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Who makes the exhausts for MotoGP?

The evolution of the MotoGP exhaust system has taken some 30 years to get to where it is today.

While most of us are familiar with the name Akrapovic let’s have a look at how this brand became the favourite among the MotoGP teams enjoying a 30 year relationship with MotoGP and supplying over 75% of the MotoGP, Moto2 and moto3 grids with exhaust systems.

logo akrapovic

Who are Akrapovic?

Akrapovic began with Slovenian Motorcycle racer Igor Akrapovic and has been manufacturing exhaust systems since the 1990s.

While in the beginning it was only racing motorcycle exhausts, it has since expanded to include mainstream road bikes and car exhaust systems.

With proven success in WSB and other racing sectors in 2002 when MotoGP changed formats to the 4 stroke engines, Akrapovic moved in as supplier and since then has been a favourite among the teams both factory and satellite.

Akrapovič enjoyed its first premier class win in 2011 followed by its maiden MotoGP Championship a year later, and again in 2015. All three were achieved by Jorge Lorenzo on a Yamaha.

Akrapovic not only supplies the systems but is also a technical partner to MotoGP continuing to work closely with teams and manufacturers.

In 2022 we saw 17 out of 22 riders choose Akrapovic and now in 2023 Honda Racing has joined the ranks by switching from SC-Project to Akrapovic.

How important is the exhaust on a MotoGP bike?

Joan Mir MotoGP Exhaust

Image courtesy of Box Repsol on Flickr

In MotoGP, exhaust systems are designed to extract maximum performance from the engine. The exhaust system’s design is critical because it impacts the engine’s power output, torque, and throttle response.

A well-designed exhaust system can help increase the engine’s horsepower and torque, allowing the bike to go faster and accelerate quicker.

MotoGP bikes use four-stroke engines that require a specific type of exhaust system. These engines are usually high-revving and the exhaust system needs to be designed to handle the high RPMs.

The exhaust system’s length, diameter, and the number of bends can affect the engine’s power output. The longer the exhaust system, the more torque it produces, and the shorter it is, the more horsepower it produces.

What are the MotoGP regulations re Exhausts?

The rules in the FIM MotoGP sporting regulations for motorbike exhausts are as follows.

You will notice they are quite vague and not strict, this allows manufacturers a little leeway in their exhaust development. They can also choose between a single and twin.

Regulation 2.4.3.7 Exhaust

1. The outlet of the exhaust must not extend behind a line drawn vertically through the edge of the rear tyre.

2. For safety reasons, the exposed edge of the exhaust pipe outlet must be rounded to avoid any sharp edges.

3. Variable length exhaust systems are not permitted.

4. Exhaust Gas Recirculation (EGR) systems are not permitted.

Do MotoGP Bikes Use Catalytic Converters and Mufflers?

As with everything in MotoGP it comes down to weight. The lighter the bike the faster it goes. So, anything that adds weight without increasing performance is not used.

A catalytic converter will add extra weight to the bike and significantly reduce the engine’s horsepower output. It also creates unpredictability as it heats up and changes the output. And not in a good way for racing

MotoGP also do not use mufflers in the same way road bikes and cars do.

The piping is created in a way that reduces the harmonics that are emitted. This can drop the decibel level down from 128 dB to the 115 dB that we as fans have come to love over the years.

How do MotoGP exhaust systems differ from street bike exhausts?

Akrapovic exhausts are made from titanium alloy and can withstand temperatures of over 900 degrees Celsius.

Due to the incredible pressure and heat within the specially designed pipes they are held together with special plates machined from something called Inconel – a nickel chromium super alloy.

This prevents separation of the pipes during the race.

Both of these materials are machined under strict conditions on a 5 axis CNC machine. Computerised Numerical Control machining provides the ability to manufacture complex parts from very strong, durable materials such as titanium alloy.

The method of machining and joining the pipes together means they can withstand pressures above 5bar and forces of more than 50kgs.

In contrast, standard road bike exhausts are usually made from less expensive materials like steel or aluminium, which are heavier and less durable.

Alternatively, carbon fibre if you want something stronger that does not heat up (as a pillion this is important)

MotoGP exhausts are also designed to be highly customisable, allowing teams to fine-tune the exhaust system to extract the maximum performance from the engine.

The length, diameter, and number of bends in the exhaust system can all impact the bike’s power output, torque, and throttle response.

In contrast, standard road bike exhausts are not highly customisable and are designed to meet emissions.

Another significant difference between MotoGP and standard road bike exhausts is the sound they produce.

A MotoGP bike’s exhaust system is designed to be loud and distinctive, contributing to the overall racing experience.

In contrast, standard road bike exhausts are designed to produce a relatively quiet sound to meet strict noise regulations.

To put this in a real world perspective, the maximum noise level from a MotoGP bike is 130 decibels (akin to a jet taking off) whereas for the road bike, the maximum is 80 decibels (akin to a noisy restaurant).

The road bike noise regulations do vary around the world and 80 decibels regulation is for Europe.

Why do MotoGP Bikes have Mesh on their Exhausts?

You may notice MotoGP bikes have a mesh covering their exhaust.

Joan Mir MotoGP exhaust mesh blowup

Image courtesy of Box Repsol on Flickr

The point of this mesh cover is to prevent rocks and gravel from entering the engine via the exhaust in a crash.

Most crashes end up in the gravel traps, which are there to slow the bikes down and prevent serious crashes into barricades trackside.

Why do MotoGP bikes have two exhausts?

While teams can choose between twin and single, many teams in MotoGP use a twin exhaust system.

This depends on the type of engine configuration used and how they want the power delivered.

Let’s have a quick look at the 3 main types of twin exhaust configurations that can be used on a MotoGP bike, these are:

  • Two exhausts on the side
  • Two exhausts under the seat
  • One exhaust on the side and one under the seat
Joan Mir MotoGP Exhaust Configuration

Image courtesy of Box Repsol on Flickr

The regulations do limit the teams in a way by stipulating that variable-length exhausts are not allowed.

This makes it a bit trickier for a twin exhaust system as both sides must be of equal length and results in an extra bend being added on the other side to meet the regulations.

Twin or single exhaust. Which gives more power?

It is worth noting again that the power difference is not about the horsepower but how the power is applied to the rear wheel and this depends on how the bike is tuned.

Exhausts are all about the fluid dynamics and how to expel burned fumes out of the engine while creating the vacuum in the cylinder to suck more air in.

It is too hard to say which would create more power as each team has their bike tuned for ultimate performance.

How has the design of MotoGP exhausts evolved over the years?

In the early days of MotoGP racing, exhaust systems were relatively simple, with straight pipes leading from the engine to the muffler.

Over time, designers began experimenting with different materials, shapes, and configurations to optimise the exhaust’s performance.

One significant change was the transition from steel to titanium as the preferred material for exhaust systems.

Titanium is much lighter than steel, which helps reduce the overall weight of the bike, leading to improved handling and acceleration.

However as mentioned earlier, titanium must be cut and machined under strict temperature-controlled conditions and is a very complex metal to work with.

Another significant development has been the introduction of the “underbelly” exhaust system, which routes the exhaust pipes beneath the engine rather than out the back of the bike.

This design has several benefits, including improved aerodynamics, reduced weight and a lower centre of gravity.

Is a MotoGP exhaust road legal?

No most definitely not! The MotoGP exhaust does not meet the emission and noise regulations.

The cost would also make them unattainable for the average road user with Titanium and Inconel being some of the most expensive and difficult to cut metals available.

Road users also do not need to worry so much about weight reducing their speed making exhausts such as these unnecessary on the road.

 

And there we have it, MotoGP exhausts and their evolution over the last 30 years with Akrapovic, which shows no sign of slowing down any time soon as they march their way towards being the perhaps the only exhaust provider for MotoGP.

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