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Discussion Starter · #1 ·
would it be over kill to run a 70mm throttle body tapered to 68 on my ls/vtec.

my set up:
11.9 CR
type-r intake manifold
Skunk2 Stage 1 Cams
DC 4-1 Header
hi-flo cat
Greddy Sp-2 Catback

im planning on getting the RPM one featured on the an-r site.

opinions...?

thanks
 

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speaking from an engineering perspective, you have a pretty high compression ratio, which means more than just compressing the air/fuel ratio. The increase in compression generates more vacumm. I'm not sure what the stock size is on a B16B throttle body. I'm not sure either what the cam lobe and duration is, but this will also increase the air that is drawn in.....so in my mind these two factors together illustrate the possibility of a larger throttle body. I would say that 68mm would be fine, if you go to big the power you get probably won't be until the high end, because the is an optimum pressure in the chamber that will deliver and sustain power. If you go hella big you're not gonna feel shit because you will have lost the optimum vacumm within the chamber. think of it this way..... if you put a huge 4 inch tube on a vacumm that oringally had one with 1inch there will be too many places for air to escape within the cavity, because there is a increased amount of volume.

But to give you a short answer 68mm-70mm should be fine.......
 

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MichaelPal said:
would it be over kill to run a 70mm throttle body tapered to 68 on my ls/vtec.

my set up:
11.9 CR
type-r intake manifold
Skunk2 Stage 1 Cams
DC 4-1 Header
hi-flo cat
Greddy Sp-2 Catback

im planning on getting the RPM one featured on the an-r site.

opinions...?

thanks
Run it. Just make sure that you have the ITR intake manifold port matched to the throttle body's diameter.
 

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Thing is, 70 mm tapered isn't *that* big of a deal. I mean, it is but it isn't. Take a look at the Spoon TB.
 

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-=Zeqs=- said:
Thing is, 70 mm tapered isn't *that* big of a deal. I mean, it is but it isn't. Take a look at the Spoon TB.

still wont do any good if it cant get the air through the intake any faster... either because its more restrictive upstream or down... just like exhaust, the whole thing needs to be replaced as a system to maximize gains
 

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I'm running somewhat similar setup as you and the response is better from mid to higher range of the rpm...not to say the response is bad on the low end but it is a bit slow (Marginal difference - compared to high end gain), But my cams are CTR complete with retainer and springs with ITR header on a straight through system.
 
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