The question of what the real fuel The 100 horsepower outboard motor is a concern for every PVC boat owner before buying or navigating. The numbers in manufacturers' advertising brochures are often optimistic, but the harsh reality of water use makes its own adjustments. The final appetite of the engine is influenced by many factors, from the weight of the boat's hull and propeller to the quality of gasoline and wind speed.
In this article, we will analyze in detail how many liters of gasoline per hour “eats” Yamaha, Tohatsu or Mercury You will learn why data-sheet figures may differ from the actual readings, and learn to calculate the necessary fuel for a long trip.
Understanding the mechanics of combustion in cylinders will help you not only plan your budget for the season, but also avoid dangerous situations when gasoline runs out in the middle of a reservoir. efficiency your engine's work.
Factors Affecting Gasoline Consumption
The first thing to consider when calculating the range is the type of engine. Two-stroke engines (2T) are traditionally considered more voracious, as part of the fuel mixture is simply released into the exhaust system along with the exhaust gases. In addition, oil must be added to gasoline, which changes the overall energy value of the mixture.
On the other hand, modern four-stroke (4T) the units work on the principle of car engines, providing a more complete combustion. However, there is a nuance: the weight of the 4T engine is much higher, which causes the boat hull to burrow more into the water at low speeds, increasing drag.
⚠️ Note: Do not confuse theoretical consumption with real. In practice, the difference between 2T and 4T engines of one power can be as little as 10-15%, rather than the stated 30-40%, especially at high revs.
The second critical factor is aerodynamics And the boat-motor hydrodynamics, the extra equipment on board, the number of passengers, even the algae that fills the bottom, creates additional resistance, and the higher the resistance, the more gas you have to add to keep up.
And the propeller is also important. If you're not fitting the propeller's pitch correctly, you're not getting the engine to its optimum speed or you're oversteering. You're losing speed at a high flow rate, you're at risk of overheating in the second. piston-group.
Consumption in different operating modes
To get an objective picture, you need to look at the dynamics of fuel consumption. Engine modes change the numbers on the meter dramatically. Manufacturers often give averages, but we need specifics for route planning.
Nana idle The engine consumes the minimum amount of fuel needed to keep the ignition and lubrication systems running, which usually ranges from 0.5 to 1.0 liters per hour for engines of this capacity, which is important to consider if you plan to drift for a long time while fishing.
- 🚤 Idle passage: 0.5 - 1.2 l / h (depends on the setting of the carburetor).
- 🐢 Economical move (3000-3500 rpm): 10 - 15 l / h (optimal mode for long-distance crossings).
- 🚀 Full gas (WOT): 35 – 45 l / h (maximum power, high wear).
Regime. gas-filled (Wide Open Throttle) is extreme load, and in this mode, a 100-horsepower engine can consume up to 45 liters per hour, especially if it's a two-stroke model without a direct injection system, and running long hours in this mode not only depletes the tank in an hour, but also reduces the engine life.
The most efficient speed/consumption ratio is 75-80% of the maximum power, and that's where the boat goes into planing, and the water resistance drops dramatically, allowing you to reach high speed with moderate gasoline consumption.
Comparison of two-stroke and four-stroke models
The eternal dispute between the two-stroke and four-stroke proponents in the 100 hp segment requires detailed analysis. If you compare classic 2T carburetor engines with modern 4T engines, the latter gain in efficiency by about 20-30% in the combined cycle.
However, if the matter is two-stroke direct-injection engines (E-TEC, OptiMax, JetDrive), things are changing, and these fuel-consumption engines are almost as good as their four-stroke counterparts, while still keeping weight down and better throttle. keynote when choosing a motor for light aluminum boats or inflatable PVC.
| Characterization | two-stroke (Carburetor) | two-stroke (Injector) | four-stroke |
|---|---|---|---|
| Full gas flow rate | ~40-45 l/h | ~32-36 l/h | ~30-35 l/h |
| Expenditure on cruise | ~20-25 l/h | ~14-18 l/h | ~12-16 l/h |
| Motor weight | ~140-150 kg | ~150-160 kg | ~160-175 kg |
Four-stroke engines also benefit from environmental friendliness and noise, which is a crucial factor for many anglers. repair complex valve system and timing 4T engine will cost more than replacing the piston in a simple 2T.
Why is 2T injection more economical?
The direct injection system delivers fuel directly to the cylinder at high pressure only at the right time, eliminating the release of unburned mixture into the exhaust.
How to calculate the fuel supply for the hike
It's not just drawing a line on a map, it's a precise mathematical calculation, and a mistake in your calculations can lead to a situation where you're a few kilometers away from the shore and the tank is empty. Travel time × Consumption + 30% reserve.
Thirty percent stock is the gold-standard It's necessary in case of headwinds, strong currents or the need to change the route because of a storm warning. Never plan a back-to-back hike.
☑️ Fuel reserve calculation
For example, if you go to a fishing point 70 km, and you go at 35 km / h, it takes 2 hours. At 20 liters per hour, you need 40 liters. Add 30% (12 liters) and get the required volume of 52 liters. Round up to 60 liters for peace of mind.
⚠️ Attention: Always keep in mind the opposite current when calculating. If you go up the river, the real speed relative to the bottom will be lower and the engine's running time will be higher, which will increase the overall flow rate.
Ways to reduce fuel consumption
There are a number of technical and organizational measures that can significantly reduce the appetite of your 100-horsepower engine. maintenanceDirty candles, a clogged fuel filter or an incorrectly exposed ignition advance angle can increase gasoline consumption by 10-15%.
The next step is to optimize the load. Spread the load in the boat so that it goes smoother. If the boat's nose is too upside down, the water resistance area grows, and the engine has to work harder. Try to shift the load forward a little bit or change the angle of the day-woot (trim).
- 🔧 Timely replacement of candles: ensures stable combustion.
- 🧹 Underbody cleaning: removes algae and barnacles reducing drag.
- ⚓ Right screw: matches the boat weight and usage style.
Avoiding abrupt jerks with the handle of the gas is also a good idea. Smooth acceleration allows the engine to run at optimal speed without enriching the mixture. Abrupt opening of the throttle often results in a short-term but powerful release of excess fuel.
Use a GPS tracker or navigation app on your smartphone to track average speed and flow in real time, which will help you find the most economical engine mode for your particular boat.
Technical condition and economy
The health of the engine directly affects the owner’s wallet. Compression If the compression is down, the engine loses power and requires more fuel to do the same job, and it should become a habit to measure the compression regularly.
The fuel system also requires attention. Older gasoline that has lost its properties, or the presence of water in the tank leads to unstable operation, use only fresh fuel with an octane number recommended by the manufacturer (usually AI-95 or AI-98), and quality additives if the engine has been standing for a long time.
Pay special attention to the condition of the lower unit. Even a small dent on the lower unit nozzle or a damaged anti-cavitation plate can disrupt the flow of water and air, reducing the efficiency of the screw. Visual inspection before each season is mandatory.
Regular maintenance and clean propeller can save up to 20% of fuel per season, which at current gasoline prices fully pays off the cost of maintenance.
How often do you need to change fuel filters to save money?
For heavy use (more than 100 hours per season), it is recommended to change the fuel filters-sludges every 50 hours, and fine cleaning - once a season or every 100 hours. A clogged filter creates a vacuum in the system, the pump pump pumps more intensively, and the mixture becomes poorer, which can lead to overheating.
Does the water temperature affect the flow rate?
Yes, it does. In cold water, the engine goes to operating temperature faster, but the water density is higher, which increases resistance. In warm water, the motor can run a little more efficiently, but the risk of overheating is higher. The optimal temperature of the coolant is critical for proper mixing.
Should I switch to four-stroke for the sake of saving?
If your annual coast down exceeds 100 hours, the transition to a modern four-stroke engine will pay off in 3-4 seasons due to fuel and oil savings. For rare weekend trips (20-30 hours per year), the difference in consumption will not be so noticeable against the background of the high cost of the engine itself.
Which screw to choose for minimum consumption?
A screw with a pitch such that at full gas (WOT) the engine goes to the upper limit of the recommended range of revolutions (for example, 5500-6000 rpm). If the engine does not twist, the step is large (overload), if it twists, it is small. The correct step ensures maximum efficiency.
Is the consumption of 10 liters per 100 hp realistic?
The consumption of 10 liters per hour for a 100-horsepower engine is possible only in the trolling mode at minimum speeds (about 1000-1200 rpm). In the planing mode (3500+ rpm), the flow rate will always be higher than 15-18 liters, regardless of the manufacturer's assurances.