Basically I'm just curious if a larger aftermarket TB would affect driveability negativley. Is it possible to go too big? does it depend on the size of the motor? What kind of gains could be expected? Thanks

 

yes

 

could you explain why?

 

yes... too big and it won't match your intake manifold. it's a pointless upgrade unless you have some head work (like upgraded cams), and an intake manifold. i believe anything aftermarket will be too big.

 

Yes, it will kill your intake velocity....which kills off the ramming effect of incoming air. It will also make your throttle response and low end power bite the dust as well. From what I've seen a 62-64mm is perfect for upwards of the 220whp mark....past that and you might go bigger, but anything bewteen 170-220 is going to be in that range and anything under 170 needs the stock 60mm.

 

It all depends on your setup/Tune.
Basically a throttle 68mm tb will compliment some good head work such as cams, porting and a larger IM
Ill give you an example
Im running a Built 1.8 Lsvtec with a 68mm TB
Buddys Running a built 2.0 Ls Vtec with a 70mm TB

with a stock B16/GSR you could pick up a few hp from a TYpe R TB or even porting the stock one...........
Like we say to the mustang guys bigger is not always better!