How to Increase Horsepower on a Mercury Outboard Motor

by Erick KristianUpdated November 07, 2017
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Mercury outboard motors are very popular among boating enthusiasts. Mercury offers a full line of motors with varying degrees of power output. Mercury engines are already quite efficient and it can be difficult to increase the power significantly; however, there are a number of ways to pull out incremental power from the motor. The amount of power that can be increased is directly proportional to the size of the engine. For example, obtaining two extra horsepower, or hp, from a 120 hp engine may not be difficult, but would be impossible from a 5 hp engine.

Perform a full service tune on the engine. This will help the engine last longer and increase its efficiency. Change the fuel, check the oil and other levels. Clean the engine and perform a thorough maintenance on the engine. This will ensure the engine is in the best condition possible. A seldom serviced engine will not perform as well as a frequently serviced one.

Use fuel additives. Fuel additives are chemical mixtures designed to help increase performance and efficiency. There are many additives to chose from; some are designed for small engines others for larger ones. The right additive is the one designed for your engine. They are generally inexpensive (less than $20) and last a long time. Often only a small amount is added to a full fuel tank.

Increase performance through airflow intake. The engine sucks in air and blows air out. If this process is hindered, then performance is lost. Examine the air intake on the engine. Look for obstructions, debris or other dirt that may clog the engine. Clean the air intake thoroughly. Examine the air filter and replace if it is dirty or damaged.

Increase performance through airflow exhaust. If the exhaust (air leaving the engine) is restricted, it can cause pressure to build up and reduce the efficiency of the engine and its power. Replacing the exhaust unit with an after-market system can help increase performance.

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