A pair of Mercury Racing 450R outboard push the MTI 340X to a top speed of 128 mph. Courtesy Mercury Racing

Mercury Racing and MTI have been able to push the powerboat industry at top speeds. This includes the MTI 340X which reached top speeds of 128 mph running a pair of Mercury Racing 450R outboard engines. Read the article below to find out more about the high performance boats and their intense performance.

At the media intro for the new Mercury Racing 450R outboard, we had a chance to catch a ride in the same 34-foot MTI 340X catamaran Mercury used to introduce its Mercury Racing 300R outboard last spring. The boat belongs to Mercury Racing and has been used as a test bed for its series of new high-performance motors. At the events we attend, the boat is manned by MTI staff, and at the Nashville intro for the 450R Mike Griffiths of MTI was managing the throttles. We asked Griffiths to compare the 450R to the 400R.

“The 400R starts out strong but then seems to sort of run out of breath as you build up speed,” said Griffiths. “The 450R torque starts early and stays linear. This motor pulls hard all the way to wide-open throttle.”

What about top speed?

Griffith said recent testing was conducted to make a valid comparison between the 300R, a 4.6-liter naturally aspirated V8, the 2.6-liter supercharged Verado 400R L6, and the 4.6-liter supercharged V8 450R.

Powered by a pair of Mercury Racing 300R outboards (with the new 1.6:1 gear ratio Sport Master gearcase and 15 x 33 inch five-blade Mercury Racing Outboard CNC Cleaver props) the 340X topped out at 115 mph.

The Mercury Racing 450R outboards rigged on the MTI 340X feature a new integrated tie bar bracket.Courtesy Mercury Racing

A pair of 400R outboards with 1.75:1 ratio Sport Master and 15 x 34 inch five-blade Outboard CNC Cleaver props pushed the same boat to a top speed of 121 mph, according to Griffiths. At the Lake X intro for the 300R, MTI Marketing Manager Tom Stuart told us that the torque curves for the 300R and 400R are very similar. That, coupled with the optimized timing advance provided by Transient Spark Technology feature of the 300R and its 156-pound weight advantage over the 400R, helps the 300R-powered boat out-accelerate the 400R. But because it has more peak power and a rev limit that’s 600 rpm higher than the 300R, the 400R will beat the new motor in top speed.

How about the new 450R? With a similar light load of passengers and fuel the MTI 340X reached 128 mph with a pair of 450R motors on the transom, turning 15 x 35 inch five-blade Outboard CNC Cleaver props through a 1.60:1 gear ratio. That’s fast. But fast is always expensive; pricing for the 450R ranges from $54,000 to $64,000 depending on gearcase and other options – about 50 percent more than the Mercury Racing 400R. So how fast can you afford to go?

Original article published on