Hey all for a street port motor what would you all consider the best TB size out of the following sizes:
3x45
3x50
4x48
4x54
The TB will go on a stock 6PI LIM with a custom UIM.

 

i was curious as to the 3x throttle body VS th 4x tb , would you get any problems the center tb sharing the 2 pri ports?

looking to do same project

 

That's what it does from the factory.

 

The 2 3x tbs are actually stock ones from and FC or FD.

 

Also for setting up a plenum in an N/A application is it better to have it before or after the TB? I noticed a few engines that live at higher RPMs, older F1 engines (not sure on current) and sport bikes, have the plenum after the TB.

 

No, the FD has 2x50mm and 1x45mm as far as I know. I've heard that the 20B has 3x50mm, but that might just be rumor.

 

i was imagining a itb set-up over the stock lower

 

It would work the same way if you used 3 ITBs.

 

I'd do 4x48, or 2x48 and 2x54 (primary/secondary, don't need to be progressive) and throw away the stock intake manifold altogether.

 

would those size plate be a little too big?