How to Bore a Throttle Body (3 Simple Steps)

Let us guess, you want better mileage and rev. For that, you’ve decided to bore your throttle body. Well, don’t look sideways. We’ve got you covered!

Boring your throttle body is completely optional. It wouldn’t get you any revolutionary change in your vehicle. But it sure has its merits though! Else we wouldn’t be here, would we?

So, how to bore a throttle body?


First of all, we’ll widen the front side of the throttle body with a rotary tool. Then we’ll do the same with the backside. After that, we’ll polish the whole interior as the final touch. Finally, we’re gonna use sandpaper to smoothen the surface.

Still in the fog about the whole process? Let’s move forward and complete boring your throttle body step by step.

Is a Bored Throttle Body Worth It?

Before we start boring right away, first figure out if you really need to bore your throttle body. Don’t worry, we’ll keep it short!

Let’s find out first the pros and cons of a bored throttle body. Then we’ll decide whether you should do it or not.


With a bored throttle body, your engine will get more airflow into it. This means you’ll get a better CFM. As a result, the engine will amplify its power output on your command of acceleration.

In short, the throttle response will be superior to stock performance. Also, you’ll get better mileage.

But how much more mileage or CFM you’ll get depends on the specification of your car. But whatever the model your car is, you’ll definitely get better performance than stock.


Every good thing comes with a price. In this case, because of increased CFM, you won’t be able to leave your vehicle idle for too long.

More CFM means more airflow and less idling time. The idling may get reduced by 2-3 minutes than usual based on the engine. But on the bright side, leaving your car idle is bad for it anyways!

So, should you bore your throttle body? Look at the pros and cons for yourself. So, what are we waiting for?

How Do I Bore a Throttle Body?

Now it’s time to get into business. We will follow 3 simple steps to bore the throttle body and experience a whole new ride!

Required Tools

To bore the throttle body, we’ll be needing some tools for this DIY project and they are:

  • A rotary tool and sandpaper grit
  • One assortment of sandpaper
  • Metal polish

Now that we have the equipment we need, let’s bore this damn throttle body!

Step 1 of 3- Grind Inside the Throttle Body

If you look at the throttle body from its upside, you’ll see humps around the butterfly plate.

Now to bring down the hump, we’ll be needing a rotary tool. If you don’t have any rotary tool at home, here are our best picks for you:

Now that you have your tool, equip it with a 60 grit wheel and start grinding the hump. You might need several grit wheels for this so get some extra.

However, it might get difficult for you to keep track of the round shape. You might not get it perfectly round. But maybe you could use your kitchen sink to keep track of it. You can also use any other perfectly round-shaped objects like a glass or cup.

After you’re done grinding the front side, take your throttle body to the sink, glass, or cup. Now hold the throttle body over it and compare the roundness. This way, you can spot the difference if there is any, and level it with more grinding.

After you’re done with the front side, it’s time for the backside. You don’t have to do anything additional. Grind this side too just like the front side and measure the shape. Get rid of the humps if there are any. 

The backside will take a little longer time due to the thickness of that part of the body. We suggest you use your rotary tool with frequent breaks. After using 4-5 minutes, give it a break for 2 minutes, and so on. Running it continuously could result in the rotary tool as well as the throttle body heating up.

Step 2 of 3- Smoothen The Surface

Now that we have taken care of the major work, all that’s left are some touch-ups. We’ll now smoothen the surface with sandpaper.

First, take 60 grit sandpaper and start sanding inside the throttle body. Then sand with 100 grit paper. Gradually move up to 220 grit.

The reason we’re gradually using an assortment of sandpaper is to avoid a rough surface. As we move up the numbers, it leads to a better finishing. It could get so smooth, you’ll feel like the inside of the throttle body is made of glass!

Step 3 of 3- Apply Metal Polish

This one is not a compulsory step. But it will help to some extent. Get a quality metal polish and apply it to the inner and outer surface of the throttle body.

It will give it a shiny look, protect it from creating oxides, and save it from rust.

And we’re done!

Frequently Asked Questions

Q: What are the symptoms of a bad throttle body?

Ans: If your throttle body is damaged, your car will have trouble accelerating. Also, the engine won’t idle smoothly. They are the basic problems that occur when the throttle body is failing.

Q: Can I drive without a throttle body?

Ans: If your car functions without a throttle body, you won’t need one in the first place. But if it functions with one, you definitely need a throttle body.

Q: What throttle bodies are made of?

Ans: Throttle bodies are made of Aluminum because it’s lighter than other long-lasting metals.


Here, you have your throttle body bored. You see, this was a very simple and cheap DIY project to boost your vehicle power. Now use it and see the difference for yourself!

We hope we’ve been able to help you with how to bore a throttle body. Don’t forget to let us know your new experience in the comment section.

Happy driving!

Rob Dahm

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