Finding the optimal power plant for a small PVC boat or a light metal boat often leads the owner to the middle of 8 horsepower. This parameter is not accidental: it allows you to plane with one or two passengers on board, while maintaining an acceptable fuel consumption and weight of the unit. boat-engine 8 l It is considered one of the most popular requests among beginners and experienced fishermen who value mobility.
The modern market offers a huge variety of models, where the technical specifications can be radically different even with the same passport power. two-stroke and four-stroke The engine is not just a matter of price, it's a matter of determining the style of your boat operation: Two-strokes are easier and easier to maintain, while four-strokes are quieter, more economical and more environmentally friendly.
In this article, we will discuss all the nuances that you need to consider before buying. You will learn about the design features, nuances of running and the specifics of setting up the carburetor for different operating conditions. The right choice is to ensure that your boat will confidently go to the plane and delight in reliability for many seasons.
Technical features and working principle
The main difference between engine types lies in the combustion cycle of the fuel mixture. two-stroke In the model, the process takes two strokes of the piston, which provides a high specific power per kilogram of weight, which makes them ideal for boats where every kilogram on the transom makes a difference, the mixture of gasoline and oil in these engines is prepared in advance or fed through a separate tank, burning with the exhaust gases.
Four-stroke units operate on a more complex scheme, where the engine is lubricated independently of the combustion of the fuel, thanks to an oil crankcase system, which eliminates the need to mix gasoline with oil by hand. Four-stroke engine It works much quieter and more stable at low speeds, which is critical for trolling fishing or quiet walks.
⚠️ Attention: Never run a two-stroke engine without adding oil to the gasoline (unless the model has an E-TEC separate oil supply system or analogues). running on pure gasoline will lead to piston group bullies and overhaul in a few minutes.
You should also consider the ignition and carburetion system when choosing. CDIThis is a stable spark, even when the battery is discharged, and carburetors with petal valves allow better dispensing of the mixture in different modes of operation, increasing the efficiency of combustion.
What is the difference between a lower unit and a lower unit with an elongated leg?
lower unit is the bottom of the motor, submerged in water. The elongated leg (L) is designed for high-transe boats or for mounting on a pendant to keep the screw deeper in the water, avoiding capture of air on the wave. The standard leg (S) is suitable for most inflatable boats.
Two-stroke vs. four-stroke: the eternal dispute
Choosing between these two types of engines is often a stumbling block: Two-stroke engines are about 30-40% lighter than their four-stroke counterparts. For an inflatable boat that has to be dragged to the water by hand, this difference can be decisive. They are also easier to transport: they can be transported on the side without fear of oil leaking.
Four-stroke engines benefit in efficiency and resource. They consume less fuel per kilometer and require less maintenance. However, they often weigh more than 30-35 kg, which makes them less convenient for frequent carrying. If your boat is stored on water or has a wheeled transom, a four-stroke will be a more comfortable solution.
- 🚀 Dynamics: Two-tacters gain momentum faster and go out on plane.
- 🔇 Noise: Four-strokes work quieter, which is important for fishing.
- ⛽ Expenditure: Four-stroke engines are more economical by 20-30%.
- ⚖️ Weight: Two-stroke models are much lighter (about 20 kg vs. 35 kg).
There's also a nuanced environmental issue, where there are restrictions in some regions on the use of two-stroke engines due to unburned oil emissions. 8 hp engine. You need to clarify the local rules of operation of small vessels.
Overview of popular models and manufacturers
There are many brands on the market, from eminent Japanese giants to affordable Chinese counterparts. Leaders in the 8 hp segment are traditionally considered to be the leaders of the industry. Tohatsu, Yamaha and SuzukiFor example, the Tohatsu MFS8C is a standard of reliability among four-strokes, known for its thrust and survivability.
Chinese manufacturers, such as Hidea, Parsun or Sea-ProOften their engines are copies of time-tested Japanese models (such as Yamaha or Tohatsu), making it easier to find parts. However, the quality of casting and assembly can vary, requiring more thorough pre-sales preparation.
| Model | Type | Weight (kg) | Features |
|---|---|---|---|
| Tohatsu MFS8C | four-stroke | 26.5 | Electric starter (opt.), quiet |
| Yamaha 8FMHS | two-stroke | 21.0 | Lightweight, reliable carburetor |
| Hidea HD-F8FHS | four-stroke | 26.0 | A copy of Yamaha, affordable price |
| Suzuki DF8A | four-stroke | 26.0 | Electronic injection (opt.) |
When choosing a specific model, pay attention to the presence of a forced cooling system. thermostatIt allows the engine to warm up faster and operate in optimal temperature, which is especially important for four-stroke units.
breaking in: the pledge of a long life of the engine
The new engine break-in procedure is critical to creating the right gap between rubbing parts, and ignoring this step can reduce engine life by many times, typically taking 10 to 20 hours to run, depending on the manufacturer's recommendations.
In the first hours of operation, it is not recommended to give full gas. The engine should operate at variable speeds, mainly in the range of 30-50% of the maximum power, this allows the piston rings to rub against the cylinders without overheating and bulldozing.
☑️ Checklist of proper breaking in
⚠️ Attention: When running a two-stroke engine, watch the color of the exhaust. If the smoke becomes whitish and very thick, the proportion of the mixture may be disturbed or the quality of the oil is low. Black smoke indicates an over-enrichment of the mixture.
Four-stroke engines must change oil after the first 5-10 hours of operation, during which time metal shavings from rubbing parts enter the oil. Oil replacement At this point removes the abrasive particles and prolongs the life of the motor.
Carburetor setting and fuel consumption
The correct setting of the carburetor affects the engine's handling and efficiency. Factory settings are usually averaged, but may require adjustments for a specific propeller and operating conditions (height above sea level, air temperature).
Adjustment is done using screws of quality and quantity of mixture. However, if you do not have experience, it is better to entrust this operation to the service center. Incorrect setting can lead to overheating (poor mixture) or candles coking (rich mixture).
To fine-tune the carburetor, use a thermocouple or a special exhaust indicator. Visually determining the optimal mode is difficult, and the risk of damaging the piston group is high.
Fuel consumption of the engine 8 hp on average is:
- 🐟 Idle passage: 0.4 - 0.6 l/h.
- 🚤 Trolling (3-4 km/h): 0.8 - 1.2 l/h.
- 🚀 Full gas (plane): 2.5 - 3.5 l/h.
These figures are relevant for a properly fit engine with a well-fitting propeller, and using a large-step propeller can increase consumption and reduce maximum revs, preventing the motor from reaching full power.
Transport and storage
One of the main questions owners have is how to transport the engine correctly. Four-stroke units are strongly recommended not to be placed on the side or upside down without prior preparation.
If you need to put the four-stroke on your side, do so only on the side opposite to the air filter, and preferably after completely draining the oil or using a special transport position (if provided by the design).
The order of conservation for the winter:1. drain the fuel from the tank and develop the residues in the carburetor.
2. Replace the oil (for four-stroke).
3. to treat the external surfaces with anticores.
4. Store in a vertical position in a dry room.
With prolonged storage, it is recommended to periodically (once a month) scroll the engine shaft manually so that the lubricant is distributed to the nodes and prevent corrosion.
The main storage rule: clean gasoline with a stabilizer or a completely dry tank will prevent the formation of resins in the carburetor during the wintering.
Frequently Asked Questions (FAQ)
Will the PVC boat go to plane with an 8 hp engine?
Yes, most PVC boats with a length of 3.2 to 3.6 meters with one adult (up to 90-100 kg) confidently go to the plane with an 8 hp engine At full load (2 people + cargo), plane is possible on boats with a hard or inflatable floor of NDNDND with a length of 3.4 meters.
Which screw is better to choose for the engine 8 hp?
A standard propeller usually has a pitch of 7-8 inches. For heavy boats or trolling, it is better to take a screw with a smaller pitch (6-7 inches) - this will increase traction. For light boats and high-speed walks, you can increase the pitch to 9 inches if the engine allows you to develop maximum revs.
Do I need to register the 8 hp engine in GIMS?
Under current Russian legislation, small vessels with a motor of more than 8 kW (approximately 10.88 hp) are subject to registration. A motor of 8 hp (5.8 kW) is not subject to registration if the total weight of the equipped vessel does not exceed 200 kg.
What kind of oil to use into a two-stroke engine?
Use only quality oils with labeling TC-W3Automotive oils for two-stroke engines are not suitable, as they form a lot of sodium and do not burn completely at low temperatures.