Randy Corson, owner of Liberator Boats of Florida has documented the performance of the first 21 Liberator rigged with the new 4.6-liter four-stroke V8 Mercury Racing 300R outboard. Corson has typically rigged this tunnel hull runaboat with a Mercury Racing 300XS V6 two-stroke outboard.
The Mercury Racing 300R offers 44 percent more displacement than the legacy 300XS and produces 40 percent more bottom-end torque and provides 25 percent quicker acceleration, according to Mercury Racing.
“The V-8 four-stroke produces so much torque that it demands a larger diameter prop,” said Corson. “We saw 1.5 to 2 mph faster top-end speeds with the 300R compared to the 300XS with comparable props. The boat topped out at 106 mph, or 5 to 6 mph faster than the 300XS when running a 15.25 x 34-inch pitch Mercury Racing 5-blade CNC outboard cleaver.”
The 21 Liberator also ran well with a combination of the 300R outboard and the MAX5, a Mercury Racing sterndrive prop that is finding success in select outboard cat and vee applications. Corson reports prop slip of just 9.7 percent and a top-end speed of 103 mph at 6200 rpm.
“The engine has an awesome sound from outside of boat, yet is uncommonly quiet inside,” said Corson. “It’s really the best of both worlds for the modern-day outboard performance boater.”
See video of the 21 Liberator running here: 21 Liberator 300R.