Straight Piping On Diesel Engine: Horsepower, Sound & Cost

By February 22, 2022Exhaust

Straight piping a diesel means deleting emission controls such as catalytic converter, resonator, O2 sensors, and muffler – to increase the exhaust airflow of your truck.

Straight piping comes with different key benefits such as better fuel economy, back pressure reduction, and better exhaust flow which allows gasses to pass without any restriction. People enjoy straight pipes on diesel trucks because of the sound it makes.

I have done straight piping on many vehicles before but my first diesel vehicle was a Ford F-150. During that time I was excited to see the results, it went well and my experience with straight piping a diesel was good. But like myself, many other people would be wondering how it is to straight pipe a diesel for their first time. But don’t worry, in this blog, I’m going to tell you how straight piping a diesel works and what are the actual benefits.

We will discuss:

  • What is straight pipe exhaust?
  • Is straight pipe Good for diesel?
  • Does straight piping a diesel increase HP?
  • What does straight piping a diesel do?
  • Will straight piping a diesel make it smoke?
  • Sound of straight pipe on diesel
  • How much is it to straight pipe a diesel?
  • Does straight pipe hurt your diesel engine?
  • Things you should consider before straight piping

What Is Straight Pipe Exhaust?

A straight pipe exhaust system means that there are no filters in the exhaust system which creates air restriction. A true straight pipe exhaust doesn’t have any Catalytic converter, Muffler, Resonator, O2 sensors, or DPS.

What comes to your mind when you hear the word “Straight pipe?”.

A long straight pipe, right?

Most people get confused when they hear about straight pipe exhaust. They think of a single straight piece of pipe coming out of your engine. To understand a straight pipe exhaust let’s have a look at the regular exhaust system of a diesel truck.

As you can see the stock exhaust system has different parts such as a catalytic converter, particulate converter, and muffler. These parts are called emission controllers and they are monitored by different O2 sensors located on the exhaust system.

Exhaust gasses go through each of these filters before leaving the exhaust pipe. These filters act to restrict the airflow in the exhaust and create back pressure.

When all the filters are removed and exhaust gasses go directly through the pipe, it’s called straight pipe exhaust. When exhaust flows smoothly without any backpressure, the engine can take more air through the intake and can generate more power.

Straight pipe exhaust directly affects fuel economy, improves it, and delivers more power as compared to the stock restricted exhaust system.

Is Straight Pipe Good For Diesel?

Straight pipe improves performance for both diesel and gasoline engines. It removes Cat, Muffler, and other components from the exhaust system causing Air restriction. When there is no restriction in exhaust flow the engine will feel more alive.

Straight piping a diesel is a good thing and the process includes removing emission controller components such as catalytic converter, resonator, and muffler – from the exhaust system. Due to these components, the exhaust airflow is restricted, and the engine can’t function at its best because of the backpressure caused by the stock exhaust system.

Your truck will thank you for doing straight pipe, especially if it’s an old diesel truck. Straight piping is one of the easiest modes that you can do to increase the performance of your truck.

You can get great power output from straight piping combined with basic modes like Aftermarket Air intake. 

Does Straight Piping A Diesel Increase Hp?

A straight pipe can increase the horsepower of diesel up to 5-10HP. Cheap Straight pipes can only add 4-5hp, as compared to expensive Straight pipes they weigh more.

As we all talked about better exhaust flow above, it makes sense how diesel can gain horsepower with a straight pipe exhaust.  A cheap straight pipe can only add 4-5hps because they are not good at holding boost while a good quality straight pipe can increase up to 10 Hps and even more depending on your vehicle.

I would recommend you install a Performance Air intake if you are looking for a performance boost in your stock truck. I did this so that I can get maximum benefits of better exhaust flow and straight pipe.

RELATED ARTICLE: Performance Air Filter On HP Gain.

What Does Straight Piping A Diesel Do?

Straight piping reduces back pressure

Straight piping a diesel removes DPF, Catalytic Converter, O2 sensors, resonator, and sometimes the muffler from the exhaust system. Performing straight pipe on diesel Improves engine life as well.

Why do you need all this stuff off from exhaust? Well as we already know that the main reason for doing straight pipe is to get rid of all the air restriction which is happening inside the exhaust system. Straight pipe means better exhaust flow and better flow means instant performance boost….

Straight piping reduces back pressure from your truck and also reduces the weight of your truck, and we are talking about serious weight here.. 20lbs approx or maybe, even more, depending on your vehicle.

One more key benefit of straight piping your diesel truck is better fuel economy. 

If you are doing performance modes then straight piping your truck would be the very first thing you’ll do to your truck – It’s a very basic and important mode.

After straight piping your truck you will feel a slight increase in horsepower and a major increase in performance of your truck. The straight pipe makes a diesel sound raw and beast, for some people it sounds like heaven.

RELATED ARTICLE: Muffler Delete Vs Straight Pipe: Horsepower, Mileage & Damages

Will Straight Piping A Diesel Make It Smoke?

The black smoke you see coming out of the diesel truck is not caused by a straight pipe. There are a couple of different reasons that could make a diesel truck smoke. For example, the black smoke indicates that the fuel is not burned properly or there is some serious problem with your engine. White and blue smoke also indicates problems with a bad engine.

The reason for smoke coming out of diesel trucks is not really simple. There are a couple of signs which indicate a different level of engine problems. Black smoke, blue smoke, and white smoke, each type is caused by different engine failure.

  • Black Smoke = Imbalance In Air Fuel Ratio
  • White Smoke = Improper Combustion
  • Blue Smoke = Engine Oil Buring

Here’s a YouTube of explaining Diesel Engine Smokes:

Small puffs coming out of a diesel truck are normal and they are expected after straight piping because you have already removed emission controlling features from the exhaust system of your truck.

Meanwhile, few people want their truck to smoke… Strange right?. Yes, it’s a strange thing to hear but there are so many people who make their truck smoke on purpose. A specific tune or mode called “Roll Coal ” is done to make your diesel truck smoke like a Train….. By adding extra fuel which goes unburnt through the exhaust and comes out in the form of black smoke, people make their truck smoke which is not recommended at all. Not only is it illegal but it also makes your MPG very poor.

Does Straight Pipe Exhaust Make A Diesel Sound Louder?

The Straight pipe exhaust definitely makes your diesel truck sound louder, in fact, this is the reason why most people install Straight pipe exhaust. Straight pipe exhausts are known and commonly used for making vehicles loud. There is no other exhaust mode that can replace straight piping in terms of making your vehicle loud. 

We have talked about performance improvement, fuel economy, Engine health, and much more but here is one more reason for installing a straight pipe on diesel which is making your truck louder.

A true straight pipe is a combination of Cat + Muffler delete which is the loudest straight pipe mode you can get. However, the straight pipe can be less loud if it’s being used with a muffler.

Does Straight Pipe Mean Fuel Waste?

A straight pipe does not affect fuel consumption or MPG. Fuel wastage is directly proportional to the bad combustion and imbalance air-fuel ratio – both reasons are not caused by a straight pipe.

Technically there is no reason for that – as long as you are not running any performance custom tune. In fact, the straight pipe might increase your fuel economy as compared to the stock exhaust system because good exhaust flow helps the engine with producing power without wasting any fuel.

RELATED ARTICLE: Do Mufflers Increase Horsepower: An Expert Weighs In

How Much Is It To Straight Pipe A Diesel?

Straight piping a diesel would cost you around 500-600 and could go up to on an average of 1500$.

Getting a good quality straight pipe exhaust is expensive and it comes with its own benefits. The good quality straight pipe can handle hot exhaust airs and it doesn’t need maintenance as often as compared to a cheap straight pipe. The pricing could be different for each vehicle and also for the area you are living in.

1000-1500$ is an average cost of a good quality straight pipe exhaust system but these are not the final figures. You can take these figures way higher if you are going with a full Titanium exhaust system.

DIY Cost To Straight Pipe A Diesel?

DIY Straight pipe cost could be as cheap as under 200$. DIY saves the cost of labor and expensive pipes which makes it cheaper than standard straight pipe cost.

You can DIY your diesel truck all by yourself if you know how to weld and you have all the tools required. All you have to do is remove the existing exhaust pipes from your truck and replace it with custom-made straight pipes. You have to weld the flange on both sides of your straight pipe pieces to mount it to the engine exhaust manifold.

If you can’t do straight piping all by yourself then I would recommend you seek the help of a professional guy and this will charge you a couple of extra bucks as labor cost.

Does Straight Pipe Hurt Your Diesel Engine?

The straight pipe doesn’t hurt the engine. A straight pipe exhaust enhances engine performance. The engine can be hurt because of Air restriction inside the exhaust system and the Straight pipe exhaust increases engine life span by removing exhaust restrictions.

We have already discussed how the straight pipe exhaust is good for diesel and how it helps in better exhaust flow, fuel economy, engine performance, etc.

If you are considering straight piping your diesel truck and you are afraid whether it’s good for your engine or not, I would say go for it.. Don’t worry, the straight pipe doesn’t hurt your diesel engine at all, instead, it will help the engine to live a bit longer…

Is Having A Straight Pipe Illegal?

Technically having a straight pipe exhaust is illegal because it makes excessive noise. Straight pipe falls in the category of exhaust modification which is also illegal because it is considered tampering with exhaust emission control.

Each country or state has its own laws for car noise. States like California have a strict rule for having a loud exhaust. A new law of California says that “If your vehicle is louder than 95dbs then an officer can fine you with a ticket”.

If you are running a true straight pipe without Muffler or Cat then the chances of you getting a ticket are way higher.

What Should I Consider Before Straight Piping My Diesel Truck?

  • If you are not willing to deal with a loud sound, then don’t do straight piping. It’s really important to look at whether you can or can not handle loud sounds. In some countries, straight piping is considered to be illegal due to the violation of noise law. So before making a decision please check your country or state laws correctly.
  • Straight piping your truck might sacrifice a bit of your comfort while driving. You will feel vibration beneath the truck if you are going with no muffler straight piping – exhaust is not muffled and it will ultimately make a vibration.
  • Don’t go for cheap DIY straight piping, I would never recommend doing this and there is also a reason behind that. Cheap straight pipes are made with low-quality material and get really hot. They also get damaged easily and it would be a pain to pay labor costs again and again.

Final Thoughts: Should I Get A Straight Pipe Exhaust For My Diesel

There is no doubt that straight pipes are beneficial for engine performance but having one on your vehicle is subjective.

If you can handle the loud sound of straight pipe exhaust and the laws in your area are not strict then there should be no issue in having a straight pipe exhaust system on your truck. Straight pipe exhaust is fun and it sounds cool.

However, if you have either strict laws or have difficulties with having a loud exhaust then I would suggest you don’t go with a straight pipe exhaust.

Also keep in mind that it might sound cool but having straight pipe exhaust on your daily drive is a bad idea. You can’t take that loud exhaust everywhere with you and you’ll be getting tickets on top.

Chai WJ.

Chai WJ.

I am a car enthusiast and a passionate rider who loves to discover new places. Since the pandemic, I can't go to places and I started to blog and share information that I learned. I'm not easily distracted, I just... OMG, do I hear a Supra?

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