B series throttle body sizes?

[Chr1s]

I'd go 64mm and work the manifold slightly

[TODA AU]

My 5c worth of advice is for guys with basic to mild B-series builds is to stick to an OEM throttle & manifold.
This will not only deliver good results more easily, it’ll save you wasting money on products where your return on investment is poor.
For serious engine builds where maximum output is required…
I'm still yet to see a B-series with a plenum actually benefit from a using throttle any larger than 65mm.

For GSi_PSi I’d say keep your B16A intake manifold & use a 62mm ITR throttle or a Spoon one if you can get your hands on one.
You’ll need to sort out the entrance to the plenum too.

As for part throttle on a 68mm,
To be frank, on most B-series applications it is actually crap.
& again with most B-series applications the 68mm (or larger) throttle suffers from a lack of air speed…
This can be readily seen as a loss in power through back to back testing against smaller units.
Combined with low air speed, 100kpa (MAP) can be achieved with as little as 33% throttle application. (70mm throttles are even worse)
So the net result is a narrowing of the tuning resolution in most applications or necessitates the use of secondary tables & or TPS mapping.
Not an issue for some, but bothersome in any case. Particularly when the benefit is difficult to even measure if not justify.

On another note, what aught to be said is the intake length & diameter is a lot more important than the throttle size.

[Chr1s]

To quote you quickly,

"on most B series applications it is actually crap"

I've seen kids here running 68mm throttles on a near stock B16A, no surprise.

[Aydin]

go with oem honda man just get a b18c7 (typr r) t/b there 62mm and there oem ive herd aftermarket t/b are sticky and after driveing the car a bit hard they get stuck and u lose driverbillity

[AXS]

go with oem honda man just get a b18c7 (typr r) t/b there 62mm and there oem ive herd aftermarket t/b are sticky and after driveing the car a bit hard they get stuck and u lose driverbillity

sticky, yes thats true but not as bad as it sounds, like all cars you get used to it and adjust driving according to how the car wants to be driven, i used a 68mm tb and 68mm ported intake manifold both skunk2 and running on a stock computer i have seen a really good torque gain and overall power...B20 you say? as iv seen your build tread you have some serious internals done id go with the 70mm Tb and port your IM to the same size, that way youl have a smooth transition of air, no restriction.

hope that helps!