throttle body size?

[fidel]

so i'm building a new b20 for my 142. its going to have a 92mm bore, 86mm stroke,11.5 to 1 compression, 46/38.5 valves, and a kg6 cam. i'll be ussing the long r-sport weber manifolds. i'm tring to figure out what size throttle bodies to use. my options are 40,42,45,48,50,and 55.
by looking at the r-sport and kg catalogs it looks like the minumum would be 48mm. i have not measured the manifolds yet but they look like they taper from 50mm down to size of the intake port.

does anyone have any expierence with twm, kinsler, jenvy, weber alpha throttle bodies?
they are all pretty close in price, very expensive. how is the quality on them?

another question would be injector placement. i have two options. one would be to use the stock location on the head ,witch would have the injectors spray directly on to the valves. the other would be to use the injector bosses in the throttle bodies witch would bring them farther back and would alow more fuel atomazation.?

third would be air horns. is there any way to get a ball park on lenght besides dyno testing.
from what i've seen long ones would give more mid low power were short ones would give better top end.

[BERTONE ALLEY]

I've wondered if size of TB is that important since I saw a B230 turbo that would produce 750hp w/stocksized TB. Can conclude size matters more on N/A motor w/length from TB to intake valve being most important.

Maybe this link can help;
http://www.bgsoflex.com/intakeln.html

[fidel]

so no one here has any expeirence with itb's?

[Dauntless]

I guess not many have experience. Anyway, I'd probably go with 48's in your application.

[WizuhD]

ITBs are not common, much less on turbo cars. however hondas/japanese imports use them a lot for great NA power, check out www.honda-tech.com the use them a lot on the h22/h23

gl

edit: webers have been some of the best for a LONG TIME ~50+yrs

[John V, outside agitator]

so no one here has any expeirence with itb's?
This IS Turbobricks.
Look inside the typical 45 DCOE and you'll see a 36 or 38mm venturi, look in a 48 DCOE and there'll be a 38 or 40 venturi.

Now most hot 2,0 rally motors, tuned for torque and a max bhp in the 6500-7000 rom range will have 48s if a guy has the money, and a 2300 should for sure be on 48s for carbs.

I would think that 45 or 1.75" ought to be just fine.

And the only injected motor with individual throttle bodies I have experience with was the 1995cc 16v Saab motor I built for Sam Bryan who won SCCA Gp2 (2 wheel drive-normal aspirated motors) Nation Championship back in 1995, so limited experience, but good.
We used 1.75" throttles and a manifold from Kinsler adapted to the Saab head.
215bhp at 7000.