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How many lbs of boost can a Tial 38mm wastegate hold before one has to upgrade. The reason I am asking is I am buying a used kit, he was pushing 12lbs, I plan to run around 20. Going to upgrade turbo's down the road as well.

Current turbo is a GT40, plan to upgrading to a T72.

Thank you for your help.
 

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Correct me if I wrong but the amount of boost a 38mm will hold is based on what spring you put in the wastegate. A 12lb spring should hold 12lbs.

The time when wastegate size comes into play is when you plan on running a larger turbo with a lower amount of boost than normal. The waste gate has to be sized enough to allow the release of the amounted exhaust to keep the boost down. If the wastegate is to small and it can not flow enough to get rid of the unneeded exhaust you will get a higher than set psi
(boost creep)

So I believe runnin a high boost with the same wastegate is not a problem. You just need to get the right spring to set the psi or a boost controller.
 

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Correct me if I wrong but the amount of boost a 38mm will hold is based on what spring you put in the wastegate. A 12lb spring should hold 12lbs.

The time when wastegate size comes into play is when you plan on running a larger turbo with a lower amount of boost than normal. The waste gate has to be sized enough to allow the release of the amounted exhaust to keep the boost down. If the wastegate is to small and it can not flow enough to get rid of the unneeded exhaust you will get a higher than set psi
(boost creep)

So I believe runnin a high boost with the same wastegate is not a problem. You just need to get the right spring to set the psi or a boost controller.
He said he was upgrading turbos. :rolleyes:
Just use the 38, if you have issues...swap it out :)
 

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My T76 kit cam with a 38. I sold that and upgraged to a Turbo Smart 45. I really doubt a 38 will be able to control a T72 as well.

It comes down to how low you want to boost.
 

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Thinking 15 for the street and maybe 20-25 at the track. That is where I am worried.

Its the low boost levels you have to worry about :)

WG will start to shuts close for higher levels;) So size is less of a factor, at least that is the way I look at it.
 

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71swing
The time when wastegate size comes into play is when you plan on running a larger turbo with a lower amount of boost
speedy911
He said he was upgrading turbos
homank76
Thinking 15 for the street and maybe 20-25 at the track
I don't think 20-25lbs is low boost.
 

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i am running 6psi intially. so i bought a 60mm wastegate. (80mm turbo)
 

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i plan to boost it to 15 or so or higher. my rods/pistons are rated for 800. crank isnt. (650rwhp)
 

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no. it operates the same as a small one. its like they said. a big turbo needs to bleed a lot of exhaust for low boost, or to avoid overboost. that's all. if you dont need a big one then a big one is a waste of money.

my turbo is capable of supporting 25psi max. well if i am WOT and im driving the turbine too hard even with the waste gate open it will build boost. im only running moderate boost without race gas. my CR is 8.59. and besides my chasis isnt even in the solar system of being built for what the motor is capable of. so i have money to spend there over time.

with my wastegate (spring) set at minimum boost, ill be able to turn the boost controller low for daily driving and have good economy.
 

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what happens if you have a wastegate that is to big? lag?
You can't go to big on a WG. You can go to small though. The WG is one of the few areas where bigger is better.

I am running 2 38's on my 76, 352 setup. I can run 4.5 psi. That is as low as I tried. I'm sure it can go lower.

Like stated before, placement is also key to how it will work.
 
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