its late, and im crunchin #'s. correct me if im wrong in these calculations
the stock throttle body is 46mm in diameter a bored t/b is 55mm in diameter
using the radius and the formula Pie*radius squared this is what i get. 46/2=23, (23*3.14)squared is 5,215.7284 or 52.1 cm of space that air can be sucked into the intake manifold.
55/2=27.5, (27.5*3.14)squared is 7,456.3225 or 74.56 cm of space that air can be sucked into the intake manifold.
I cant wait til mine comes back from afx. and I figure that the gains will increase from this mod if it were to be done on a turbo car because the room for air thats gettin pushed into the engine from the turbo has opened up several squared centimeters.
anyways, im done. let me know what yall think, and yeah. i dont remember who had dibs on my t/b after i swap in the bored one, but speak up.
tia
03 srt-4 13.130@112.47mph (n2o, stock turbo, 10/2003) now: 20g, portfueler, bpu+++ (track/dyno times tbd...) i farted on your wiki
#11303, "RE: bored t/b added airflow" In response to Reply # 0
WOOOHH! Vegas, lay off the buds bro!! That shit hurt my brain!!! stock diameter is 52mm, Howell bores them to 55mm which is the same diameter as the intake.
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#11305, "RE: bored t/b added airflow" In response to Reply # 6
it is my understanding that the stock t/b is 46 mm. maybe thats's the stock butterfly, and its really 52mm, but the smallest part of it is where you have to do your measurments from.
im all about efficiency, and when im turboed, if i can cram in an extra 10-20 cm or air into the engine w/lbs of boost, i figure it is a good thing.
tia
03 srt-4 13.130@112.47mph (n2o, stock turbo, 10/2003) now: 20g, portfueler, bpu+++ (track/dyno times tbd...) i farted on your wiki
#11306, "there is a reason for that "hump" in the throttle body" In response to Reply # 6
All 2GNT throtle bodies are 52 mm. Now, for manual trannies they are 52 mm where the throttle plate is, but thay have that hump. I think the auto tranny throttle bodies don't have this hump, but I might be mistaken. (it should be like this, see our powertrain description on our main site, under fuel injection on the document)
This "hump" is what is called the contoured bore in the off-idle area. I have seen this with a ford throttle body as well as ours (the ford throttle body might have been from an escort ZX2, it was almost all plastic, I've looked at my throttle body when I had it off for the manifold install). This contoured bore makes it so at part throttle, not much air gets in at first. This makes it easier to launch the car. The progressive cam the throttle cable is hooked to also does this.
#11307, "RE: there is a reason for that "hump" in the throttle body" In response to Reply # 8
Noth AT and MT TB's are the same.. i've seen both.
That was my suspicion as well: The the hump is ther to reduce jumpiness in the throttle at part throttle operation.. Yet another way to reduce performance on a stock vehicle
I took my entire hump out with a metal rasp bit in a power drill. I always thought that it performed better at both part throttle and WOT after the fact.
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#11311, "RE: there is a reason for that "hump" in the throttle body" In response to Reply # 12
dam I knew somebody was going to say that, I was just kinda of disapointed of just a small gain. I bought the greddy header and I'm still waiting to see that gain, but at least that made my engine bay look alot better than that stock heat shield. hundred bucks is a hundred bucks, and now by seeing the numbers worked out a little bit I guess I'm not interested for the time being. I'll wait for the boost...
#11312, "RE: there is a reason for that "hump" in the throttle body" In response to Reply # 13
Porting the TB helps with throttle response off the line, also since our engine in stock form doesn't like to pull hard above 6500 rpm due to not enough air flow, opening the TB to a larger size allows the engine to receive more air and make more power up top. There is even more to be gained by porting the stock intake manifold. After I did this the car would pull hard to 7200rpm with no hesitation AT ALL! }>
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#11313, "RE: there is a reason for that "hump" in the throttle body" In response to Reply # 14
did you port your stock intake manifold with a dremel fast420a?? If so how did ya do it, ya know a lil write up. I could use my dad's dremel to bore it out
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stock diameter is 52mm, Howell bores them to 55mm which is the same diameter as the intake. 
