My only experience with them is on a RB26 so it relates a bit I guess. I'll explain it this way. Large single throttle body = BIG hp. Guys running big singles (think T88, T51R etc) on the RB go with a single large throttle body to aide in HP/ max flow. Most of the time these are dyno queens or drag cars.

Now, if you stick with twin turbos, say GT2860's like I had built.. and you want better throttle response you keep the ITB's. You loose a bit of peak horsepower but your tip-in response is lightyears better and with two smaller quick spooling turbos it makes the car much more fun to drive. The car still made 530awhp with ITB's so I wasn't complaining.

so we know that Turbo ITB combo is not unheard of, and that it helps throttle response but it hurts flow with a really high HP setup.......

question is....is it worth it.

should one go with a ITB's w/ a plenum or just say my idea/thought blows and one should go with a bad as Honda manifold and make it fit. possibly putting a bigger throttle body on.

One point of data is not proof, per the "hurts flow." Did you see my area calcs? Even small bike throttles give huge entrance area.

Also, ITB F1 Turbo engines make your point fail.

i was just doing a lil recap.

i think if i do this ill try to utilize 62mm TB's

Ok, if you put on ITB's with 62mm inlets, you'll be good for 1560 horsepower.

Not exactly what i'd recommend.

oh shit! NVM :bowrofl:

im bad at math....

whats good for 400 whp?

Hey, if F1 engines can do 1500 horsepower with 1.5L just imagine what your Miata can do with 1.8. :D

You should be fine using GSXR 600 throttles, they're 38mm, which is about the same as a 70mm single throttle body, which is good for about 500 horsepower. :)

fuck yeah, with my extra .3L of displacement! hehe

what is the measurement for our factory throttle-bodies? im gonna start looking at ITB's....

The factory throttle body is 48mm if i remember correctly, there's an upgrade from GoodWinRacing that's 60mm.

so 4 38 mm is = to 1 70mm TB

or is it

1 38mm is = to 1 70mm TB

38mm x 4 about equals one 70mm throttle.

thats what i thought, just checking.

what would be better, the 2 in one Throttles

http://www.epicwelding.com/auto_images/honda_itb.jpg

or 4 individual?

http://www.obxracingsports.com/produ..._image-711.jpg

Not sure exactly what you mean by "2 in one" but i'd go with one for each cylinder. That's what ITB's mean, after all.

Also, those big turbo cars? Willing to bet those are mainly drag cars, where throttle is either on or off most of the time. Throttle arrangement wouldn't matter there. Might be wrong, but that's the feeling i get.

EDIT: You just put up pictures, nice. It's not two in one, those are just different construction methods.

picks added!

2 in one meaning to separate TB's joined together

Edited my post, but it doesn't really matter in either case. :)

Tubes are tubes, doesn't matter how they're supported (as long as the support doesn't fail) as long as how the air travels is the same.

if it will be easier for me to go with 2 constructed together ill do that.


i just looked on egay. there is a set of GSXR 600 ITB's going for 110 bucks! most of them all range between 110 to 200 price range.

Just do make sure that you have your tuning method figured out before you start on the construction. Welding four tubes together and getting plates to turn is the easy part, tuning it is the hard part.

the ITB's wont get installed till after my car is back up and running and dynotuned. after that the ITB's will go on and it will be back to the dyno for tuning and comparing of the before and after.

See you're using MSPNP.

Will assume you're using speed density.

You may be able to get away with using the method i described earlier to get vacuum, but do make sure the people you take it to get tuned know how to tune for ITB's.

If I recall correctly the early 2000's (like 2000-2001ish) GSXR's have 2 paired TB's that each consist of two singles bolted together. This allows you to unbolt them and space them the same distance apart as the intake ports on the Miata head... making the manifold much easier to fab. The downside to that is some spacers need to be made and some fiddling with the linkage would also be necessary. Later GSXR TB's don't come apart... so be sure of what you're looking at.

Do a little google searching, it's how I found the info on which TB's come on which bikes.