Independent Dynotech Research testing confirms Genesis® Top Performance Engine output.

PLEASANT PRAIRIE, WI. –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 in independent Dynotech Research testing on a 2011 preproduction 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 ft/lbs at 7300 rpm for arm-stretching acceleration. Additionally, it features the first Exhaust Ultimate Performance, or EXUP® valve found in a snowmobile.

When it comes to straightforward raw torque, the Genesis Top Performance 4-stroke engine decimates the competition, according to independent Dynotech Research dyno testing. It shows a staggering 32% midrange torque advantage over the 2011 Polaris® 800 Rush® preproduction unit and 25% more midrange torque than the early release 2011 Ski-Doo® 800 E-Tec®. Even Arctic Cat®’s production F8™ falls 17 percent short to the newest 4-cylinder Genesis 4-stroke engine in midrange torque! This 4-cylinder engine makes 100+ ft/lbs of torque for a range of 2400 rpm while the competition’s 2-strokes make 100+ ft/lbs of torque for an average range of only 500 rpm. What all this midrange torque advantage means to Yamaha Apex owners is amazing throttle response and acceleration off of a backshift and coming out of the corner.

Many small changes make a big difference
Yamaha engine 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 airbox are 11mm longer than the previous engine, increasing airflow which results in stronger low and midrange 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. In order to flow even more air efficiently, Yamaha’s engine development team widened the exhaust pipe diameter, going from 35 mm to 38.1 mm and have changed to a 4-1 design. More high rpm airflow means more top-end power.

Using technology to Yamaha’s Advantage
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 midrange fall-off. However, Yamaha’s exclusive EXUP technology allows engineers to bridge the gap between the new 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. At low rpm the valve is in the closed position to modulate the exhaust pressure wave to reduce power loss due to the “blowback” phenomenon created by the increased engine valve overlap. The EXUP valve opens incrementally as engine speed increases, further modulating the sound wave until it is wide open at high rpm. When the EXUP valve is open, the engine is flowing maximum air, producing that high rpm, peak horsepower gain. Using exclusive technology to boost low, mid and high rpm engine performance with no sacrifice: that’s just one more Yamaha advantage competitors can’t match.

The new 2011 Genesis Top Performance 4-cylinder engine delivers in ways two stroke competitors simply can’t. Its impressive 162.8 HP, broad torque band, and EXUP exhaust technology put 4-stroke performance at a new high. Add the Yamaha Advantage of #1 Reliability and you have a sled the 2-strokes can’t touch!