Over the last decade, three 4-stroke configurations have dominated: The Apex’s inline 4, Yamaha and Rotax’s triples and the twins used in the Phazer, ACE 600, Polaris’s 750cc Weber and the 1056cc Suzuki twin used in Arctic Cat’s 9000 Turbo and 5000-series.
Without question, the largest selling engine configuration for 4-stroke snowmobiles is the triple. Ski-Doo’s ACE 900 and 1170 triples account for a very large percentage of 4-stroke sales and so does Yamaha’s 1049 used in the Viper and 7000-series Cats. What is it about an inline-3 that makes it so appealing?
Certainly, a triple requires more parts and complexity than a twin – and more potential for friction and weight. Some triples tend to make their power at a slightly higher RPM level than twins do – especially even-firing twins. This isn’t always a bad thing because a 3-cylinder engine’s 120-degree firing order tends to make the engine turbine-smooth in the upper ranges and CVT clutching makes up for the rest.
There’s also that incredibly soothing exhaust tone you get with a triple. Somehow, at full cry, it just sounds right. Even the inline-4 in the Apex, firing every 90-degrees has a distinctive and very pleasant sound compared to a twin.
Those multi-cylinder configurations don’t usually need counterbalancing either and that helps offset the extra weight more valve train complexity may bring.
One thing we’ve observed about 2-cylinder engines, however, is their amazing durability. The Suzuki 1056 makes 123-hp in its naturally aspirated (EFI) form and that same engine can be boosted beyond the 177-hp the stock Cat Turbo makes, to a safe, reliable 270-hp. Incredible!
Even-firing twins like the above-mentioned Suzuki and the former Polaris Weber do not possess the sweet exhaust tone of the triples or the Apex 4, even though their power output is impressive. It’s a bit of a marketing negative and it can be fixed by making a twin alternate firing like the Phazer’s 500 (180-degrees). That particular engine’s exhaust is a sweet sounding symphony and easily matches a triple’s sound for pure adrenaline generation.
Just a note: Polaris’ off-road series of 900 and 1000cc ProStar 4-stroke twins are alternate-firing and these engines sound super-sweet, too. Just sayin’.