BY DAVID WELLS

Free air snowmobile engine cooling was very popular during the vintage era because it offered a lot of advantages . It was light weight and less expensive than any other cooling type due to fewer parts . It was also highly efficient in cold weather , easy to maintain and rebuild , and relatively quiet compared to the often obnoxious whine of an over-driven axial cooling fan .

All of that and more made free air cooling a big hit . It was widely and successfully used by more than two dozen brands , particularly on race sleds and sporty trail performance models .

But as the years rolled on , free air cooling began to fall out of favor . Fully-enclosed hoods for noise suppression were not an option for free air engines , which had to be located in a location with high-volume air flow to cool the engine properly .

In addition , free air cooling was nowhere near as good at maintaining consistent engine temperatures as other cooling methods , depressing power output by as much as 30 percent as the engine got hot . And it just wasn ’ t as effective as other cooling methods in warm weather , either .

So liquid cooling began to replace free air as the cooling choice for performance sleds . A final and very crucial factor was when Rotax produced unreliable free air engines for Bombardier sleds , and that gave free air engines a bad rap that was simply not deserved by any of the other many brands that used it successfully .

However , the lower weight and cost of free air engines allowed them to stick around on economical and sporty trail sleds all the way to the beginning of the 1980s .

Deere Does It Two Ways

When John Deere introduced its new Sprintfire and Snowfire as mid-season 1982 models , they were essentially slightly enlarged and improved Spitfires capable of carrying two riders .

The more upscale Sprintfire had a liquid-cooled 340 with oil injection , while the price-leader Snowfire had a free air 340 that ran on pre-mix to keep cost down . This engine was actually the same one used in the revolutionary Spitfire , but with a Y-pipe exhaust header that was more efficient than the F-pipe header on the Spitfire . Therefore , the Snowfire engine made a little more horsepower .

The free air engine was combined with a nearly all-aluminum chassis to allow Deere to promote the 314-pound Snowfire as the lightest 340cc snowmobile on the market . This made the Snowfire easier to influence with body positioning while also being simpler to dig out when it was stuck and easier to trailer than competitive models . Deere also promoted less maintenance , pointing out that there were no fan belts to break on the light weight Snowfire .

At a good 20 pounds lighter and $ 500 less expensive at retail than the Sprintfire , the Snowfire also lacked its more expensive sibling ’ s standard equipment speedometer and warning lights . But both machines were positioned as trail sleds for family fun , including being particularly appealing for first-time buyers or smaller riders .

Factory fuel mileage estimates , developed on Deere ’ s dynamometers instead of out on the trail , illustrate one of the operational differences between these engines . The Sprintfire ’ s liquid-cooled engine was rated at 28 miles per gallon ( MPG ), while the Snowfire ’ s free air was rated at 22 MPG .

Realistically , both of these engines could do better under ideal conditions , and a 1984 Snowfire recorded 23.63 MPG in the second annual Snow Goer fuel economy tests , the best of any air-cooled twin under 400cc that was tested from any brand . But the Snowfire could also do much worse under adverse conditions like deep snow or mealy wet snow in above-freezing temperatures .

The Snow Goer team at the time had previously tested an essentially identical 1983 Snowfire and had some interesting comments .

“ In test riding , we ’ ve found Deere ’ s long-travel suspension to be effective in absorbing some of the bigger bumps on the trail ,” editors wrote . “ On moguled sections , especially , it produced a smooth ride . The system is not as progressive as we expected it to be , however .”

Cornering was not viewed as favorably , though , due to less weight on the skis and the long-travel ( for the time ) rear suspension . The Snowfire was also inferior to other Deere models in deep snow . Nevertheless , the Snowfire got a positive overall review . “ Surprisingly peppy at low end and mid-range ,” our testers reported . “ It ’ s a family machine with the emphasis on the wife and kids . Ideal as a second snowmobile .” Others liked it , too . “ The Snowfire is fun to ride ,” concluded Snowmobile mag-

10 / FEBRUARY 2025 / SNOWGOER . COM