A Dynamometer is a device that provides a measurable load (force) on an engine. This International Dyno service of Marine Dynamometers provides a load for marine outboards and I/O's to closely simulate actual on-the-water operation. Dyno load measurements can be used to evaluate an engine's full throttle power and acceleration.
An engine's operating characteristics are completely different during no-load (static) running than they are during loaded (dynamic) running. It would make sense that you should do your tuning and troubleshooting on an engine that is comparably loaded to actual on-water conditions. Many customer complaints do not show up on an engine operating with no load.
It takes 5-15 minutes to connect the Dyno and run an engine test. Compare this to the time it takes to water test an engine. Also consider the fact that you can Dyno-test day or night, regardless of weather, and in your shop where your tools and parts are always within reach. Your liability exposure for worker's comp and the customer's property is drastically reduced. To verify your solution to the engine problem, you would need to re-water test. The Dyno would only take 5-10 minutes.
Test tanks are fine for the lower horsepower engines and a limited amount of applications. Few engines can be run at full throttle in a tank with a test prop without aeration and prop cavitation. This will cause engine surging. A full-line dealer would need a wall full of test props. Also, test tanks are not portable.
Dyno testing will not harm an engine. All you are doing is duplicating normal operating conditions in your shop.
Since a typical Dyno test generally takes less than a few minutes of full load operation, a flushette which supplies water to both sides is sufficient. For extended running or poor water supply conditions, something as simple as a small cattle watering tank (or even your test tank) can be used to supply engine cooling water.
We measure engine output as pressure (P.S.I.) buildup in the Dyno. We provide charts for all engines listing their output at specific full throttle RPMs. For evaluating changes and engine improvements, at a specific RPM, an increase in PSI means an increase in power output.
Simply, our method of reading pressure is much less expensive. A pressure reading serves as a reference point, as does a horsepower reading. Our method of measurement makes the Dynamometer affordable to every dealer. It is important to realize that when manufacturers assign a horsepower rating to an engine, it is done under optimal conditions (a specific altitude, temperature, barometric pressure, and humidity level). This, coupled with the fact that they are allowed a +/- 10% margin of error in production, means that you would rarely see an exact match to the rated figure in real-world conditions.
There are models for most standard production outboards and I/O's ranging from 35 HP and above.
The only routine maintenance suggested is a yearly change of the hydraulic fluid.
By enabling you to effectively speed up service work and drastically increase your troubleshooting accuracy. Costly "comebacks" are virtually eliminated. Potentially bad trade-ins can be identified on-the-spot. But the most obvious means of increasing revenue is by implementing a "Dyno Tuning" charge. Most shops charge a flat fee of $25.00 to $50.00 to simply connect the Dyno to the customer's engine and run it. Multiply the number of engines you service by your "Dyno Tuning" fee and you will quickly see why the Dyno pays for itself.
By comparing your initial Dyno reading to the specifications published in our Performance Guidelines booklet for that particular engine, you can determine if it's producing proper full throttle power. If it isn't, or if you are making modifications for additional performance, your initial Dyno reading serves as a reference point. For each subsequent Dyno run you can actually measure the increase or decrease in power resulting from your work. The Operator's Manual also contains tuning and diagnostic hints with general pressure loss readings typically resulting from problems such as a dead cylinder, power pak breakdown, high-speed miss, and more.
Explain to them the benefits of testing and confirming their engine's performance under loaded conditions in the shop. Explain the hourly labor charges they are saving versus an on-the-water test. Explain how you can actually measure their engine's performance and provide them with before and after Dyno readings if you wish. The simple fact that you have a Dyno suggests that you have a capable and progressive shop.
There are a few common reasons technicians may resist using the Dyno: some prefer to take the boat for an on-water ride; a new employee may not yet be familiar with Dyno operation; and some technicians are simply set in their ways, having always serviced engines without a Dyno. As an owner, stressing the need for faster customer service and measurable productivity gains goes a long way in making the transition. Some dealerships pay mechanics by the job rather than by the hour, which naturally encourages efficient use of the Dyno.
Many decision makers want to wait for some undefined level of sales or productivity before investing in a Dyno. The fact is that a Dyno will help you achieve that goal. You can't charge for a tank test — but you can charge for a Dyno test. Forget, for a moment, all the troubleshooting and cost-savings benefits and calculate one year's revenue from Dyno-Tuning charges alone. You'll see why we say a Dyno doesn't cost — it pays. In reality, what costs you is the lack of a Dyno. You can purchase a Dyno from one of the major engine repair manufacturers at a substantial discount, or use our purchase plan for as little as $142.00 a month. Call for details.
A dynamometer is an apparatus that measures mechanical force, speed, or power of an engine. In a typical engine/dynamometer test cell, the end of the engine crankshaft is coupled to the dynamometer via couplings and a drive shaft. When the engine is running, the dynamometer exerts a braking force on the engine. Sensors measure engine speed and torque, and from those values the dynamometer calculates engine power output. This allows you to reproduce a desired speed or torque under controlled conditions — in other words, simulating "on the lake" conditions right in your shop.
A dynamometer provides RPM and torque readings that you simply can't accurately obtain on the lake. These measurements can determine whether a boat motor is operating within the engine manufacturer's specifications — giving you documented, repeatable data every time.
A dynamometer can detect and simulate 93% of engine load conditions that an on-water test provides. Low idle speed, mid-range, and full throttle testing can all be accomplished in a controlled shop environment. A small percentage of issues — such as boat hull changes or conditions unrelated to the engine — cannot be detected with the Dyno and may still require a lake test.
Dynamometers have been around for many years and are simple to use. There are straightforward operating instructions for attaching the dynamometer to the boat engine. Two easy-to-read gauges provide RPM and torque readings. A performance guidebook cross-references these readings into measurements that indicate whether the engine is performing within the manufacturer's specifications.
Most dynamometer tests are quite short — usually two minutes or less of actual run time. Including setup, an experienced mechanic can complete the entire dyno test in thirty minutes or less. That's considerably less time than a typical on-water lake test.
Although it depends on how far your dealership is from the lake, our independent survey indicated that most on-water testing takes two hours or more if the boat has to be trailered to the lake. Compared with a typical dynamometer test, the time savings are substantial.
One of the many advantages of the Dyno is that it's right there in your shop — the same place all your other tools and testing equipment are located. It's convenient to use and greatly increases mechanic productivity. In addition, any replacement parts needed for repairs are also close at hand or can be promptly ordered without losing time to travel.
The lake is certainly great for having fun, but it's not very efficient for diagnostics. A lake does not provide your mechanics with any readings to help them diagnose engine problems. Lake conditions are not consistent from day to day and do not provide a controlled test environment, making it impossible to get repeatable, reliable measurements.
A small water tank can help with low engine idle speeds only. Cavitation problems make mid-range and full throttle testing inaccurate in a tank. A large water tank can solve some of these problems, but space requirements and environmental concerns often make it impractical. Like the lake, a water tank test provides no diagnostic readings. A Dyno test done in the shop is a far more efficient and informative alternative.
Absolutely. Many marine dealer owners require that every trade-in be tested on the dynamometer. The RPM and torque readings indicate whether the engine is operating within the manufacturer's specifications. One dealer reported paying for their entire Dyno with savings from a single trade-in evaluation that identified a lower unit problem before the purchase was finalized.
Yes. Many marine dealer owners use Dyno readings to show prospective buyers documented engine performance results. If the motor — typically half the cost of the boat — is operating within specifications, you can confidently ask a premium price. Conversely, poor Dyno readings may indicate the resale price should be adjusted accordingly. Testing used boats on trade-in ensures your resale pricing accurately reflects the actual condition of the engine.
Dynamometers have been around since the early 1900s and use many methods for inducing a braking force — water, hydraulic, eddy current, and others. Hydraulic fluid has been found to provide a more stable medium for measuring engine characteristics. More stability means less breakdown, lower maintenance costs, and better testing results. Hydraulic fluid-based dynos deliver more consistent results and a longer service life than water-based dynamometers.
To determine the horsepower of an engine you connect it to a dynamometer. The dynamometer places a load on the engine and measures the amount of power produced. It applies a braking force at various RPM points and records the torque at each level. Using the standard formula HP = (Torque × RPM) / 5,252, the dynamometer converts those torque measurements into a horsepower figure at each engine speed, giving you a complete power curve for the engine.
To convert pound-feet of torque to horsepower, use the formula: HP = (Torque × RPM) / 5,252. The number 5,252 comes from combining several unit conversions: 1 horsepower is defined as 550 foot-pounds per second, and engine speed in RPM must be converted to radians per second. For example, an engine producing 300 lb-ft of torque at 4,000 RPM puts out (300 × 4,000) / 5,252 = 228 horsepower at that RPM. Plotting horsepower across various RPM values gives you the full power curve for the engine.
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