Are Loud Pipes Ruining Our Sport?

Depends on who you ask

September 2007 Feature Arne Rantanen, Jr. Viewed 852 time(s)

Snowmobiling is constantly bombarded with negative press and anti-snowmobiling sentiments throughout the United States and Canada. It seems every day there is a new report detailing the negative aspects of snowmobiling. In almost all reports snowmobiles are described as loud, obnoxious and deafening.

In recent years all the manufacturers have made concerted efforts to reduce the noise output of snowmobiles, yet many consumers discard these efforts and choose to ride by the slogan "Loud Pipes Save Lives."

Are loud pipes ruining our sport?

Some arguments made by those who choose to modify their snowmobiles with a louder exhaust system are that their sled sounds too much like a vacuum cleaner or that the stock exhaust is too restrictive and robs horsepower. Others say they are trying to get rid of excess weight and gain extra room under the hood.

Many of these people are of the mindset that if it's louder then it must be faster. Some will say they are only looking to improve or enhance the sound a little bit, while others just want to "scare old ladies."  Whether you want "mental horsepower" or you prefer the relative quietness, you cannot ignore the fact that snowmobiles with loud exhaust systems are contributing to the closing of riding areas across the country.

Power Perception

The sound of something, particularly a motorized vehicle, can increase the perception of power in many people (take NASCAR and the NHRA, for example). But, because something is loud, does it mean that it is faster or makes more power?

Just by making something louder, be it a car, truck, motorcycle or snowmobile, there is no guarantee of an increase of power or speed. This confuses many people because they attend a snocross or hillclimb event and all the modified sleds are loud, therefore helping cement the relationship between noise and power in people's minds.

Racing snowmobiles are typically loud for one reason: weight. Racing is about going fast and weight doesn't help the quest for speed. Silencers add weight, which isn't wanted.

Because sanctioned races are held on closed courses there isn't much for sound regulations, therefore eliminating the need for silencers. In most cases you can take the very same mod sleds, put a quieter muffler on them and lose nothing but excess noise. Because they aren't required you just never see or hear them.

For years aftermarket companies produced and sold exhaust systems that were louder . not because that was what made the most power but because that's what the consumer wanted.  There wasn't much effort put into development of a quiet exhaust system because quiet wasn't selling. People wanted loud because it sounded cool and sounded fast. At the time nobody questioned it because a loud exhaust was the only aftermarket exhaust you could get. Today not only can a strong argument can be made that loud pipes are ruining our sport and restricting access to our land, but they that they don't produce the large horsepower gains once thought of.

A Gradual Shift

Gradually, we are beginning to see the aftermarket snowmobile exhaust market shift from loud to quiet. More and more we are seeing aftermarket companies advertising pipes that connect to the stock exhaust canisters of machines with little to no sound increase over a completely stock exhaust system. These pipes come with all the benefits of increased power and lighter weight, but by using the existing stock muffler, usually carry no increase in sound. Many aftermarket manufacturers are researching, developing, testing and selling quieter exhaust canisters than before. While many of these exhaust canisters still produce sound levels that are higher than the output of a completely stock machine, the market is constantly evolving and searching for ways to produce these products with noise levels that are equal to or less then stock.

Many states and provinces now have ordinances that prohibit loud exhaust noise. Snowmobile enthusiasts are beginning to take notice and are making conscious efforts to avoid exhausts that are loud. Aftermarket companies are following this trend and trying to produce exhausts that either meet these stricter standards or by discontinuing the sale of loud exhausts all together.

There are three pieces to the complete snowmobile exhaust: the head or Y pipe, the exhaust pipe and the canister. These three pieces all work together to scavenge the exhaust gasses and expel them in the most efficient manner possible. Modification to one of these components without regard to the others can produce less then desired results.

The first part of the exhaust that you see is the Y pipe. Also called the manifold, this is the piece that connects directly to the engine at the exhaust ports. Typically, consumers leave the Y pipe stock. You usually don't gain much by changing a Y pipe. While it is part of the overall system, it doesn't have any effect on the noise output.

The pipe is the middle part of the exhaust system and is the most important part. The pipe's primary purpose is to make power by scavenging the gasses created by combustion. Two stroke pipe design is a so called "black art." There are basic formulas that exist that will get you in the ballpark . pipe building is not an exact science. It is more than just choosing the appropriate angles and lengths of certain pieces.

A Pipe's Purpose

The entire pipe serves a purpose, including the head pipe diameter and length and the stinger diameter and length. The pipe also controls most of the back pressure.

Contrary to many enthusiasts, the pipe creates and controls most of the back pressure. The back pressure can be caused from a smaller diameter stinger or by a longer stinger section. Back pressure helps the wave action of the pipe by creating a more dense, uniform medium for the waves to act on. Waves travel better through consistent, dense mediums. However, this also causes the engine to run hotter, which isn't a good thing. The trick is to balance that amount and get the most useable power.

The exhaust canister (which may also be called silencers, canisters, cans or resonators) is most often to blame in the loud pipe debate.

The exhaust canister is the principle component used to muffle or reduce the sound of a snowmobile and is usually the first thing to be modified or replaced by those looking to enhance the sound of their sled. In the effort to comply with increasingly tougher standards for noise compliance, manufacturers sell new snowmobiles with exhaust systems that are very restricted in noise output and can weight in excess of 20 lbs.

The purpose of an aftermarket exhaust muffler is to shed weight from the snowmobile while possibly offering slight increases in horsepower, better throttle response, more under hood space and less under hood heat.

The trade off to these systems is noise and sometimes a drop in performance. While they may be smaller and lighter, they will also be louder.

Negative Effects

Many companies are starting to see the negative effects of loud canisters on the sport and are making concerted efforts to manufacture mufflers that are lighter than stock while still maintaining decibel levels close to stock. The weight and sound difference comes from the difference in overall size and the internal construction of the muffler.

Some aftermarket companies produce canisters that have a straight through design with virtually no restriction. These canisters are generally very light and are very loud in comparison to stock.

Other aftermarket manufacturers produce mufflers with internal packing, baffles or other sound reducing methods, which result in a slight weight increase over the straight through design, but much less overall noise. The weight and size of an exhaust canister generally correlates to the overall sound output. Typically, the bigger and heavier the exhaust is, the quieter it will be. This is because a bigger exhaust will most likely have more volume or area inside which can greatly reduce noise. The more volume the can has, the quieter it will be. Also, bigger exhausts have more room inside for internal packing, baffles or other sound reduction aids, which will increase the weight.

The exhaust canister also plays a small role in back pressure. Although the canister does not really create back pressure, it can help to control it when a pipe is designed with a silencer in mind. Today's machines are designed with specific parts which all serve a purpose. By changing out a silencer to something that is a more open design, you have completely changed how the system works and can alter any back pressure effect the pipe makes.

The manufacturing of snowmobile exhausts involves much more than forming and welding metal. While some companies may produce their product with little or no testing and development, reputable aftermarket companies spend countless hours in the design and testing of a new exhaust product.

To Each His Own

Each company may do things a little different, but most follow the same basic outline. At Black Magic Powersports, the process starts with any new model release. One of the first steps we take is to perform our own sound testing to establish a baseline. As with any testing, it is best to establish your own baseline. We use some of the same testing procedures that the Snowmobile Safety and Certification Committee (SSCC) uses to certify all new snowmobiles.

Using the (SAE) J192 test, any snowmobile produced after 1975 may emit no more then 78 decibels when tested from a distance of 50 feet while the snowmobile is traveling at full throttle.  Another test called the (SAE) J1161 test says that snowmobiles produced after June 30, 1976 must emit no more then 73 decibels when tested at a distance of 50 feet with the snowmobile traveling at a speed of 15 mph.

At Black Magic, we also use some other tests that aren't widely used yet but are being implemented in more areas. One of these tests, the J2567, requires the engine be brought to 4000 rpm and the sound meter measuring from a point exactly four meters from the point of the exhaust. Snowmobiles manufactured after July 1, 1975 must not emit more then 78 decibels when tested under the J2567 test. We will use all of these tests when establishing our stock baseline numbers and when testing any of our aftermarket exhausts.

After the stock baseline has been established, we can begin our testing on the other important things like acceleration, horsepower and torque, airflow, BSFC (brake specific fuel consumption) and more. Many of our procedures are similar to tests used by the OEMs.

We are not only doing various field tests on the exhaust but also spend countless hours in the dyno room and on a flowbench. After we have performed our actual field testing for the stock baselines on sound, acceleration and overall performance of the machine we will next go to the flowbench and then our Superflow dyno. Both the flowbench and dyno have become important tools used to develop exhausts, especially on the EFI machines from Arctic Cat.

Flowing Freely

The flowbench is our first stop to test and evaluate the airflow characteristics. We will first test the stock exhaust and get a baseline. We will use the stock baseline numbers as a guide when building prototypes, usually trying to keep numbers relatively close.

Generally speaking, if the airflow of a prototype is much less then the baseline number, that exhaust will be much tighter and won't work well. On the other hand, if the number is much higher, it will be too open and won't perform. The trick is to get the proto within a certain range. We can draw a pretty good conclusion on how the product will perform on the dyno and in the field before we even get there, all from flowbench testing.

Engine dynamometers have a very important role in the testing and development of any new performance product. Exhaust systems should be tested extensively on a dyno. While a dyno can never simulate real world conditions, it can give us vital information on performance characteristics and also aid us in tuning before we ever reach the final calibration phase of development.

Some things we are looking at for baseline numbers are the stock horsepower and torque, brake specific fuel consumption (BSFC) numbers, exhaust gas temperatures, water temps, oil temps and air/fuel ratios. We use these baseline numbers for comparison later on when testing the prototype exhaust to help tell us how the prototype will perform in the field.

When most people see a dyno sheet, the first thing they look at are corrected horsepower and torque. These numbers are important, but EGT numbers, BSFC, A/F ratios and water temperatures are just as vital as they will let the tuner know just what is happening when comparing a stock baseline number to a prototype and if changes such as jetting or fuel mapping are needed.

Design Change

Often when running dyno tests a problem can arise which may necessitate a design change.  When this happens we will start over with a new proto and repeat all our processes. When we find something that looks promising we then move on to field testing the product.

Perhaps the most important part of any product test is the field testing. During this part we test such things as sound, acceleration, top speed, fuel variables and durability.

Testing at Black Magic Powersports is an extensive project that often times consumes the entire winter and into spring. Some tests require the use of two machines, both of them performing as close to identical as possible. When we have both units running identical, we can then pick one for our baseline unit and use that to judge any gains or losses.

We install our exhaust on the non-baseline sled and run the sleds, comparing the bottom end and midrange acceleration and also the top speed. If we are satisfied with the results we can then move to other tests.

Partials, the testing of product at specific throttle position and speed, is a very important test we use. During this test, the snowmobile is run at different throttle positions, starting at idle and going in increments all the way to full throttle in an extended run of up to two miles or more. The sled is shut off and coasts to a stop where we will then do a plug check as well as a piston reading. This helps us determine the actual real world fuel settings and helps us find any lean conditions that may not be seen on the dyno.

Testing, Testing, Testing

While in the field we also conduct our own sound testing, comparing the numbers of our tests to the stock baseline numbers we have established. We may also stop and talk to random people along the way to get their opinion on the sound of the product. The final step of our field tests is our durability testing. During durability we are just putting miles on the product, some under heavy load and some under what we would consider normal consumer use. We use this testing to find any potential issues under the hood or breakage issues. We will also do some comparison runs after the product has been heat soaked and check for performance variables.

When we are satisfied that we have accomplished all of our goals-making an exhaust that is lightweight, produces the most available horsepower and torque, has a sound that is within reason, durable, fits great and looks nice-we can then begin to produce them for market.

Consumers must be conscious and aware of any possible affect resulting from their purchases.  Like it or not, loud snowmobiles are contributing to the loss of land. OEM manufacturers have been addressing this issue for years and aftermarket manufacturers are finally beginning to follow suit.

Ultimately it is up to the consumer to protect the sport. The consumer drives the market and controls the trend. When customers stop buying loud exhausts, they force the aftermarket companies to produce quieter products.

(Rantanen, along with his father, Arne, own Black Magic Powersports in Thief River Falls, MN. For more information, contact 218-681-1150 or

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