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Howdy, Im going turbo in a couple of months and I cant decide between an internal or an external wastegate. I am on a budget. I know the differences between them. But is it really worth it to pay for an external one? I know that you can make manual boost controlers for the internal wastegates. Which one is the way to go?
 

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An internal wastegate is built in as part of the turbocharger's turbine housing. It consists of an flapper door that allows exhaust gas to bypass the the turbine blade, thus regulating the amount of boost created. An external wastegate is a separate unit from the turbocharger, located on the exhaust header/manifold between the engine and the turbo. Regulating boost is done in a similar bypassing method, but is done before the exhaust gas reaches the turbochargers turbine housing. The size of an internal wastegate is proportionate to the size of the turbo, where as an external wastegate, because it's located outside of the turbo, can be made much larger. An internal wastegate becomes too small when the volume of exhaust gasses coming from the motor exceeds the efficiency of that size wastegate. That's when an external wastegate can be utilized, to vent the extra exhaust gasses to stabilize boost pressure.

So your best bet would be External !
 

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BoostControl on Sep/17/02 said:
An internal wastegate is built in as part of the turbocharger's turbine housing. It consists of an flapper door that allows exhaust gas to bypass the the turbine blade, thus regulating the amount of boost created. An external wastegate is a separate unit from the turbocharger, located on the exhaust header/manifold between the engine and the turbo. Regulating boost is done in a similar bypassing method, but is done before the exhaust gas reaches the turbochargers turbine housing. The size of an internal wastegate is proportionate to the size of the turbo, where as an external wastegate, because it's located outside of the turbo, can be made much larger. An internal wastegate becomes too small when the volume of exhaust gasses coming from the motor exceeds the efficiency of that size wastegate. That's when an external wastegate can be utilized, to vent the extra exhaust gasses to stabilize boost pressure.

So your best bet would be External !
If SMOG laws apply to you, external wastegates are a big no-no. They vent exhuast gas into the atmosphere, without the benefit of a catalytic converter. The only way you'd be able to pass a visual inspection is if you welded or bolted your wastegate dumptube back down into the downpipe.
 

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What is a safe boost level to run on a lower A/R T3 internal wastegate? Is 7psi ok for an internal wastegate on one of our stock 4 bangers (LS to be exact)? thanks. Also, would that mean that people with internal wastegates could use non-equal length turbo manifolds (b/c the wastegate is on the turbo instead of the manifold)? I've searched around and equal length manifolds are a lot more expensive than like revhard or drag. thanks.
 

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this is VERY informative...added to Common Topics.
 

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TurboLS on Sep/17/02 said:
What is a safe boost level to run on a lower A/R T3 internal wastegate? Is 7psi ok for an internal wastegate on one of our stock 4 bangers (LS to be exact)? thanks. Also, would that mean that people with internal wastegates could use non-equal length turbo manifolds (b/c the wastegate is on the turbo instead of the manifold)? I've searched around and equal length manifolds are a lot more expensive than like revhard or drag. thanks.
Excellent questions !
7psi is safe no matter which wastegate your runnig BUT..... !

Yes and no..."Equal-Length" gives you less chance of "Boost Creep" than say non-equal length...But only when using the EXTERNAL wastegate and it is centered and not say on runner 1. This is just a more efficent design and creates much better flow to the turbine.

It also has to do with what kind of wastegate you use...The Delgates that come standard with most kits tends to fail and cause boost creep...Although their Race-gate is an excellent design.

However...having an INTERNAL wastegate...of course your SMOG legal. BUT.....

As greater exhaust is put out...The internal wastegate actuators begin to lose their effectiveness because the amount of exhaust flow to be bypassed is now beyond their intended operating range. Because of more exhaust flow being greater than the valves capacity to discharge... So more exhaust flow is directed to the turbine and additional boost is created, which is called "Boost Creep". "Outlawed Boost" can now happen due to the volume of exhaust energy now being created. This is BAD...Nothing like :

"Whoa I set my MAX psi to 7 and all of a sudden I am hitting 10" ! Outlawed Boost Creep !!!
<--This can be controlled by an excellent Boost Controller such as the Blitz SBC-DC or the Apex-i AVC-R ! These units have what's called "Pass and Hold" – This is a safety function that allows the operator to set the amount of boost decrease in the event of any over boost. Warning is in both visual and audible.


So they each have their +'s and -'s another way to look it would be...The manifold and wastegate work hand in hand ! Manifold pushes the exhaust gases...Wastegate controls them or how much gets to the turbine.

Equal Length with a good Tial .35mm (or even bigger for you REAL DRAGGERS) wastegate is the ultimate "Race" setup ! For you Internal guys...Going with the Non-Equal length is quite ok...Just not my personal opinion for the best setup suggestion. But it works and your legal !

Long winded but I hope this helps..


P.S. I added this to our Turbo FAQ's !
 

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I would agree with boost control's point of view, but since most of us aren't going to be running more than a bar of boost anyway, without serious internal work, an internal wastegate will work fine. Many internal wastegates that are created, Like Mitsubishi or Garretts, have pretty high thresholds so that it if it is an 8lbs wastegate (internal) it is capable of venting over 15lbs of boost. Not bad.....
 

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Ya I have the same question, since the drag and revhard manifold are for external ones, do I have to get a manifold made or are there ones that I can bolt on, since I'd be using a t3 with internal gate.
Thanks!
 

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Discussion Starter · #14 ·
you should be looking for a b series turbo manifold that accepts a t3 flange. Make sure it does not have an external wastegate flange!!!
 

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I was looking at the GT25 (350hp) ball bearing turbos and the one I want has an internal wastegate. The only thing I'm wondering is how moch PSI the flapper can take? I mine as well get internal because...
1.Safer for environemnt.. passes smog but really doesnt relate to me
2.I dont have to buy a wastegate
3. The internal wastegate is made for the turbo unlike a universal external wastegate like tial.

I know the turbo is going to run around $1600 but if you think about it you mine as well get it. Its just water cooled so you don't have to run oil lines etc and it spools faster because its a true ball bearing turbo. Also the manifold will be more solid IMO because it won't need the flange. What do you guys think?

EDIT- NVM you still have to run oil lines but it takes less oil to lubricate the bearings.
 

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that's a good question that infamous stated, how much PSI can the flapper on an internal wastegate take before any signs of boost creep? i know 6-7 psi is safe but i'm planning on pushing at least 15 or whatever more my engine can handle but on an internal wastegate setup...i guess what i'm asking is do us guys who have the internal wastegate setup limited to the amount of psi we want to push vs the external wastegates? i do have the avc-r so someone mentioned that this was an excellent controller just for these boost creeps? does anyone else think otherwise?

last question is everyone is mentioning that if you have an internal wastegate, your smog legal...is that true? i mean don't you need the carb # for this...so far the only street legal turbo kit i know is the greddy...but i have a custom T3 turbo but with an internal wastegate...so does that make me legal? please enlighten me!! thanks TI! this is the best integra site!!!
 

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what I want to know is if the dump tube is directed back into the catalcytic converter does it affect the exhaust pulse that surferx talks about in his artcle on basic exhaust??
 

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SnakeRedRacing on Mar/03/04 said:
what I want to know is if the dump tube is directed back into the catalcytic converter does it affect the exhaust pulse that surferx talks about in his artcle on basic exhaust??
are you asking about the internal waste gate or external gates?

If internal, then yes, the exhast from the wastegate is returned to the gasses that actually pass through the turbo, and the angle and how smoothly they rejoin the flow before the cat can affect overall flow.
 
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