A snowmobile-style tunnel cooler heat exchanger can be a great addition to your cooling system for those spring riding days or for your turbocharged or big bore engines.

This custom hose kit – click here is recommended to plumb it all up!

PLEASE READ THE BELOW BEFORE PURCHASING:
DO I NEED A TUNNEL COOLER?
On a stock 450, honestly, no you don’t.
On a hopped-up big-bore, or a turbo bike? Yes!
Somewhere in between? Up to you.
The scenario where the cooler does become super valuable is sustained high-rev low-speed pulls, which is certainly not uncommon when hillclimbing in spring conditions.
Please also consider the next paragraph to see if there’s other factors you should be checking first:
REALLY? I DON’T NEED A TUNNEL COOLER FOR MY 450? BUT IT OVERHEATS OFTEN?
If your 450 is overheating in winter conditions, there is something else going on…

Which thermostat are you using? C3’s properly sized small-diameter bypass setup is both A) more effective at building heat in a cold scenario and B) doesn’t circulate excessive amounts of hot coolant in a hot scenario, so if you are not satisfied with your engine temps, we suggest you switch to a C3 Powersports Thermostat if you don’t already have one.
What rad guards are you using? Some rad guards can get jammed full of snow, which blocks airflow to the radiators and inhibits cooling.
What engine enclosure are you using? Engine enclosures obviously influence heat building significantly, and many styles increase potential for overheating in certain conditions. One often-overlooked details has to do with airflow out the back of the rads. If the backs of the rads are closed in, the airflow through the system is highly reduced. Highly insulated jackets or enclosures with a heater built in can also swing the temp equilibrium too far the other way towards overheating.
Yes, a tunnel cooler can be a fix to the above, but addressing those root causes may be the better/easier way to accomplish your goal.

WHAT SIZE COOLER DO I NEED?
In 95% of cases, we recommend the 12″/single. Bigger does not necessarily equal better.
The builds that necessitate the 30″/double are mainly A) big-bore 2-strokes like BRC 500 or B) turbocharged or supercharged engines.
If in doubt, go for the smaller option.
HOW DOES IT WORK?
We suggest to plumb the main coolant line directly downstream of the thermostat to the cooler, then return through the rads. Each kit on this page includes some hardware that will help you mount the unit.

The YETI option picks up the rear CargoRak / Plan B Can mounts to hold the rear of the cooler, and one bolt through the front of the cooler. It does require you to drill two holes in your chassis for the cooler to pass through.
For YETI, the 30″ length will fit on the 2017 and newer models only.
The Timbersled cooler works by removing the non-drive (rider’s right hand) side plate, then reinstalling with the cooler in the space between the center frame and the side plate.
For Timbersled, the 30″ length will fit on Gen 1 ARO only (not Riot and not Gen 2 ARO (2023+ ARO 3))
Also, neither size will fit the Mountain Horse platform (mainly 2017 or earlier)
The MTN.TOP cooler requires one hole to be drilled in the side plate, but just drops in to the tubular frame structure.
In every case, be advised that this is not 100% “plug and play.” Ultimately, this product is only recommended for experienced users who are comfortable making modifications, resourceful, and prepared to do some custom wrenching. If you are not 100% confident in your abilities, consider hiring a dealership or snowbike builder in your area.