2019 4 Stroke Turbo Comparison Yamaha VS Ski Doo

There's this strange assumption in the minds of many motorheads that adding a turbo to anything makes it better. And I have to admit, I kind of agree. More power equals more gooder. This season is a big one for turbo fanatics too. Until now, if you wanted a legit four-stroke turbo, you only had three choices. The Yamaha Sidewinder, Articat 9000, or build your own. Skidoo's 2019 release of the Ace 900 Turbo has given spoolheads another option. It's also created a whole new debate. Which turbo is best? Yamaha's 998 or Skidoo's 900? Yes, I do get that these two motors don't compete head-to-head. One is 150 horsepower, one is 180 plus horsepower. They're not equals. But you asked the question, and today I intend to not necessarily answer it, but instead provide some insight into what we like and possibly dislike about each. The veteran here is Yamaha's Genesis 998cc triple. It has four valves per cylinder and features a pressed forged crank and cast steel exhaust manifold. The turbo itself has a nickel alloy turbine body and is liquid cooled to help keep underhood temps in check. Yamaha's fuel injection system feeds a triple throttle body layout. And it's this system that's responsible for the almost two-stroke-like throttle response of this motor. There's also an intercooler, of course. The new kid on the block, so to speak, is Skidoo's Ace 900 Turbo. It's based on the naturally aspirated Ace 900, but the reality is these two motors are more different than they are the same. The Ace displaces 899cc's exactly. It has dual overhead cams and breathes through a single throttle body that feeds three injectors. The internals of the Ace 900 Turbo have been beefed up with cast pistons, reinforced connecting rods, reinforced crankshaft, and a wider connecting rod bearing. A larger water pump bumps up the cooling through a revised cylinder head and a new oil pump increases oil flow. A Rotax designed and built small diameter, fast spooling, liquid cooled turbo with a nickel alloy turbine sits directly on top of the three into one exhaust manifold. Now let's take some time to compare these two motors and I want to start with how they are mounted in their chassis. A snowmobile isn't just a motor and it's not just the chassis, it's a combination of both. So how they relate to each other is extremely important. Yamaha's 998 Triple isn't the lightest of these two motors. It also wasn't specifically built to fit in the SRV chassis. The chassis was more built for the engine, but even still the layout of the motor prevents it from being mounted as low as possible in the chassis. This leaves the single heaviest component of the sled sitting higher than it optimally should be, which results in higher overall center of gravity. Skidoo's Ace 900 is definitely the lighter of these two engines and it was specifically designed and built to fit as low as possible in the Gen 4 chassis. The result is a sled that corners flatter and feels more nimble when things get tight and twisty. Obviously this doesn't have anything to do with power. Or does it? Actually it does. Because the Ace motor is mounted so low in the Gen 4 chassis there simply isn't room for a triple throttle body setup like the Yamaha has. It also requires the single throttle body to be positioned a longer than optimal distance from the intake ports. The result of this setup is a small amount of throttle lag. Some might confuse this feeling with turbo lag, but it isn't and we'll talk more about that in a bit. Skidoo has attempted to minimize this effect by using their drive-by-wire throttle to ramp up the throttle-to-butterfly ratio inside the throttle body, but it's only minimally effective. On the flip side, the Yamaha's higher engine mounting position leaves more room for triple throttle bodies to be located very close to the intake ports on the engine. And since there's three of them there is absolutely no throttle lag. The Yamaha triple's throttle response is as close to a two-stroke as any four-stroke we've ever ridden. On the opposite side of the motor we find an almost opposite situation. Yamaha's turbo is more traditionally located farther away from the exhaust ports a small distance down from the exhaust manifold. This means it takes a small amount of time for the exhaust gases to reach the turbo and for the turbo to begin creating boost. This is what's known as turbo lag. BRP has located the Ace 900's turbo directly on top of the exhaust manifold, which means there's pretty much no time between when the exhaust gases leave the exhaust port to when they reach the turbo, which means there is no turbo lag. You may be wondering which of these two scenarios is the best compromise in a snowmobile application. And in our opinion, having snappy throttle response and a tiny bit of turbo lag is better than a bit of throttle lag but instant boost. Your opinion may vary. The reality is, aside from horsepower, this is what sets these two motors apart the most. Now if you're going for ultimate top speed, weight and center of gravity probably aren't a huge concern for you, so you're going to take the high horsepower of the Yamaha. If you want a more agile sled on the trail, the lightweight and low center of gravity of the Skidoo makes it the better choice. The Skidoo is still crazy fast and it gets up to speed with arm-stretching urgency, but it can't match the outright aggression the Yamaha seems to have when the throttle is pulled all the way open. At the end of the day, they aren't comparable in any other way than how the air gets to the intake, but wondering how they differ in terms of on-trail feel is understandable. Neither is better or worse, they're just different and they're both great in their own way. If you enjoyed that video, make sure you hit the like button and then subscribe to SnowtraxTV's YouTube channel that's constantly being updated with fresh content.