.

Recirc. is less noise. Divorced to atmosphere is loud at boost.

seems to me that a recirculated system defeats the purpose of having an external waste gate.,if it goes back in to the exhaust and not the atmosphere, don't you get less power By having it go back to the exhaust?
Why have an external w.g. if your gonna recirculate it back in the exhaust.
 

gaboonviper85

Supramania Contributor
Jan 13, 2008
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Koenigturbo;1410081 said:
seems to me that a recirculated system defeats the purpose of having an external waste gate.,if it goes back in to the exhaust and not the atmosphere, don't you get less power By having it go back to the exhaust?
Why have an external w.g. if your gonna recirculate it back in the exhaust.

Divorced was the original idea too remove turbulance from the two gas exits so close too eachother...bic recircs the wastgate about two feet down which eliminates the turbulance so close too the exhaust turbine....the perform the same but one is quieter! Look at the stock turbo elbow and how crappy the wastegate area is (gasses hit a wall and then flow straight up in the path of the gasses exiting the turbo....this seriously reduces flow...then look at how bic recircs...far away from the turbo...much much better design!
 

Koenigturbo

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Oct 4, 2006
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gaboonviper85;1410094 said:
Divorced was the original idea too remove turbulance from the two gas exits so close too eachother...bic recircs the wastgate about two feet down which eliminates the turbulance so close too the exhaust turbine....the perform the same but one is quieter! Look at the stock turbo elbow and how crappy the wastegate area is (gasses hit a wall and then flow straight up in the path of the gasses exiting the turbo....this seriously reduces flow...then look at how bic recircs...far away from the turbo...much much better design!

O.K Then let me ask you this, I have a "Lipp" Elbow with a ct/26, aren't those two exhaust gasses right smack next to each other?? Isn"t that creating turbulance? I see your point about the two gasses causing turbulance.
RE: stock elbow: Maybe that was Toyota's way of straightening the air flow also making waste gate quieter, I don't know.
 

gaboonviper85

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Jan 13, 2008
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Toyota was just trying to make a cost effective system that was quiet and worked....working well is another thing:-(

Bic's design in theroy is much better...the math says so and math is never wrong! Now the question is will you feel the difference!? Yes the lipp elbow is better than stock but the gasses still collide at the elbow which is too close too the turbo!

I don't know exactly what answer you are looking for...? Recirc wastegates are fine aslong as it's done far enough away from the turbo to minimize turbulance at the turbo....divorced too atmos is just for people who want some wow factor...
 

Nghty89

Zombie Chicks Are Hot
Mar 26, 2008
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Also, just because a wastegate is external does not mean that it has to be circulated to the atmosphere. That is only done when you: A) Want a mean sound, that can also sound ricey at times B) Don't have an option to make an unrestricted pipe to recirc into the exhaust The difference between internal and external is only how efficient they are at certain boost/power levels, and where they are located. And just because it is open to the atmosphere, does not mean it will make more power
 

Koenigturbo

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Oct 4, 2006
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What kind of answer am I looking for??
The replys from you guys is the answer I"m looking for. I'm just looking for an education that's all. Just wondering why some people run ddp or recirculated, and what are the difference's, and is there a advantage to either one.
It sounds to me an external waste gate does't give you any noticable power, probaly not enough to make it worth my money.
Thanks everyone!
 

gaboonviper85

Supramania Contributor
Jan 13, 2008
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Koenigturbo;1410383 said:
What kind of answer am I looking for??
The replys from you guys is the answer I"m looking for. I'm just looking for an education that's all. Just wondering why some people run ddp or recirculated, and what are the difference's, and is there a advantage to either one.
It sounds to me an external waste gate does't give you any noticable power, probaly not enough to make it worth my money.
Thanks everyone!

Compared too stock it's well worth it!! I'd rather have a bic divorced downpipe that's recirc over a lipp elbow any day!
 

cjsupra90

previously chris90na-t
Jun 11, 2005
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Gaboon's answer to the Divorced is pretty much hitting the nail right on the head. The differance is although minimal on all but the most extreme power setups. Yes there is a differance, but it is minimal.

As for the Recirculate aspect with a divorced setup, as it was stated, its more for the wow factor then anything except again in the most extreme power situations. If joined correctly, the turbulance from recirculating the Wastegate dump back into the main exhaust is almost none.

As for external wastegates, they offer more precise boost control this is due to the size of the valve for one and its size relationship to the engine and exhaust flow and due to allowing the flow paths to be optimized through the exhaust manifold. The also eliminate turbulance in the inlet of the turbine. This is why a lot of turbos will suffer boost fluctuation once the gate opens on a internal setup. The hard 90* relief path that the intergate offers creates turbulance in the volute of the turbine housing thus slowing down exhaust flow to the wheel. If you were to video tape the wastegate actuator and arm on an internal setup while doing a long sustanined boost run, you would be surprised at the amount of movement and fluctuation that you would see (especially if you played it back at a slower speed)....
Again, like everything else, the lower the power production, the less you will notice the issues.
 

Turbo Habanero

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Apr 28, 2009
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Bic offers a great DDP and the option for it to be Recirculated. Throwing it on your car will get rid of the elbow completely and you will have much better flow making the stock turbo and waste gate to pull more boost and flow alot better.

As for the differences basically noise is the difference that you will notice.

And DDP is not emissions friendly unless its Recirculated.

Here is a video of a guys car on here with a Open BIC DDP

http://www.youtube.com/watch?v=_aR-mf3Qe34&feature=related
 

Reiketsukan

Jack of All Trades
Apr 13, 2009
288
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United States
When I bought my car, it had the stock turbo elbow and a cheapie Ebay DP on it. Recently, I installed a BIC DDP and a 3" test pipe. My turbo spools sooo much quicker now and it sounds freakin' MEAN when my wastegate opens. Just driving down the road I can hear my turbo spool up like diesel trucks on the highway, which I think is freakin' sweet. But... when I idle, my HKS Sport exhaust nearly as quiet as it was before, and driving down the road out of boost, there's just a slight 'deep rumble'.

The long and short of it is, it's quiet when you're driving normally, and loud when you mean business!! It fits like a dream and the workmanship is godly. You can even put the stock heat shield back on and be all 'stealth mode' under the hood if you like. If you have the $$ to spare, it's worth every penny, but you might find yourself needing another round of upgrades like me, since I hit fuel-cut now!

BIC FTW!!!!

:canada
 

Turbo Habanero

New Member
Apr 28, 2009
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Reiketsukan;1410686 said:
When I bought my car, it had the stock turbo elbow and a cheapie Ebay DP on it. Recently, I installed a BIC DDP and a 3" test pipe. My turbo spools sooo much quicker now and it sounds freakin' MEAN when my wastegate opens. Just driving down the road I can hear my turbo spool up like diesel trucks on the highway, which I think is freakin' sweet. But... when I idle, my HKS Sport exhaust nearly as quiet as it was before, and driving down the road out of boost, there's just a slight 'deep rumble'.

The long and short of it is, it's quiet when you're driving normally, and loud when you mean business!! It fits like a dream and the workmanship is godly. You can even put the stock heat shield back on and be all 'stealth mode' under the hood if you like. If you have the $$ to spare, it's worth every penny, but you might find yourself needing another round of upgrades like me, since I hit fuel-cut now!

BIC FTW!!!!

:canada

He is running stock Trim CT-26 tho so he shouldnt hit fuel cut
 

Turbo Habanero

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Apr 28, 2009
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Reiketsukan;1410709 said:
Duh... It's all good then, nab one if you can!!
:drink1:

He's looking for info i didnt want him to think he was going to hit fuel cut by throwing it on his car.

You didnt state anything about your setup so.
 

Reiketsukan

Jack of All Trades
Apr 13, 2009
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Turbo Habanero;1410716 said:
He's looking for info i didnt want him to think he was going to hit fuel cut by throwing it on his car.

You didnt state anything about your setup so.

No, it's all good! I had forgotten to mention that, so I'm glad you caught it!