April 10, 2020

Can a Snowmobile Run Without An Airbox?

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Is there anything better than fresh powder? The roar of your snowmobile engine is dampened by the pristine white hanging to the tree boughs. You easily cut through the smooth white canvas blazing your own original trail throwing a tail of snow behind you. You’ve heard there’s an easy way to modify your snowmobile to get more power. But is it true?

Can a snowmobile run without an airbox? It can but removing or modifying your airbox will make your snowmobile sound like it has more power, but by drilling new holes or tapping existing holes in your airbox, running without the box lid, or removing it altogether will result in poorer performance.

Sure, there are many do it yourself YouTube videos and articles about how to remove or modify your snowmobile’s airbox, but is it something you really want to do? 

What Does The Airbox Do For A Snowmobile?

The airbox is a device that is responsible for managing the air pressure differential between your sled’s internal pressure and the local atmospheric pressure. This process allows you to have consistent fuel delivery regardless of altitude or temperature. 

Your overall velocity is also influenced by the airbox’s performance. Said differently, if you remove or open up your airbox, you have less internal pressure—the lower the internal pressure, the lower your speed. 

Enlarging the opening of the intake does not enhance your sled’s performance. Instead, you end up with lagging throttle response.

Here’s the why behind if you remove the airbox, you have actually negatively impacted your sled’s speed. By opening the carburetor up to unrestricted airflow, you are lowering the internal pressure. 

When this happens, sure you have plenty of air getting to the intake, but it chokes the overall air velocity. By allowing too much air, you end up hindering fuel delivery due to the lack of variance between internal pressure and the external atmospheric pressure.

Meltdowns Versus Keeping Cool Under Pressure

If you want your snowmobile to act like a toddler who was just told no, by all means. Eliminate your sled’s airbox.

One thing the airbox does for your snowmobile is to make sure that your engine is getting clean, cold external air instead of only recirculating the hot air pushed out by the engine.

Think of it this way: the denser the air, the better the combustion in the chamber to enhance horsepower and performance. Cooler air has a greater density level than hot air. 

What’s easier for you to breathe? Cool air or hot air? Cool air is refreshing and invigorating. It provides you with more energy to get things done. Hot air, on the other hand, depletes your energy. The same is true for your sled.

Some may suggest that you simply run your RPMs at a critical range to solve this issue. Would you regularly redline your car? Of course not. Ramping things up like this will likely burn up your bearings, clutch, and pistons. Feel that new vibration as you ramp up your RPMs? You’re well on your way to serious engine trouble.

Snowpack Where It Doesn’t Belong

Another reason to avoid opening up your snowmobile airbox with more holes, removing the lid, or removing it altogether is that you end up with snow in places it doesn’t belong.

Making sure your engine is getting the right mix of external cold air and recycled hot air is one thing. Ending up with a block full of snow is nothing short of frustrating – even flat out irritating. This is one thing that often happens when you open up your airbox.

Most airboxes are surrounded by a pre-filter material that normally blocks the snow from getting in there. Cutting holes through that or removing it altogether does nothing to protect that area from snow build-up.

Riding on Snowmobile2

This snow packing around your intake system does nothing but cause your engine to seize up and potentially burn down – even with the carburetor jetted on the rich side. Considering that your goal was to increase your sled’s speed and performance, you just ended up with a counterproductive result.

New Versus “Vintage” Models Concerning the Airbox

As you visit various forums and watch videos, you may hear that the newer models don’t have airboxes – that this is strictly a vintage (1970’s, 80’s, 90’s) snowmobile issue. That is not true.

The brand new 2020 and upcoming 2021 models have airboxes too.

The big difference is that, just like most technology, there have been significant improvements in the parts developments over the years. That doesn’t mean that people aren’t still trying to sell you on getting better performance by modifying the airbox.

Air Filters Instead of the Airbox

There are several recommendations suggesting that using various air filters in place of the airbox will care for the poor performance issue. Unfortunately, this is also inaccurate.

The obvious concern is that using air filters in place of the airbox doesn’t care for the snowpack around the block issue.

Less obvious is that many of the filters that are recommended in various forums are those that are designed for ATVs, dirt bikes, or other less-powerful machines. When this solution is used, in combination with a power jet carburetor, it often results in shaking because the engine is seizing.

Other Potential Modifications for Your Snowmobile

If you really want to modify your airbox, a possible solution could be to install a Total Performance Intake (TPI) valve at the top of your airbox. It has a built-in filter to help resolve some of the issues already discussed.

If you want to get better performance then check out these performance mods at Sled360 that will increase your performance.

Installing a TPI Valve

Installation is as easy as two, simple steps:

  • Cut a two-inch diameter hole in the top of your airbox
  • Insert the TPI in the opening

This new valve has a sliding door that allows you to control the amount of airspeed and pressure that is flowing into the airbox.

You will need to experiment with various positions to figure out how open the TPI door must be as it relates to where your sled has its best performance. Should you open the door ¼ of the way? Halfway? All the way? 

Only you can make the decision as to how much jetting you need based on the environment, you’re in that day. Are you at a higher altitude with thinner air? Are you in near-zero temperatures, or is it a 40+ degree spring day? These will factor into your snowmobile’s performance.

Dial-a-Jet

If you’re still looking for better throttle response, another product you may want to explore is the Dial-a-Jet fuel induction system. It is known for improving fuel efficiency. It is reputed to work well with many engine types and exhaust systems, whether stock or modified, as well as standard and high-performance airboxes.

Cutting Your Snowmobile Through The Snow

It doesn’t matter if you have a brand-new snowmobile model or one you inherited from the 1980s. Whenever there’s an engine involved, wanting to go harder and faster is inevitable. If you’re getting into professional racing, even at an entry-level, it’s time to invest in a racing sled. 

extreme action snowmobile

Otherwise, it may be time to focus on the glorious environment around you while you’re out and about throwing rooster tails behind you.

If bouncing over the terrain while you’re playing tag with your snowmobiling sidekick isn’t thrilling enough for you, maybe you should pick up a rider and figure out where those adventures are going to take you.

Regardless, get out there, have fun, and blaze your own trails.

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Helmet Fox Racing V3 Helmet (Check Why It Is My Favorite at DirtWheelRider)

Gloves Carhartt WP Gloves

Boots Fly Racing Marker Boots

Jacket Fly Racing Aurora Snowmobile Jacket

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Article written by Matt Powell
Hi, I am Matt and I have been playing outdoor games as long as I can remember. Today I have several games that I play on the regular and got together with Josh here on Outdoor Diversions so we could share our passion for the outdoors, gaming, and sports with you.