The turbos Ive selected have 4"vband flanges out on the hot side. What should I neck this down too? Is there a proper way to reduce?
406 cid sbc. Street car. Will have full 2.5 exhaust out the back.

 

What turbine wheel? There are some adapters available depending on the flange, or many just flare the pipe (or use a reducer) to match the v band size.

 

Specs.

• Intake: 4 inch
• Inlet: 2.5 inch
• Compressor trim: .70ar
• Turbine Trim: .84ar
• Compressor Wheel Inducer Diameter: 66.6 mm
• Compressor Wheel Exducer Diameter: 84.00 mm
• Turbine Wheel Inducer Diameter: 73.6 mm
• Turbine Wheel Exducer Diameter: 64.5 mm
• Thrust bearing: 360
• Actuator: Internal
• Exhaust outlet: 4" v-band
• Turbine Flange Type: T4 Flange

 

A 3" down pipe would be nice (using the 1.25 rule... 64.5 x 1.25), but you could probably sneak by with a 2.5- 2.75" depending on wastegate setup, and goals. It's a little strange that a turbine of that size has a 4" outlet, unless that's the od of the flange. Have a link to the turbo?

 

These were recommended by Forcefed86

[URL]https://www.ebay.com/itm/172719975224[/url]

 

I'd be trying to get a 3" DP on there. You can get a flange to bolt to turbo then neck it down to 3"

 

+1
I've used those turbos a bunch and always have just ran the vband to a reducer to a 3" DP.

 

I’d wait until you have the units in hand. I haven’t ordered that unit from the vendor, but the unit’s I’ve worked with that had similar housings/wheels are 3” Vbands. I’m guessing they may have measured incorrectly.

 

Ok this is a 3" flange on the turbos flange. Is there a 3.5 vband?

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Google answered.

 

My turbo was 4" to I went to my local napa bout 4"-3" adapter and used my 3" down pipe. I had cut and weld to get angles no pipe bender can do that "I tried" I work in a exhaust shop.

 

I believe that turbine wheel is a " P trim " , wouldn't it be easier to just buy a P trim 3" housing . No adapting and they are pretty common on ebay .

 

Im new to this but if that is true when I redo my down pipes next year in stainless I will be using those housings.

 

Here is an example of them, https://www.ebay.com/itm/Exhaust-ho...180976?hash=item4664857e70:g:jDAAAOSwi7RZLoG7 it comes with the housing , band clamp and adaptor flange 129.00, Mike

 

You can't count on anything Chinese being an exact copy. Most P trims i've seen are listed as/measured 74.2-74.5mm on the inducer, your listing shows it as 73.6mm. I believe there is a 3.5, or the gt45's are a 3.25" iirc.

 

Believe me I understand about the lack of quality on Chinese parts but I have had good luck with turbine housings . My turbo has a P trim ( 64x74 Turbonetics ) And I wanted to try a .81 T4 housing instead of my .68 so I purchased it for 89.00 and free shipping, works great and fit properly . I am still running it. I also have a couple 3576 T4 turbine housings I am using also

 

That's totally the op's call, but i'm just saying there's almost a full mm difference. A proper v band is simple, and no need to worry about it. Just my 2 cents.

 

Also, your 74, or 74.21 that Turbonetics claim is on par for the dimensions listed in the housing ad, if anything is odd, it's his turbine wheels.

 

Y

You are correct and before and after purchasing anything I check for proper fit . Every aftermarket part I purchase has to be modified in one way or another . I