Hollowing Out A Catalytic Converter – Full Guide

Hollowing Out A Catalytic Converter – Full Guide

Hollowing out a catalytic converter is illegal in some states because of its essential role in the environment.

The catalytic converter functions like an oven, trapping exhaust heat and using the heat to convert dangerous compounds to less harmful forms.

How to hollow out a catalytic converter

But, despite the environmental benefit, the catalytic converter impedes the vehicle’s full potential.

And this has led people to opt to take the risk of gutting out their catalytic converter.

So, if you are one of them, you are reading the right article as it provides you with the complete guide on how to gut out a catalytic converter.

Pros And Cons Of Hollowing Out A Catalytic Converter

There are numerous benefits when you hollow out your catalytic converter, and there are also some disadvantages.

A list has been made to provide you with a balanced review of hollowing out a catalytic converter. And they are:


The Sound Of The Exhaust

Hollowing out a catalyst converter changes the effect of the gases released from the engine during fuel combustion.

You can say that it is like removing the muffler from your car because the catalytic converter stifles the sound of the exhaust.

And, the sound becomes louder and more powerful; some people find this cool.

Generation Of More Horsepower

When you hollow out the catalytic converter, your vehicle’s horsepower can increase depending on the model of your car.

It is possible because the gutted catalytic converter creates a source of back-pressure on the engine.

It uses constriction to impact the exhaust gases before they are expelled with added speed from the car’s system.

And this improves the efficiency of the engine since there is less obstruction to hold it back.

Lower Temperature

Most people will not appreciate this because they do not understand the significance of low temperature to engines.

The catalytic converter’s presence makes the engine work extra to generate power, which leads to more heat.

But, hollowing out the catalytic converter eliminates this extra work and reduces the operating temperature.

Also, friction and load are eliminated, reducing the tendency of wear and tear.

Better Gas Mileage

The more the engine work, the more fuel it will consume.

And that’s why hollowing out the catalytic converter improves your car mileage which is very economical for you.


Unlike many other operations in your vehicle, hollowing out a catalytic converter is comparatively easy for you to do.

And this is an advantage because it does not require you to spend money visiting a technician to help you fix it.


It Is Illegal

Hollowing out a catalytic converter is prohibited in most U.S. States, and there are guidelines that you must follow to remove it legally.

And this can be very tedious and tasking to do for some people. The guidelines were initiated through the 1986 rules by the Environmental Protection Agency.

So, when you are caught violating the law, a severe fine will be issued to you, and they might prevent you from driving for some time.

Damage Your Vehicle

Hollowing out a catalytic converter might go haywire when you trigger a fault code in your vehicle.

And your car’s engine check light will illuminate on your heads-up display. And you might end up getting a false alarm from the warning light from time to time.

Though you can figure your way around this issue, there is a high probability that it might not return to normal.

Environmental Concern

There is environmental concern when hollowing the catalytic converter because of the emission of unconverted gases.

And this can cause other health complications aside from headaches. And it propagates the discussion about global warming, ocean acidification, acid rain, etc.

It also can impact humans directly when the gases are inhaled.

More Noise

Hollowing out a catalytic converter can lead to too much sound that can be offensive to some people.

The sound could be as high as 110 decibels which is way above the 85 decibels benchmark for safe sounds.

And it can drown the voices of people that are having conversations around.


Some leaks can occur after gutting out the catalytic converter due to broken parts when hollowing the catalytic converter.

These broken parts can create an opening where gas and air can be leaked.

And the way you can identify a leakage is through loud echoes, hissing, or vibrations when you start your car.

You can fix this problem with the help of a cold weld epoxy.

Hollowing out a catalytic converter

Method 1: Hollowing A Catalytic Converter By Removing It

Tools Needed

  1. Two-floor jacks: used to lift the car off the ground
  2. Wrench: use to screw the bolts
  3. A vice: to hold the exhaust firmly
  4. Respiratory protection: to protect you from inhaling the platinum as it pours out
  5. Crowbar: used to gut out the converter
  6. Hammer: used to hit the crowbar to gut out the converter

Step-By-Step Guide

Remove The Catalytic Converter

The catalytic converter is attached to the exhaust located under your vehicle. And to remove it, you will have to lift the car using two carjacks.

Then, use a wrench to loosen the bolts and detach the converter from the exhaust.

Gut It Out

Hollowing out a catalytic converter requires a vice to hold it together while using the crowbar and hammer to gut it.

But ensure that you have respiratory protection to avoid inhaling the catalytic substance.

Position the converter correctly facing upward, and then place the crowbar on the honeycombed core and hit it with the hammer. Ensure that you do this gently.

You can reverse the converter’s position to eradicate the core.

Reinstall The Catalytic Converter

After removing the core, you can place the converter into the exhaust and screw the bolt back in place. Ensure that it is tightened to prevent it from falling off.

Remove the carjacks and test the car. And, you should know that platinum can be sold or recycled.

Method 2: Hollowing A Catalytic Converter Without Removing It

Tools Needed

  1. Chisel
  2. Steel knife (putty)
  3. Air compressor
  4. Crowbar
  5. Grinding wheel (electrified) or Welding torch (ethane)
  6. Pneumatic lift or high frame jack
  7. Plier (broad-nosed)
  8. Arc welder (steel-wired)
  9. Fireproof goggles and hand gloves
  10. Cold weld epoxy
  11. Hammer (ball pen)

Step-By-Step Guide

Lift The Vehicle

Use the jack to lift the car and allow it to cool off before you start the process. It will prevent you from being hurt.

Locate The Converter

The catalytic converter is usually attached to the exhaust underneath your vehicle.

Bend The Cut Flap

Use a crowbar to bend down the cut flap, and be very careful not to cut it off entirely.

Then, use the wheel grinder or ethane welding torch to form a proper flap at the base of the converter.

Link The Seal Kit And Flap

Put on your welding goggles and gloves and use the arc welder to melt the steel wire. Then, use the putty steel knife to reshape the melted metal while still hot.

Break The Converter Covering

Use the hammer to break the honeycomb-like structure, but ensure that you do it gently to avoid damaging it. You can also use the chisel to help in the process.

Close The Flap

After removing the converter, you can use the plier to bend the flap back to cover the opening.

Enough strength will be required to do this, but be careful not to hurt yourself.

Weld The Flap

Weld the flap to seal the opening to avoid leakage.

Method 3: Using Test Pipes

Tools Needed

  1. Two-floor jacks: used to lift the car off the ground
  2. Wrench: use to screw the bolts

Step-By-Step Guide

Remove The Catalytic Converter

The catalytic converter is attached to the exhaust located under your vehicle. And to remove it, you will have to lift the car using two carjacks.

Then, use a wrench to loosen the bolts and detach the converter from the exhaust.

Install The Test Pipe

After removing the core, then correctly install the test pipe.

And you can use it to enjoy the benefit of a hollowed catalytic converter and, when necessary, re-fix the converter to avoid legal actions.


Hollowing out a catalytic converter is a risky business with the propensity to cause you some legal issues.

Except you have no intention of taking the vehicle out on the street, you can carry on.

It is an excellent feature to spice up your driving experience, especially the engine’s sound that draws attention. It makes it look like a worthy risk to take.

So, you can follow this guide to ensure safety when hollowing out your catalytic converter.