A lot of posts on porting the stock TB lately, so figured I'd finally formalize a how-to on it. Very simple mod, about 2 hours worth of work depending on how far in detail you want to go, and cheap easy way to get nearly the same gains as a 400+ dollar SBTB!
Stock Un-Ported TB:
Stock throttle body is very rough finish, and has a HUGE casting nub on the inlet side. Very easy to see its not the most high-flow friendly piece. Also the TB blades have blocked off edges, and the TB screws are WAY longer than needed to be.
Tools Needed:
Dremel will do 99% of the work! Pic is flipped, so right to left is the order you'll use the bits.
1-2: Cone shaped & cylinder shaped grinding stones to make quick work of getting the casting nub ground down, & the cone one is great for knife edging the blades.
3-4: Big & small sanding disc cylinders. great for smoothing out the rough surface material in the TB bores, & smoothing over the grinding stones work.
5: Sanding flap disc. perfect for smoothing out the metal even more to a near shiny finish on everything from the bores, to the tb housing, to the blades, etc.
6: Cotton buffing wheel. for those that go above and beyond, throw in a little compound, & can buff the sanded areas out nice and shiny.
Blades:
-The brass material the blades are cast from is a bit rough, can smooth them out so they are a bit slicker, get any imperfections out, and knife edge the sides. just be sure you do NOT decrease the diameter of the blades. doing so may cause idling issues with more air getting by when the throttle is shut.
-Initial knife edging & smoothing with a grinding wheel.
-Intermediate finishing with flap wheel.
-Final polishing with compound & cotton wheel.
Throttle Bores:
-After grinding down the casting nub with the grinding bits, smooth out all the surface area with the sanding discs & flap wheel. on most TB's there's a small lip where the bores are cast through, can smooth out this transition so air flow in and out is a seamless flow.
-Can see in the first pic the TB bore hole on the bottom left has a small lip around the perimeter. Can grind this flat so the transition is smooth & seamless as in pic 2.
Screws:
-The stock screws are extremely long. There's two options at this point. If you dont plan on disassembling anything again, can grind the screws down totally flush, JB weld the threads, can even JB welt the transition along the shaft so its more aero-friendly, and even grind the screw heads down. The other option that I took, for if for some reason I ever want to disassemble the TB again, I left about 1 thread left on the screws for a little extra insurance they dont come loose, lock-tite on the threads, then center punch the back side of the screws to lock them in place. the screws are hollowed out so they punch easily.
-Also on the outlet I chamfered the edges a bit to smooth the airflow pattern out on each bore.
Finishing Touches:
-Final smoothing & polishing done. Didn't bother to go for a perfect mirror shine, but nice and smooth for air to flow over without creating turbulance.
-Completed! Painted the outside for a full finished look with Duplicolor Anodized Paints. Also left the very outter lip on the intake elbow side with the textured finish for a little "bite" on the intake elbow to reduce any chances of it popping off compared to if it was smoothed out. Doesn't affect air flow, so just a small tip to help hold things together better.
No go port your TB!