I have been planning on running a TWM 50mm (IDA type) throttle body on a downdraft intake on a large street ported 13B. I would prefer to not do a bridge port, since I would like some bottom end. For the most part, I generally just autocross the car.



Is this too much of an intake?

should be just about right, its a little bigger than a 48ida and should flow a little better as well

JEB, you going to custom make the downdraft?

Well here os the challange.

Most folks use 42 or 44 mm chokes in the IDA. This really drops the actual size of the port. a 50 mm throttle body will flow a good deal more than a 48 IDA (even a 51 IDA).

That is why I ask if it is too much...

Any amount of porting will put you in the Prepared class, so why not go ahead and bridge it? Or at least go half-bridge. That's what I run. Now I just gotta get tires so I can actually compete.

I run in a small club with liberal rules. I am pretty sure I can get away with a streetport, but a bridge or PP...no way.



On another note... Yes, tires make a world of difference!

I am running 710s on 8" wide wheels and my car finally sticks.