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Gas Boat Tuned Pipe

Gas Boat Tuned Pipe – Introduction

It is important to understand the basic function of a tuned pipe and how to get it to do what it is used for. A tuned pipe is best known for its performance boost in 2 stroke internal combustion engines. For radio control boat applications it serves a purpose to provide power on the higher RPM range. This will result in an overall higher top speed.

Design of a Gas Boat Tuned Pipe

Tuned pipes are often known to take the shape of placing two cones end on end. This idea plays a large role in how a tuned pipe functions.
When exhaust gases exit the engine and head in to the tuned pipe, the pressure wave first crosses over the cone that slowly grows in diameter. Once it reaches the end the pressure wave hits the cone that slowly decreases in diameter. During this transition the pressure wave from the exhaust hits the second cone and is deflected back towards the engine. This deflection increases a two stroke engines efficiency. The pressure deflection pushes the intake charge that ends up in the exhaust header back in to the engine. The extra fuel in the engine produces more power.

Installing a Gas Boat Tuned Pipe

A tuned pipe is not a direct bolt on. It must be installed correctly. An incorrect installation will not have the timing for the tuned pipe set in the correct spot, not providing peak power.

To set the tuned pipe correctly the length of the pipe including the header is important. The length desired is measured from the engines exhaust flange to the tuned pipe where either the cones meet (maximum pipe diameter) or in a band pipe, where the second cone begins to taper off. (starts to get smaller in diameter)

For the common 25cc Zenoah engine and many other similar engines that run with close specifications, the best value to start at is at 320mm ( 12-5/8″) or longer. Once set at this length, it is ideal to run the engine warm and drive the boat at wide open throttle. Note the performance you achieve. This is best done using the methods explained in the determining speed page. When the hull is brought back in the tuning process begins. After each run it is best to shorten this length by increments of 3mm – 6mm. (1/8″ – 1/4″) After shortening the pipe it is best to run the hull again and note performance. Continue to follow this process until the performance drops off. You may notice performance drop off in the corners or overall top speed. It is up to the driver to select the best desired performance.

Gas Boat Tuned Pipe Tips

It is important to keep in mind that different props or setups will slightly change the tune of the pipe. It’s best to use a prop that performs and handles well prior to the tuning process. Also keep in mind the characteristics will change after the tuning process.