ITB size question
 

Hi,

I'm looking into buying ITB from tweakit, and was woundering what would be a best bet for me the 50mm or the 55mm? This engine will be NA for about a year or so with this setup and then will be going with a centrifugal superchager. The other option i guess too would be tapered from 55mm to 50mm.

The engine that its going on too is a SP 12a.

Let me know thanks

i would also like to know what would be a good size (im goin for a similar setup but turbo instead of s/c) i'm currently leaning towards the 50mm (55mm seems too big for a 12a, plus it costs more)

before you do the tweakit kit, look at www.fuji-racing.com They finished their kit a few weeks back, and have had a lot of good reviews from the miata community. I know it comes with a weber lower intake manifold, and there are assorted other things that you get with the kit. I think Jimmy is the name of the guy I talked to there. he told me what came with but i dont remember it off the top of my head. Thats the route I plan on going in a few months.


BC

well alot of people are also recommending TWM but still need to know size :MissileSm

I think that you'll find with most ITB style manifolds being quite short, that anything larger than 48mm is going to hurt bottom end alot on a 12a. I would say 45-48mm on a 12a, 48-50mm on a 13B. Both streetports.

TWM have discontinued the 50 and 55mm IDA style TB. They have released the 56, 58 and 62mm IDA style TB's for the high horsepower rotaries. If you want anything smaller you will have to use a DCOE style type. You should not consider anything bigger than a 50mm TB for a mild 12A anyway.

Go to www.twminduction.com for more info.

Here's the 62mm complete with fuel rails and tps sensor.

http://www.twminduction.com/Throttle...s/62mm_ida.jpg

also another question, what would the tapered ITB feel like vs the regular one? So lets say you compare a regular bore size of just 48 vs one that goes from 52-50-48 size? Will that act more of less bigger than a 48, and will it hurt the low end performance more, or does it actually liven it up?

bump ... also I would like to know how's the drivability factor and power factor of an ITB vs FI 4150 Carb style manifold?