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Hi guys, i bought a garrett gt3582r as part of a turbo kit for my r33 gtr with the .82 rer housing. The turbo i have comes with the 2.5inch 4 bolt exhuast outlet. I have noticed the gt3582r also comes with the 3 inch v band exhuast outlet. Does this 3 inch vband actually just taper up to 3 inch and offer better performance or is the outlet actually bigger than my turbos outlet?

Edited by asps91
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Best turbine performance/efficiency is achieved by the biggest pressure drop across the turbine.

Consider that the distance from turbine blade to the 4 bolt flange face is ~50ish mm, and that measurement would not vary significantly whether you are talking 2.5 or 3 inch outlet. The diameter of the outlet will be the same at the exit of the turbine rotor, so the difference is the rate of expansion available over 50ish mm to where the exhaust dump pipe bolts up. I'd suspect the difference won't be enough to be concerned about in most instances.

Sure the 3 inch outlet version should be a technically better option, but the question is what are you using the car for, what is the target power output (airflow considerations), and what dump pipe design are you using? 4 inch dump is a pretty massive thing that might pose difficulties in fitting all the pipework into available space. 3 or 3.5 inch will perform very well and far easier to fit down past the firewall.

I'd be making sure that your dump uses a shoulder section to give rapid size change from the turbine outlet to whatever dump pipe diameter you choose. That should assist with ensuring best pressure drop across the turbine.

im looking to make close to 400kw on e85 through my rb26. The 4 inch dump fits up perfectly. The cars going in for a tune tommorow and was not sure if i was wasting my time with the turbo i have. I rang GCG turbos to find out about a to4z compressor wheel conversion and they told me not to bother with the 2.5 inch exhuast housing as it just wont make the power but i found it a little hard to beleive as i had a feeling the outlet was the same at the wheel on the 3 inch v-band and the 2.5 4 bolt. This confirms it :)

Asking GCG anything is possibly not the best idea.

You could easily get that power from a 3 inch dump if you are talking about an externally gated setup. I doubt the turbine outlet size is a worry.

The T04R wheel that gets used in those "GT35/T04Z conversions is not exactly a modern wheel and I think a decent billet compressor would do better .

You could have a V band adapter machined up and welded to your housing to create a 3" or larger outlet on the same cone angle as the housing .

A .

Asking GCG anything is possibly not the best idea.

You could easily get that power from a 3 inch dump if you are talking about an externally gated setup. I doubt the turbine outlet size is a worry.

Yea, ive gathered that haha. I am externally gated ;) Cant wait for the tune tommorow!

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