How to increase the power of a boat motor, PLM venting

A pleasant driving experience requires a fast engine. The desire to get the most out of an engine appears in every inveterate shipowner or beginner who is dissatisfied with a cheap purchase. A reasonable question arises: is it possible to increase the efficiency of a gasoline outboard motor?

This is possible, but a lot depends on the model. On many engines (Honda, Mercury, Yamaha, Suzuki, etc.), manufacturers often install limiters, despite the obvious excess of power. Such a marketing ploy allows you to sell different modifications of the same engine for the Russian market. For example, at the factory they take a 15 hp motor. and install limiters. Its power is reduced to 9.9 hp, and now it does not require registration with the GIMS from the owner. It costs a little less, although the parts inside are the same as for the more powerful version.

Breathering is a way to increase the power of a boat motor by removing the restrictors. To “strangle” means to remove the restraints on the motor. As a result, the PLM begins to work in full force. Different manufacturers choke their motors in different ways: some put different firmware on the microchip, some change several parts, some just install a switch.

In addition to airbrushing, there are also other ways to increase horsepower. The final method of increasing power depends on the type of engine.

By the way, in our catalog, using filters, you can immediately select a motor that is suitable for power and do not waste time on ventilating! Select a boat motor by power

Valve petals

Let's look at the simplest option. First, we inspect the carburetor valve to find out if it has a throttle valve limiter. If the “window” opens completely at maximum thrust (80 degrees), then there is no obstacle. If the engine is not working at full strength, then you need to find out what is stopping it. To do this, we look for the valve hidden under the carburetor.

Valve petals are rigid plates bent inward. In two-stroke engines they are placed next to the main cylinder. If it is noticeable that the petals are somewhat pressed inward, then press them outward. But you can’t go too far, as there is a risk of the petals falling off. The bend will provide a greater flow of fuel. This is what we need. A nuance: fuel consumption increases, which will cost the ship owner a pretty penny. In addition, engine noise increases.

Most Popular

The most popular blown motor today is the 9.9 - 15 hp model. From the Japanese manufacturer Yamaha. There are a lot of Chinese analogues of this model on the Internet that are already inflated to maximum power. The reason for this is the new law, which allows you to drive a small boat with an installed outboard engine up to 8 kW (10 hp) without a GDP license and without registration with the GIMS

For example:

Hidea HD9.9FHS,
Mikatsu M9.9FHS,
HDX 9.9FHS,
Sea Pro OTH9.9.

Well, or in other words, identification marks and a nameplate marked 9.9 are pasted onto the 15 hp engine. Russian suppliers of outboard motors immediately realized that this was an excellent step towards superiority over their competitors. And they began to order engines with increased power, but with markings that would qualify for driving engines without a GDP license and without registration, namely 9.9 hp. Thus, this model does not need to be perfumed if it is made in China.

If you are going to buy a Chinese engine with the maximum permitted power without registration, then you can safely take 9.9. Any Chinese analogue of this engine will have an output of 15 hp. There is no need to ventilate the engine. And it’s also worth taking this into account when buying a boat.

Carburetor

The power of two-stroke engines can also be increased by working on the carburetor. To do this, perform the following steps:

dismantle the carburetor;
increasing the size of diffusers. Drill a hole no larger than 0.1 mm;
putting the carburetor back together. We adjust the dispenser;
adjust the ignition angle. Attention: we adjust the ignition angle with advance. It is also necessary to change the spark plugs.

Working with carburetors and diffusers requires experience. You will have to completely replace the elements. This method is unlikely to be suitable for beginners. It is better to seek help from professionals. Any manipulations with the insides of the engine carry certain risks.

How can you increase the speed of a boat without changing the engine itself?

Following absolutely simple rules can not only increase the desired speed of the boat, but also save a significant amount of fuel.

Basic rules for increasing boat power without changing the engine:

Keep the underwater part of the boat under control.
Remove unnecessary things from the watercraft (unnecessary cargo).
Monitor the condition of the propeller.

The first step is to carefully monitor the condition of the underwater part of the boat. It is recommended to systematically clean any formations. You should also not forget about the drive. After all, it is the underwater part of the craft that has a great impact on slip resistance. It might seem like a small thing, but it plays such a significant role.

We do not ignore the external condition of the cockpit and internal premises. We remove all unnecessary things and then systematically carry out cleaning. We leave only the essentials, especially those related to safety. We mercilessly take out the rest of the trash.

When refueling a boat, you should not skimp on quality fuel and oil. This will only reduce the amount of horsepower. In addition, the engine must be kept in perfect condition. The condition of the propeller influences the speed development no less than anything else.

Chips on the edges of the blades are unacceptable.

This will take away the desired power and increase fuel consumption. In addition, it is worth considering the parameters of the screws. They are selected separately for each model. We can say that the speed of the boat is largely influenced by a properly selected and installed propeller rather than by the ship’s engine.

The main details affecting the performance of the propeller:

Propeller pitch. This value shows the movement of the screw along the axis per full revolution. Propellers with large pitches convert only a small portion of the motor's power into quality energy that propels the boat.
Diameter and disc ratio. These indicators characterize the area of the blades and indicate the full operation of the propeller.
Finishing the propeller. All screws need finishing. If a light propeller does not remove the built-in power from the motor, then it is recommended to increase its pitch. If it is impossible for the engine to develop normal speed due to a heavy propeller, the solution will be to reduce the pitch or diameter.

It is much easier to fine-tune heavy propellers, since trimming the blades is an easier process than changing the pitch. Before starting fine-tuning, the motor must be run in and adjusted by a specialist.

Chip firmware

Some 4-stroke engines do not have any plugs or restrictors. This does not mean that the engine is working at full capacity. It's all about the electronic filling: the characteristics are regulated using a special chip. There's not much you can do here with your hands. Working with electronics requires knowledge and experience.

You can look for a special service or a craftsman. They will reflash and check the motor. There is no point in working with electronic components on your own without programming skills.

Perfumed up to 20hp. 2-stroke without registration

But there are still more powerful options from Chinese manufacturers and are also subject to Russian restrictions on driving a motorboat without a license and registration, which there is no point in suppressing. This is a 326 cm3 engine. This motor has an output of 18-20 hp. and is an 80% copy of the 18hp model. from the Japanese manufacturer Tohatsu.

Russian entrepreneurs followed the beaten path and ordered this motor from China with the 9.9 marking and an ENDURO or PRO prefix.

For example:

Hidea HD 9.9FHS PRO or Mikatsu M9.9FHS ENDURO.

The Japanese have the same option, but only in terms of external characteristics. That is, the engine is 9.9, 15 and 18 hp. produced under the Mercury, NS Marin, Tohatsu brands are absolutely identical in appearance, but the volume of the internal combustion chamber differs. On one engine it is 247 cm3 (Mercury 9.9MH or NS MARINE NM9.9), and on the other it is 294 cm3 (Mercury 15MH, NS Marine 18).

The smaller model with a volume of 247 cm can also be throttled by replacing the gas cam plate with the plate from the older model. Due to this, the throttle valve opens a little more, which gives an extra flow of power and speed.

Is there a need to modify the engine?

If the boat owner does not have enough speed while moving along the river to get on plane, this does not mean that the boat needs a more powerful motor. The trim may need to be adjusted. To do this, you need to evenly distribute the load in the cockpit so that the angle between the surface of the water and the keel line is about 4 degrees. If the trim is set correctly, then you need to check the engine operation settings. If the propeller is too deeply immersed in water, then as a result of a significant increase in the coefficient of profile drag in the underwater part, as well as an increase in the back pressure of water on the exhaust gases, the engine power is noticeably reduced. If the propeller is not deep enough into the water, then when the motor operates, a space consisting of air and water vapor is formed at the backs of the blades. As a result, the efficiency of the power unit decreases. Another reason that the watercraft does not develop the desired speed on the water is the replacement of a broken original factory propeller after a breakdown with a non-original one.

Rules

Before you start making mechanical changes to the engine, it's a good idea to optimize some other parameters of the boat that may affect its speed:

Try to sort out the things you carry with you but don't use on the water. For example, if possible, leave transom wheels on the shore. Assess the gas tank - is it too big? Or maybe one of the two anchors can be replaced with a floating one or eliminated altogether.
Pay attention to the screw. Any chips, cracks, or roughness lead to a decrease in buoyant force. This screw needs to be replaced or ground. Don’t forget that in addition to standard ones, there are “cargo” and “high-speed” propellers on sale. To reach the glider, you can experiment with a 4-blade propeller. Installing a steel propeller will increase engine efficiency due to the thinner blades.
Adjust the position of the motor relative to the transom. It is advisable to raise the motor as high as possible. You may even have to use special spacers for this. This will reduce the resistance of the deadwood boot. But do not overdo it so that the propeller does not catch air during waves and turns.
Level the boat using proper weight distribution. It is better if there is a slight trim towards the stern. When underway, the engine must be in such a position that the propeller axis is parallel to the surface of the water.
Check the pressure in the cylinders. This is one of the main factors influencing the maximum speed of an inflatable boat. The balloons are inflated until they begin to ring. Do not forget that when launching into the water, the pressure will drop due to cooling of the air.

How to increase the power of two-stroke outboard motors

To maximize engine power, you need to perform several operations, each of which will give a certain percentage increase in horsepower, along with an increase in fuel consumption.

Check to see if the throttle limiter is stuck.

How to increase the power of four-stroke outboard motors

4-stroke outboard motors will accelerate using the same methods as 2-stroke outboard motors. Limiters, valves, jets.

But there are a few additional points:

After all the procedures, it is necessary to reconfigure the valve clearances of the gas distribution mechanism. The clearances of the inlet and outlet valves need to be slightly increased due to the fact that the volume of the combustible mixture has increased. It is also advisable to increase the lead angle by a few degrees.
In some high-performance engines, you won't find any throttle limiters or suppressed reed valves. This means that the engine parameters are regulated by the built-in chip. And this is a completely different song. A wrench won't work here. It is necessary to perform chip tuning of the electronic control unit (ECU). The topic is young and little explored. In any case, it has not yet become as widespread as for cars. Therefore, it is better to contact the service. You can try looking for specialized software on Chinese websites.

How to increase the power of a boat motor using examples

Adding one horsepower to the popular Tohatsu 5 4-stroke engine, turning it into the Tohatsu 6, couldn't be easier. There is no need to resharpen anything. You order a carburetor for a Tohatsu 6 outboard motor from a foreign online store (it’s cheaper there than in the domestic store). You can search using the words “tohatsu 6 hpcarburetor”.

Once you have the carburetor in your hands, change one for another. And you are the owner of a 6-horsepower engine. This pleasure will cost $180 plus shipping. The difference between the Tohatsu 5 and 6 engines is almost $400. Either way, you'll save something. But you can also drill.

Due to the fact that the Yamaha 5 outboard motor has no analogues with forcedly reduced technical characteristics, the option of replacing the carburetor will not work. But you should look for the throttle limiter, just like the reed valve. Eliminate the first one, and squeeze out the petal in the second device.

Despite the fact that this engine model has no followers and there is no reason to save power, Japanese and European manufacturers still set restrictions due to the requirements of environmental legislation, which in many countries prohibits the use of engines at full power due to increased carcinogenic emissions. substances into the atmosphere.

Basic recommendations

Before you decide to disassemble the engine and modernize it, you need to try to solve the situation with less drastic methods. Experts recommend adhering to the following rules:

Do not take extra cargo with you on the road. For the trip you need to prepare only the most necessary things. The gas tank should not be too bulky or heavy. If possible, it is better not to take transom wheels.
Check the pressure in the cylinders. Refilling of products should be carried out until they begin to ring. Once the boat is on the water, the air will gradually cool and the pressure will drop slightly. This factor also affects the speed of the boat.
Adjust the position of the motor relative to the transom. The engine needs to be raised higher, it is advisable to use auxiliary spacers. You must not overdo it, otherwise the blades will spin in the air when pitching.

Special attention should be paid to the screw. You should regularly check for irregularities, cracks, chips and any other deformations that may negatively affect the displacement capacity of the unit. Most often, problematic screws are replaced or simply sanded well. In order for the boat to glide, you need to install a four-bladed propeller. When installing a metal part, you can slightly increase engine efficiency by reducing the thickness of the blade.

Source

Increased power of four-stroke engines

To try to stifle a four-stroke internal combustion engine, you must:

Adjust the valve clearances of the mechanism for distributing gases in the engine in such a way as to increase the flow of the incoming combustible mixture into the combustion chamber.
In more powerful and modern engines, in order to further increase their performance, the master needs to reflash the electronic unit. This operation is carried out only for four-stroke power units. This can only be done by a specialized repair service for this equipment.