So what really is the difference between the n/a and t2 tbs?

well lets start off by stating that the t2 tb is basically an upside down n/a tb. besides the obvious position of the tps and throttle cable mount, there really isnt that much of a difference between the 2? WRONG

having an old ported n/a tb i decided to see if it could be some use to the t2. i carefully inspected both tbs and found out that the primary butter flies open in the opposite direction. the t2 primary butterflies open downwards while the upside down n/a open upwards. let me further elaborate.

text pics too lazy to use paint

diagram of airflow from tb to uim plenums

( ) = intake plenums
>^ = airflow
/ = n/a tb butterly in opening position
\ = t2 tb butterfly in opening position



n/a
( )
^
^
> /


t/2
( )
^
^
> \ turbulence?


it clearly shows that the way the butterflies open on the n/a tb primary side, the one winged butterfly side which is the one with only one hole in the tb, moves the air TOWARDS the intake plenums which means less restricion and better throttle response. the t2 tb, on the other hand, moves the air away from it and could cause some turbulence.

so why go through all the trouble modding the tb? because throttle response is king on a rotary!

will it work? whats your opinion? im still a noob at this rotary thing...

ive already searched this up and found nothing.

 

85 views and not one comment? lol

 

TII's have throttle response?

you're overthinking things. i threw a simplified n/a throttle body on my TII and noticed no difference.

 

haha! yes they do! i mean even if its a small difference then it may be worth it.




ok heres the t2 uim... see how the intake plenums go up meaning the air flows up?




here is the t2 tb. see how the top/primary hole opens downwards away from the intake plenum? wouldnt that cause slight wind turbulence?



now here is the n/a tb. the butterfly would cause the air to move upwards TOWARDS the plenums instead of downwards away from it.


probably make a slight difference like the tb mod just wanted to share this for anyone that wants to improve throttle response. i installed it today and tested it out and FELT a difference.

 

The throttle body plate is in the exactly the same position during wide open throttle, I don't see how it makes a diference. If it is during part throttle operation, which you illustrated, you would need some very thorough test equipment. Like plotting acceleration g-load vs % throttle from an exact rpm and identical environmental conditions. My point being that the butt dyno is very deceiving. Especially so when you have a conclusion before going into the test. I remain very skeptical.

 

I don't doubt that you felt a difference considering there is a direct link to the throttle valves via the cable. Changing to a throttle that is slightly different mechanically is going to feel different. If changing that increased your personal enjoyment of the vehicle, that's great.

However the turbulence aspect (tumble flow really) for WOT performance is pretty minor. The air doesn't behave like you think it does inside the intake manifold. You are thinking that the air flows through the throttle body and into the engine. If that airflow could be smoothed out it may improve performance.

It's actually a lot more complicated than that, and the fact that the runners curve upward isn't that important. Mazda has actually written extensively about this...

 

well i will agree that switching to a non turbo cable over the mushy pedal feel of the turbo cable, that itself gave me a great impression of better response. unfortunately that was still with the modified turbo throttle body...

all it wound up being was a more solid pedal interaction and not any better response at all, just a more enjoyable feel working the pedal without any play in it any longer.

 

i think being under boost is gonna be the biggest factor.....its getting crammed in there...its moving so fast turbulence doesn't matter at all its in and out of the car in seconds

 

yes it is at the same position. i noticed the difference when i would just slowly accelerate instead of opening her up right away. i dont have dyno sheets or all of that fancy equipment but i know that its easier to get air from flaps that is facing you rather than away from you.

i did however did suck from the uim while opening the butterflys from the 2 tbs and noticed that it was easier to suck while using the n/a tb




yeah i noticed that the t2 throttle cable gets kind of annoying cause of its length. ill probably switch to a n/a one soon.

maybe im over thinking it haha

point is if you want slight throttle response from slight acceleration use a n/a tb =]