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Can I Drill Holes in My Catalytic Converter?

Can I Drill Holes in My Catalytic Converter?

Just because you can do something doesn’t mean you should.

The catalytic converter in modern automobiles is part of an integrated system that affects everything – it’s connected to numerous computers, chips and sensors throughout a vehicle.

Not only will the electronics not like it but drilling holes into the catalytic converter could negatively affect performance.

It will certainly cause pollutants you can’t even smell to leak out into the environment and into the passenger area of the vehicle causing you and anyone else in the vehicle harm.

Which is why it’s against Federal law to mess with your catalytic converter.

Emissions Regulations

A catalytic converter’s job is to effectively reduce emissions. These are the fumes and gases that an automobile creates when it’s running.

Emissions contribute to air pollution, which is why the U.S. government amended the Clean Air Act by including the National Emissions Standards Act in 1965.

Many states have regulations that adhere to these federal standards.

Which is why if you live in one of those states, your state government requires that every registered vehicle must have its emissions output evaluated every year.

The Catalytic Converter

A catalytic converter is an important part of an exhaust system in an internal combustion engine. It’s part of a handful of parts designed to control emissions.

Although the first production catalytic converter was created in 1973, it didn’t become widespread until two years later.

A catalytic converter uses a chamber called a catalyst to change compounds from those fumes and gases into safer gases, like steam which is safer for us and the environment.

A catalytic converter is that hexagonal, rhombus, trapezoidal looking thing connected to the rest of the exhaust system on the underside of every passenger vehicle with an internal combustion engine.

In summary: Noxious emissions come into the catalyst from its input end connected closest to the engine. A chemical reaction breaks apart the pollutants turning them into safer emissions before being expelled through the output end connected to the muffler.

How the Catalytic Converter Works

As useful as the catalytic converter is to minimize pollutants, it’s restrictive when it comes to horsepower.

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Warning: Here comes an over generalization. The way an internal combustion engine works is by sucking air into the combustion chamber through the intake.

The combustion chamber is the internal part of an engine where air gets mixed with fuel to create combustion (or an explosion). These mini explosions force pistons down which is what causes the forward or reverse movement of a car, truck or SUV.

The byproduct of these explosions is toxic gases and fumes. They find their way out of the combustion chamber through either a stock exhaust manifold or aftermarket performance headers.

One area where exhaust gases must pass through as it snakes its way through the exhaust system is the catalytic converter.

The catalytic converter is where horsepower gets robbed.

A catalytic converter needs time to clean those toxic gases coming from the combustion chamber before they’re allowed to pass through the rest of the exhaust system and out the tail pipe.

The bad gases get cleaned through small-honeycombed openings in the catalytic converter. But the catalytic converter can only support a finite volume of gas at a time.

And until those gases are cleaned, more gases can’t come out of the combustion chamber. Which means more oxygen can’t go into the engine for the next combustion and this is what restricts horsepower.

This restriction is called back pressure.

Drilling Holes in a Catalytic Converter

The reason why people drill holes into the catalytic converter is to relieve back pressure. Drilling holes into the catalytic converter allows the bad gases to escape into the atmosphere before it’s been cleaned.

Those bad gases not only escape into the environment. But they also seep into the passenger compartment of your vehicle where you and your occupants breathe them in which can cause respiratory problems.

One reason why people resolve to drilling holes into the catalytic converter is to make their vehicle sound louder.

Keep reading to find out other ways people try to make their ride sound louder that’s not so good, along with better ways to make your car sound more aggressive.

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Driving a Car Without a Catalytic Converter

Another way people attempt to make their vehicle sound louder is by removing the catalytic converter all together.

But as you should already know by now, this creates as many problems as drilling holes into the catalytic converter. Removing the catalytic converter does the same job as a straight pipe.

Bypassing a Catalytic Converter with a Straight Pipe

Also called a test pipe, bypassing the catalytic converter with straight pipe is illegal for road use because it causes you to fail all emissions tests and smog checks.

That’s why they’re reserved for race use.

Remember, a catalytic converter’s primary job is to convert an engine’s harmful gases and fumes like carbon monoxide into less harmful emissions like carbon dioxide and water vapor.

Even if you live in a state that doesn’t require emissions testing, driving without a catalytic converter is illegal in all 50 states.

Not only that but if you ever need exhaust work done, most reputable mechanics won’t touch a vehicle that’s had the catalytic converter altered.

Making Your Vehicle Louder Without Drilling Holes into the Catalytic Converter

But if the reason why you want to drill holes in your catalytic converter is to make your vehicle sound louder. There are much better ways to do this:

  • You could increase the bore of your exhaust pipe. This allows cleaner exhaust to come out than what you get from drilling holes in the catalytic converter, and it creates a louder sound.
  • Installing a cold air intake makes your vehicle sound louder. A cold air intake works by allowing a denser amount of oxygen to flow into your engine. Since this system is less restrictive than a factory airbox, it sucks in more air into the engine making the engine sound louder.
  • You can add an exhaust tip. Exhaust tips come in various sizes to fit over a vehicle’s tail pipe. The wider diameter allows more exhaust gases to exit the exhaust system quickly making your car sound louder.
  • Replace your muffler. A muffler is designed to absorb as much exhaust noise as possible to make your vehicle as whisper quiet as possible. Replacing the factory S-shaped muffler with a straight muffler will make your vehicle sound louder.
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How to Fix a Clogged Catalytic Converter

Remember we said that the catalytic converter is plugged into a lot of other systems in a vehicle.

Which means that if it’s clogged up, not only will you get warning lights. But it could cause your car to shut off randomly – I had a Camaro like that once.

Signs of a clogged catalytic converter include:

  • slower performance;
  • reduced acceleration;
  • the smell of rotten eggs;
  • dark smoke coming from the tail pipe
  • and reduced gas mileage.

Unchecked, a bad catalytic converter will eventually damage your engine. Your best option for a clogged catalytic converter is to replace it.

But if you’re not in a position to do that another option is to try cleaning it.

There are catalytic converter cleaners on the market designed to reduce carbon build up. They’re not only formulated to clean the catalytic converter. But they’ll also clean the oxygen sensors, fuel injectors and cylinder heads.

They’re safe on gasoline, diesel and hybrid engines.

Or you can remove the catalytic converter and pressure wash it with a degreaser to get it unclogged.

Things That Damage a Catalytic Converter

Since a catalytic converter isn’t mechanical in that it doesn’t consist of moving parts. It’s one of the few areas on a car most of us would expect to have problems.

If properly cared for a catalytic converter will last as long as the vehicle. But therein lies the problem.

Again, a catalytic converter is tied into many other areas of a vehicle. So, damage to it is often a symptom of an issue coming from somewhere else.

Maybe the engine hasn’t been tuned up in a while. It could be a bad spark plug or spark plug wires. Perhaps oil or antifreeze entered the exhaust system. A damaged catalytic converter could simply be the result of a bad oxygen sensor.