Mercury Racing outboard fitted with a special Sport Master or Torque Master gear case, or a modified lower unit with a Bobs nose cone kit. How about an SLE, SST lower Unit, IMCO, Yamaha VZ, Yamaha OO, or Alpha 1 SS gearcase or Superspeed Master.
Yes all of the above have the potential to increase your top end MPH. Especially since they also have a torpedoed style nose cone, crescent leading edge and slender strut and skeg to reduce the coefficient of drag.
In order to get the most out of your low water pick up gearcase, and pick up lots of top end speed. It's all going to come down to set up! Including Propeller, motor height and setback.
1) Go Straight
I heard from the big time tuners to use less positive trim. When the lower units are pointed straight, the thrust from the propellers goes straight aft. When the outboards or lower units are trimmed out/up, the noses point down and the thrust is directed up, not aft. This increases fuel consumption and reduces efficiency.
2) Prop it right
Ask around see what size props your fellow racers are using that seem to work best. Try different props until the performance you desire is met.
3) Tall Tail
Regardless of the class of boat, during a race you can tell which team is running at its most efficient because the roostertail lowers as the boat accelerates. When a high-speed catamaran or stepped V-bottom runs at high speed, it has virtually no roostertail at all. So if your boat’s roostertail gets smaller as you make improvements, you are probably doing things right.
5. Jacking it up
To get the most out of your Outboard's mount them on a jack plate. Engine position is critical when traveling at high speeds. The higher your motor is mounted raising the lower unit out of the water the less drag. Of course another good reason you need low water intakes to keep the water pressure for cooling at proper pressures.
Jack plates can also be used to adjust the setback, or how far back the motors are from the transom. Setback helps ensure the prop is not in aerated water.
On the maintenance side, make sure you run the correct octane fuel and use a quality two-stroke oil. Change the lower unit’s oil frequently, and when you do, inspect the drain plug, which is magnetic, for metal shavings that could indicate wear. It is also recommended to change lower-unit impellers and propeller nuts annually.
Pull the cowlings and inspect your outboards’ powerheads to make sure nothing looks out of the ordinary. Keep the propeller shaft greased and, if you boat in salt water, take the cowling off and wipe down the motor with CRC or another lubricant.
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