1999 phazer v 1999 super sport

Phazer versus Super Sport. It's a matchup we knew would be key this season.Despite manufacturer protestations, these two sleds are ostensibly aimeddirectly at each other. Consumers don't care that one sled is a 550 andthe other is a 500. In the minds of the masses, and us, too, these sledsare direct competitors. So it made perfect sense to have our own mini dynoshoot-out.

The renovated Phazer was really a no-brainer for us. While that sledenjoyed tremendous sales in the mid-eighties, it had tailed off significantlyas other makes stepped up the technology race. Despite the emergence offaster, more nimble machines, though, the Phazer maintained somewhat ofa cult following. Those who liked the snow cyclops were faithful. But eventhe VW Bug gets a facelift eventually. So, too, the Phazer.

However, the new Yamaha fan-cooled machine is more than a cosmetic job.There's a new motor under the new hood. Yamaha recast the mold for its fan-cooledmill, creating a lighter, stronger and more durable product. The bore andstroke dimensions remain the same as previous years, 72mm by 59.6mm.

The increase in power comes from rescheduled port timing and a host ofother alterations to the Phazer mill, from intake to exhaust. Yamaha incorporatesa new larger airbox to help the fan-cooled engine breathe a bit easier.Also included is the Yamaha Energy Induction System (YEIS) boost bottleto the intake. It is said to improve low and mid range power output andincrease fuel economy by balancing the air charge going into the cylinders.The Phazer engine keeps the proven reed valve induction system.

The Phazer also uses a pair of improved Mikuni 38-32mm butterfly carbs.They give a super light throttle pull, and, since you're not lifting a slide,the throttle movement is very short. A good thing for those with small hands.

To improve durability, Yamaha engineers increased the crank shaft bearingsize from 68mm to 78mm (15 percent increase) on all five bearings in orderto better handle the increased power. The spline joint on the crank is offsetfor the same reason.

Yamaha engineers relocated the oil pump to the bottom center of the caseto help lower the center of gravity.

At the tail end of the powerplant, the Phazer uses a new lightweight,high volume pipe and muffler.

So how does it all work? Pretty well. We'll delve into the test analysisin a bit.

The Polaris Super Sport was a bit of a surprise. We weren't expectingto see a new 550 fan-cooled sled come out of Roseau. Polaris claims, rightfully,that it is the largest and most powerful fan-cooled snowmobile engine inproduction. But we'll get to that later.

The mill measures 73mm by 65mm, a one millimeter increase in bore anda five millimeter larger stroke. Doing the math, we find that this increasedthe total displacement by 56cc to 544cc.

Fuji and Polaris tag teamed on the new motor, which uses a new reed valveassist induction design. In a nutshell, the reed valve gives the enginemore intake duration without having a gaping hole for an intake port. Ifthe motor were to have the same intake duration without the reeds, someof the fresh fuel/air mixture could enter the cylinder, swirl around andexit back through the intake port, losing some of the charge. This wouldresult in a loss of power, especially on the low- and midrange. What thereed assist does, is allow most of the fuel charge to enter the cylinderthrough the intake port. As the piston approaches BDC (Bottom Dead Center),it closes the intake port, but leaves the reed valve open slightly longer,allowing the cylinder to fill up even more. How does this happen? The columnof fuel/air mixture has some momentum as it is being sucked into the cylinderfrom the carb. When the intake port is suddenly closed, the reed valve allowsit to continue moving into the cylinder, to be burned and make power. It'sa trick concept that seems to work well.

Polaris tells us that the new design not only boosts the horsepower overthe old 488 motor, but it also delivers better fuel economy. The companyclaims an 18 percent gain at 25 miles per hour and a 10 percent gain at45 mph. Also adding to the fuel economy equation is a pair of 34mm roundslide Mikuni carbs.

For added durability, the new 550 motor uses double row bearings at themag side, and a beefed up crankshaft.

Our dynoman, Rich Daly, didn't take long to find the power on the twofan-cooled machines. "We got a very wide powerband on the Phazer,"he told us. "From about 6800 rpm up through 7200, we are over 61 horses.That's not going to be hard for a guy to hit with his clutching.

"The same is true for the Super Sport. Polaris' motor is a bit stronger,but just a little narrower on the power band," Daly continued. "From6800 through 7000 rpm, it is pulling over 65 horsepower."

Both sleds also have the torque curve hit early, then tail off graduallyas the horsepower increases. That's pretty much what we had expected tosee on these sleds. The Phazer produced 48.3 foot pounds of torque at 6300while the Super Sport generated 52.9 foot pounds at 6100 rpm.

One other aspect of fan-cooled sleds that showed up on our dyno testsis the increased brake specific fuel consumption (BSFC). This is a measureof the engine's fuel efficiency and is quantified in pounds of fuel perhorsepower produced. It is to be expected that a fan-cooled engine willregister higher BSFC figures than a liquid-cooled engine because of theincreased dependency on the fresh fuel/air charge as a cooling agent. Byway of comparison, the 500 XC motor we dynoed in the October '98 issue hadBSFCs in the upper .5 to lower .6 range. Both of our fan-cooled test subjectsthis month ran BSFCs in the .7 to .8 range.

"I tried to lean out the jetting on both motors," said Daly."But they lost power when I did it. These engines need to run in the.73 range or they're just not happy."

We'll be receiving both of these sleds for our long-term torture testthis winter. Look for a full performance and economy report in next year'sissues!