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Old 09-16-2021, 09:03 PM   #51
K3rm1tth3fr0g
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Quote:
Originally Posted by PotatoFlakeSTi View Post
The .83 AR got here last week, going on in a week or two.
I still think that you'll have enough back pressure to benefit from this if you are going all out.
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Old 09-17-2021, 12:30 AM   #52
silversurfer05
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Quote:
Originally Posted by PotatoFlakeSTi View Post
The .83 AR got here last week, going on in a week or two.
If you are going above 30 pounds of boost, you will probably see you nice big benefits. Under 25 pounds of boost I donít think this would help as much, but it would still help. Iím thinking about doing it as well to try and get the last bit of horsepower I can out of my set up before going six speed. (Currently 400whp @15psi spring pressure)
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Old 09-17-2021, 06:42 AM   #53
KillerBMotorsport
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In general the closer to the turbine exit, the bigger the reduction in backpressure and larger gains. Putting the valve near the muffler will have much less impact than say a hood exit at the top of the downpipe.

Quote:
Originally Posted by PotatoFlakeSTi View Post
I really want to do this, but also don't want to waste a bunch of money if I'm not generating enough backpressure for this to help. Hmmm!
Google search exhaust diameter calculator. There's a bunch of stuff out there, even for turbo stuff. It will give you a rough idea. Say for example, you're near the bottleneck point for 3", you'd get much bigger gains than if you were in the flow sweet spot. Also keep in mind the gains scale with power output.

Quote:
Originally Posted by K3rm1tth3fr0g View Post
Aren't you running a G30-900 on a .61 housing?

I imagine there is certainly enough back pressure for this to be beneficial.
With that, you likely have way high manifold pressure and less post turbine pressure because of it.

A G30-900 is going to have a BIG compressor and small turbine. That's backwards from what EJs like. EJs typically perform best with large turbines on a big A/R, and smaller compressors. For that turbo I would run the biggest A/R turbine you can find, especially if you're running E85 or race fuel. Small and medium turbines will chose the potential of the turbo. If these engines were like a 1.6 B16A from a Civic the argument would be different, but the EJ25 is actually large for a 4-banger and the better the exhaust breathes through the ENTIRE system, the better they perform. You'll also have better EGTs and improved low load transient response with a larger A/R
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