Yamaha has boosted horsepower nearly 10 percent on the Apex

Posted Oct. 29, 2010, at 10:27 a.m.

Yamaha engineers increased the performance of the new Apex by making a host of small updates that resulted in a new peak horsepower of 162.8 during independent Dynotech Research testing of a 2011 pre-production unit.

That’s a nearly 10-percent increase over the previous generation 4-cylinder Genesis engine. It boasts a ridiculously wide torque curve with a remarkable peak of 109.8 foot-pounds at 7,300 rpm for arm-stretching acceleration. Additionally, the Apex features the first Exhaust Ultimate Performance valve found in a snowmobile.

When it comes to raw torque, the Genesis Top Performance 4-stroke engine decimates the competition, according to independent Dynotech Research dyno testing. This engine makes 100 foot-pounds of torque for a range of 2,400 rpm, while the competitions’ 2-strokes make 100 foot-pounds of torque for an average range of only 500 rpm.

What all this mid-range torque advantage means to Yamaha Apex owners is amazing throttle response and acceleration off a back shift and coming out of the corner.

Yamaha engineers looked at every aspect of the Genesis 4-cylinder engine, from intake to exhaust, while working toward their new performance goal. New intake funnels in the air box are 11 millimeters longer than the previous engine. This increases air flow, which results in stronger low and mid-range performance in this latest generation engine.

Internally, new valve timing on the 2011 engine has 5 degrees more overlap than previous to flow more air, resulting in high rpm performance gains as well. To flow even more air efficiently, Yamaha’s engine-development team widened the exhaust pipe diameter. More high rpm air flow means more top-end power.

In the past, engine tuners were more or less confined to making either low or high rpm performance improvements, but achieving both was nearly impossible without facing a significant mid-range fall-off. However, Yamaha’s exclusive EXUP technology allows engineers to bridge the gap between the low rpm performance design changes and the high rpm design changes.

First introduced on the 1987 FZR400R sport bike, EXUP is a servo-controlled valve in the exhaust collector that modulates exhaust pressure waves to deliver optimum engine performance throughout the rpm range. Using exclusive technology to boost low-, mid-, and high-rpm engine performance with no sacrifice: That’s just one more Yamaha advantage that competitors can’t match.

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