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Discussion Starter · #1 ·
I understand how they hook up. I dont fully understand how you adjust the boost with them. Do you have to change the springs inside to adjust the boost. Or are the springs just for a certain range? Whats a good size for a 3800? 38mm?

Thanks
Tye
 

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You can adjust them with springs or some form of Manual or Electric boost controller. Most gate companies will sell springs with a listed bar rating telling you how much boost to expect when that spring is installed in the wastegate. They aren't always acurate, but will get you in the ballpark. A boost controller is your best bet after you get your base spring installed. It allows for quick boost level change and fine tuning.

A 38mm gate will work fine if it's properly located.
 

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Discussion Starter · #3 ·
pimpiumz34 said:
You can adjust them with springs or some form of Manual or Electric boost controller. Most gate companies will sell springs with a listed bar rating telling you how much boost to expect when that spring is installed in the wastegate. They aren't always acurate, but will get you in the ballpark. A boost controller is your best bet after you get your base spring installed. It allows for quick boost level change and fine tuning.

A 38mm gate will work fine if it's properly located.
Thanks for the info. I assume they also use vacuum along with the springs since you can use a boost controller.
 

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external wastegate sizes depend on a lot of different factors...what kind of turbo, where is it being located, is it a log manifold or tubular, etc etc etc...my guess is either a 35 or 38mm wga...srt-4's with 500+whp are using 35 or 38mm...only reason to go to a 40 is if you have about 600+whp...

The way you control it is with a boost controller. Also, you want the wastegate to open up all the way at the VERY LAST second before redline...or before your car shifts under WOT condt's... Reason being is if it opens too early then your wasting all that boost and not getting the most out of the car/turbo setup. If it opens up all the way at about 2-300rpm's before redline then your using all that power and putting it all to the ground, and not wasting much if any of the boost.

BTW, if you externally dump it to the atmosphere (vs. dumping it into the downpipe) its 50 state ILLEGAL, and any inspection place can fail you wit ha visoal inspection...just an fyi...so look for a manifold that has the external wastegate dumped back INTO either the manifold or downpipe. Also, you'll want the wastegate to gather exhaust gases from ALL THE CYLINDER PORTS!!! not just 1 or 2...ALL OF THEM!!!...

Probably more info than you or anyone else needed to know but hey...better to live and learn the experiment and pay up the @$$ for repairs...
 

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I have seen a car pass emissions with an external dump and NO cat. Also the exhaust manifold was leaking. And yes it was is the 'burbs of chicago.
But it still would be a good idea to route the wastegate into the exhaust. Its kinda loud, but good for attracing some attention if you want to.
 

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how...

Um...how the hell would you pass emissions with an external dump...please inform me...my friend has Nissan 350Z twin turbo, and went for emissions for the first time and FAILED visual inspection cuz it was an external dump unit (GReddy TT kit). The ONLY WAY and I literally mean THE ONLY WAY to pass is if he did the OBD II check, it didnt throw any codes, and he did NO visual check and you just left after he said you passed...thats the ONLY way...uless you pay off the guy..like me!!! $$$$$$$$$$$$$$$$$$$$$!!!
 

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imxlr8in said:
jus curious why would it be whats the difference between that and the 38mm
46mm - 38mm = 8mm larger. I bet for your purpose you may be able to use a 38-40mm wastegate and never out-flow that size wastegate.
 
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