Hi all,
Im converting my 12a turbo to FI this winter and am trying to piece together all that I will need. I am going to be using an IDA style 4injector type throttle body from TWM. My car is a 12a turbo stockport, and this is how the car will initiallly be tuned. However next winter I will be possibly converting to a 13b, or just staying with the 12a, but regardless the engine will be a half/full bridge port.
My options range from about 50mm to a 62mm throttle bores. I want to be able to tune a large amount of drivability into the car(more then my current 45dcoe, this is the reason for FI). I believe a 62mm is simply to big to be able to have off idle response and smoothness. 50mm seems a little to small, probally great for my stockport turbo at the moment, but when going to a bridge and shooting for around 400crank hp thats probally just going to choke things.
So in conclusion, i think a 55 is probally the best bet. Maybe a little bit of a sacrifice for topend power, but with the benefit of drivability.

What do you guys think??????
Please throw your opinions at me, theres alot of great knowledge in this section of the forum. Also thanks for taking the time to read this.
Thanks to all

 

48 or 50, the 48 would work best on the 12a application, but a 50 might be best for 13b

 

a 48mm or a 50mm will work good and have great driveability

 

smaller size = more intake velocity = better atomization of fuel, throttle responce and fuel mileage.

The 58 and up are used in full race only 13b peripheral ports.