Port & Polished TB

Written by Rob Tuesday, 27 October 2009 17:00

Porting the 3.5L V6 Throttle Body

Porting and polishing is one of the easiest *free* horsepower modifications you can do. You can estimate at least 5HP and maybe up to 10 depending on a few things, like your CAI, fuel, etc. The entire goal in this is to increase the amount of air coming in. More air = more horsepower.

First, lets remove the air intake and the throttle body itself.  You can see instructions on that over here.

The upper entrance is exactly 70mm. So we want the entrance of the intake to be 74mm, with 2mm being removed all around the opening, tapering to the middle where it is 68mm. On the outer exit of the throttle body, the stock size is 68mm, but we want to open it up to 72mm.

Don't grind any area near the butterfly. Just leave it where it's at. Just taper TO it.

What tools will I need?

• Pneumatic or Electric die grinder
• Carbide Cutting Bits (cylinder with round tip works best)
• Flapper wheels or Sanding cones (80 grit, 120 grit)
• Caliper (for measuring diameters to check for accuracy and consistency)
• 500 grit, 1200 grit, polish compound, 2" cotton rag buffing wheel (for polishing....optional)

Here is the throttle body in it's stock form.

You'll see quite a bit has been taken out. This is past the rough cut.

Here we needed to take a bit more off the top to get it to 74mm.

Here is the top in the (almost) completed state. It just needs the finishing polish by hand. Look at it compared to the stock photo. This will let in a lot more air.

Here is the bottom before it was rough cut.

Rough cut.

I don't have a picture of the bottom final product, but there was a lot of polishing with the flapper wheel- I started at 80 grit, and then to the 120 grit, then a lot of hand sanding with 500 and 1200 grit sandpaper.

Once you are done, pull fuse #11 so the computer can reset and start over to relearn.

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