Infini IV

I will soon be building a full-bridge engine, but have not an idea of what size throttle bodies to go with.

The engine will be a mix of parts:
-12A irons
-GSL-SE rotor housings
-9.7 rotors

I will extend the ports up as far as I can go, but I will keep the bridge thick (5mm) as well as leave a decent amount of room between the water seals and the aux-ports.

I will also use the familiar IDA intake manifolds that you can buy anywhere. Not optimum, but what I'll have to use until I learn build my own intake manifold.

I want throttles that won't restrict where the motor wants to make power at, but at the same time, I don't want to go too big where it will be hell to tune. It will be run with a Microtech LT8s.

Rotortuner

Id go with a 50. Unless you drag racing and launching at 9k your going to be more happy with the 50. You will have betterlow end response and the 50 without any chokes is big.

CJG

Judge Ito

Im running dual 55mm throttle body. on a bridgeported 13B. making over 300 rwhp.. I would say. if your going to use 1 throttle body go with the 55mm

Infini IV

Thanks for the responses. It will be IDA-style dual throttles.

Hmm, so would the 50mm throttles be sufficient to get the motor the air it needs? If so, I'd figure it may be easier to tune than to go with the bigger 55mm throttles.

APEXL8T

I had TWM 55 IDA but it was on a monsta street port. Use a wide band to tune. I borrowed a base map and went from there. This was in 1993 .