General FAQ

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Since 1958, Go Power Systems has been providing the engine-testing industry with reliable, portable dynamometers and test cell equipment for a variety of industry disciplines. We manufacture and supply testing solutions for high-output small engines, production and performance automotive, heavy diesel engines, and even aerospace. For 50+ years, we’ve established a customer base that stretches around the globe. Our staff continues to maintain excellent relationships with these industries’ veteran engine testers and industry novices alike. Today, both new and existing customers have come to rely on the durability and repeatability a Go Power Systems portable dynamometer system offers.
Go Power Systems was incorporated with Froude, Inc. in 2002. Froude has been developing and perfecting the absorption of horsepower since 1877 and is a world leader in manufacturing engine and vehicle-testing products. For more details about Froude and information about their testing product lines, please visit
At Go Power Systems, we have a different approach to sales than other dynamometer manufacturers. We are not a conventional sales and service office; rather, we consider ourselves assistant buyers. Our primary focus is to provide our customers with a no-pressure sales experience. We strive to earn trust and establish a relationship through competent sales engineering and understanding of the customer requirement. Using this approach, we ensure a thorough evaluation of the application and deliver an end product that meets and exceeds the customer’s specifications and expectations.
The basic dynamometer test stand consists of a dynamometer, water supply, load control valve system (manual or electronic), and a means to collect the data output from the load cell (torque) and speed sensor (rpm). Other items such as thermocouples, pressure transducers, and flow measuring devices are add-ons that you may not initially need because their requirement depends upon the type of testing you’re conducting. Go Power Systems equipment allows customers to customize their initial system to their primary equipment needs and add items to the system if and when they choose.
Absolutely! Go Power Systems offers a wide array of out-of-the-box packages for all of our dynamometer models; each is fully calibrated and ready for immediate use upon delivery. Our Essential Dynamometer Package (EDP) is very popular; it consists of a portable water brake dynamometer, a DC-200 digital display console, and all of the model-specific ancillary support items necessary to perform manual controlled engine testing. For diesel engine testing, we offer an upgraded EDP-Plus package that replaces the DC-200 console with a GPS-2508 data acquisition system and includes four thermocouples and two analog pressure transducers. Your Go Power Systems sales engineer can help you determine which package offer best suits your testing requirements.
Water serves two purposes in a water-brake dynamometer application: 1) It provides the means by which load (opposing force to the rotation of the engine crankshaft) is applied to the dynamometer, and 2) Water carries away the heat generated by the process of absorbing power.
Generally not. City water systems often have inconsistent water-supply pressure and variances in delivery volume. These factors contribute greatly to the overall performance of the dynamometer. Typically, the pressure from the city is not enough to provide the brake with a supply capable of supporting the maximum absorption capacity. This condition results in a lack of controllability. Insufficient water supply can also contribute greatly to internal wear of the absorbing elements due to cavitation occurring inside the absorption module. Our duty curves supplied for each dynamometer model reflect the absorption performance profile of the brake at the minimum water requirement specification for delivery—both pressure and volume.
Depending on the model/series of the dynamometer you select for your particular application, the water delivery pressure requirement will vary between 45–60 psi or higher.
A typical calculation is 5.5 gallons of water required per brake horsepower (hp) absorbed, per hour. For example, to absorb 200 hp for one hour, you would need 1,100 gallons of water (200 hp x 5.5 gallons of water x one hour of running). This water can be recirculated with the proper equipment. Contact your Go Power Systems sales engineer for details on a semi-closed-loop water system.
Yes. Go Power Systems recommends no more than an 80°F (12°C) inlet water temperature to maintain a maximum temperature rise of 60° depending on the condition of the dynamometer and water quality. We recommend instrumenting both the inlet water supply and the outlet water stream with temperature indication to ensure an overheating conditiondoes not occur. The maximum recommended outlet temperature should not exceed 150°F (51°C) at any time because calcium is released from suspension in water at 160°F (57°C) and begins to propagate on the internal heat transfer surface areas of the dynamometer. Continued operation under this condition can lead to the formation hard-scale coating of the rotors and stators, thereby reducing the dynamometer’s ability to dissipate generated heat. Subsequent failure and costly repairs of the brake can result fro7m this preventable condition.
Go Power Systems recommends maintaining the pH level between 7.4 and 8.4 and the Calcium Carbonate (CaCO3) level less than 150 ppm. Suspended solids should not exceed 400 ppm, and the filtration level should be at or below 140 microns. Y-type and duplex-type strainers are the most common fluid filtration systems and offer the least amount of restriction to flow. They are relatively inexpensive, provide excellent protection for your dynamometer, and help increase the system’s service interval. Failure to use a filtering device on your dynamometer water system can result in damage to the internal components, premature failure, and subsequent cost of repairs. The service life of any water brake dynamometer can be directly attributed to the quality of the water it is supplied with.

Yes, as long you consider the following:

  • The outlet water from all Go Power Systems dynamometers is designed to be channeled to a gravity drain with no restriction. In a semi-closed-loop system, a vented drain tank must be situated near the dynamometer outlet(s). You also need a submersible or externally mounted transfer pump to recirculate the water back to the supply source. Failure to correctly plumb your water system can result in hydraulic lock, back pressure, and general instability issues.
  • The discharge water from the dynamometer is hot when it exits the dynamometer because the process of absorbing power converts the crankshaft rotation energy into heat. Therefore, an intermediate water cooling device must be installed in the line from the gravity drain tank and back to the supply tank. Your Go Power Systems sales engineer can help you determine the cooling requirements for your application.
Antifreeze and ethylene glycol are great to use in water brake dynamometers because its lubricating properties can extend the life of the seals and internal wear. It also acts as a corrosion inhibitor coating all of the internal surfaces. However, because of environmental concerns, you must run a semi-closed loop system if you intend to use either of these fluids. Do not exceed a 50/50 mixture of water and antifreeze or ethylene glycol or frothing will occur in the absorption module. Distilled or soft water may also be used in place of your city or ground-well-supplied water source for makeup water.

An adequate water system is the most important factor to consider for optimal performance, durability, and repeatability of a water brake dynamometer. It is imperative to ensure your system is capable of delivering both the proper pressure and volumetric flow rate to the dynamometer load control valve. Go Power Systems offers Water Delivery System (WDS) packages that are designed and properly sized for each dynamometer model. These systems guarantee that the performance of the dynamometer matches the associated duty curve for the model it is designed to support. A basic water system consists of:

Supply Water Tank: The capacity of your supply water tank is based on:

  • The type of testing you plan on conducting, whether holding values at various steady-state test points or performing brief Wide Open Throttle (WOT) power curve determination runs.
  • The power range you’ll be operating at.
  • The duration of your tests (which dictate how much water you will use).

An over-sized supply tank will help, but if dumping the hot effluent water from the dynamometer directly back into the supply tank, your inlet water temperature will quickly increase as the test continues. This change in inlet temperature causes the density of the inlet water to decrease which changes the dynamometer’s absorption profile. Go Power Systems water brake dynamometers require discharge water to drain unrestricted to a gravity drain point, meaning, the drain must be routed to a drain point lower than the absorber (such as a floor drain).

If discharging to a holding tank, make sure the connection point is below the center line of the dynamometer, but also above the maximum water level of the tank. Refer to the water flow specifications of your specific dynamometer model or consult with your Go Power Systems sales engineer for your specific requirements.

NOTE: To reclaim water for recirculation, a vented drain tank is required to collect the exhausted load water. In a semi-closed-loop system, the dynamometer discharge water cannot be transferred directly back to the supply tank. Remember, you’re using water to absorb the power output of the engine which is converted to heat. Therefore, the dynamometer discharge water must be cooled prior to reuse. An industrial evaporative-type cooling tower is designed specifically for this purpose. Depending upon the application and power absorption requirements, it can be also done in a number of other ways. A more economical means is to have an intermediate cooling tank where the water can settle and cool to ambient temperature or use a series of radiators with electric fans. If your facility has a chiller system, we offer our WDS systems with a plate-and-frame type heat exchanger skid for integration into the cooling circuit. Go Power Systems can provide a water cooling system designed to fit your testing application. Ask your sales engineer for details.

Booster Pump: A centrifugal-type pump with a flat-head profile is commonly used and most reliable for providing adequate pressure and volumetric flow rate to support dynamometer operation. Depending on the model and capacity dynamometer selected, the hp rating for the motor varies. If an engine cooling tower is required, the additional water needed to facilitate this load must be accounted for in sizing the pump. It is always good practice to oversize the water system and its components to allow for future upgrades. We do not recommend using a positive displacement pump because the design of this style pump will continue to build downstream pressure in the event of inadvertently shutting the dynamometer load control valve. If the relief valve fails or is set to an improper pressure, the pump will continue to pressurize the system until the weakest component gives, thereby relieving overpressure.

The distance between the booster pump/pressure relief/regulator outlet and dynamometer load control valve should be minimized. This ensures that the pressure and volume delivered to the dynamometer is not affected by the head-loss associated with the distance traveled through a piping system. If your pump fails to provide the minimum required supply pressure and volume the dynamometer is designed to operate with, you’ll effectively decrease the absorption capacity of the brake unit and therefore the maximum power.

Water Pressure Regulator/Relief Valve: The water delivery pressure requirement varies depending on the model/series of dynamometer selected. The output pressure of a centrifugal pump is fairly steady by design, but the pressure must be regulated to a level consistent with the power absorption profile of your dynamometer. Water brake dynamometers have water pressure and volumetric flow rate specifications that coincide with the unit’s optimal performance characteristic. Water brake dynamometer optimal performance occurs when all conditions are met to achieve linear control throughout the unit’s power absorption range. A water pressure regulator/relief valve, when paired with a sufficient booster pump, ensures the proper water delivery criterion is met. All water requirements noted on our product data sheets denote the pressure and volumetric flow rate required at the inlet to the load control valve to achieve the dynamometer’s optimal performance. The water pressure regulator/relief valve should be mounted at the outlet of the pump in line with the load control valve.

Load Control Valve: The amount of water to and from the dynamometer is controlled by throttling a valve in the inlet and/or outlet to achieve and hold torque values at a specific rpm or control the engine’s output progression. Manually operated globe valves, ball valves, and needle valves are all good for controlling a water brake dynamometer’s varying volumetric flow rate of water. Valves used in automatic load control systems are often teardrop valves, spool valves, or stepper-motor-operated butterfly valves.

CAUTION: GATE VALVES ARE NOT DESIGNED TO THROTTLE WATER. The design of a gate valve is for isolation only. Attempting to control loading of a water brake dynamometer with a gate valve will result in a turbulent, non-linear control profile of the dynamometer. All load control valves should be located as close to the dynamometer as possible without sacrificing personnel safety. For additional information, contact your Go-Power Systems sales engineer for details.

Plumbing: The routing of your plumbing is as crucial as the equipment you purchase to support the dynamometer test cell. It is always important to minimize joints and bends in the supply line to your dynamometer inlet. The supply pump should not be mounted in a position where it has to draw water upward from its supply tank. If an underground tank or the supply tank is located in a different area than the dynamometer, minimize the distance from the supply source to the pump inlet. If the supply tank is located outside of the dynamometer test cell, you may need an additional booster pump to satisfy the inlet pressure and volumetric flow rate requirements of your dynamometer.

If a 90-degree bend must be made, be sure to install at least one foot of straight pipe/hose prior to any system component. This allows the turbulent flow created by the rapid fluid direction change to dissipate while traveling through the bend. Use flexible, non-collapsible hose to make otherwise sharp bends more gradual and limit the pressure drop normally experienced when using threaded or copper plumbing fittings. PVC, CVPC, or PEX can be used and have lower head-loss characteristics than carbon steel pipe. However, temperature must be monitored to ensure the deformation/melting point of the material is not exceeded.

Portable dynamometers are units that can be configured for installation in virtually any application because of their small footprint and ease of installation. All Go Power Systems water brake dynamometer models are considered portable. By design, they can be directly mounted to a diesel engine flywheel housing or automotive bell housing. In this close-coupled configuration, they require no additional support or equipment to perform load testing on an engine or prime mover. The dynamometer absorbs the torque absorbed at the flywheel and transfers it directly back to the engine block. Therefore, it is not required to bolt the engine to a fixed base. We have many engine carts and pallets for engine support and transport available for a wide variety of testing applications. Go Power Systems has over 50+ years of experience manufacturing portable testing solutions and has designed numerous adaptation methods for engines with non-standard output shafts using various drives and gearboxes.

Our portable dynamometers can also be used in driveshaft applications. We manufacture many dynamometer stands to suit practically any test setup. When a chassis dynamometer is not practical or available, the DT-series dynamometers can be fitted with our IFA-D2000 in-frame adapter. This device can be mounted within the driveline of heavy-duty trucks for in-vehicle engine testing. An additional advantage to owning a portable dynamometer is that when your engine testing is completed, the dynamometer can easily be disconnected and stored until it is required again for service. Go Power Systems portable dynamometers are truly the ultimate bolt and go: solution to all of your testing needs.

It is important to understand that horsepower is basically a calculation that reflects the relationship between torque and rpm throughout the operating range of engines or other prime movers. When determining what dynamometer will support your test criteria, you need to know the peak torque and at what rpm it develops for each engine you’ll be testing. This data can usually be obtained from the engine manufacturer. After determining those parameters, draw up a test profile that contains what power and torque you want to hold or achieve and at what rpm ranges you expect to see those values. From there, plot out your profile test points on an hp/kW and torque/N-m vs. rpm graph, also known as a duty curve.

Each dynamometer series and model has a different absorption characteristic and therefore a different duty curve associated with its capabilities. If you have a small engine or electric motor, our D-100 dynamometer model is probably best suited for you. Most automotive applications, smaller diesel engines, or other higher rpm prime movers will fit into one of the three models in our 57-series dynamometers.

Heavy diesel engines, piston aircraft, and other high torque/low rpm applications will fit the DT dynamometer series. Go Power Systems sales engineers can help you determine which dynamometer best fits your testing requirements.

Routine maintenance includes greasing bearings, changing the shaft bearing oil (DT series dynamometers), dead-weight calibration of the load cell to the device where it’s measured, and so on. Often, these items can be overlooked. However, with a proper maintenance routine, your Go Power Systems dynamometer is capable of providing many of years of service.
Routine maintenance includes greasing bearings, changing the shaft bearing oil (DT series dynamometers), dead-weight calibration of the load cell to the device where it’s measured, and so on. Often, these items can be overlooked. However, with a proper maintenance routine, your Go Power Systems dynamometer is capable of providing many of years of service.

Dyno Model-Specific FAQs

The DY dynamometer series was the first Go Power Systems dynamometers manufactured. It was replaced by the D-100 model small-engine dynamometer. Though many DY series dynamometers are still being used today for testing, Go Power Systems no longer manufactures spare parts for these models. However, if a problem exists with the load cell assembly, you can purchase a current hydraulic load cell assembly and retrofit it to your brake or retrofit an electronic strain gauge assembly to the torque arm. Ask your sales engineer for details.
In some instances, yes. Most of these units are serviceable by Go Power Systems, and many parts are still manufactured for the support of these models. Some parts on earlier models cannot be replaced, such as the shaft/rotor assembly or stators because they have not been in production for many years. Evaluating the internal wear will dictate if your brake can be serviced. To obtain assistance, first accurately identify your model. The D-300/500 and 302/502 is easily identified by its input shaft that is directly splined for a clutch disc interface method. This model does not have a removable input shaft; rather, the shaft rotor assembly itself has a splined interfacing end. Many of these models were manufactured with a GM or VW matching splined shaft.

The D-312/512 can be identified by checking the connection method of the removable hub adapter at the input end. If you purchased the dynamometer and it came with a mounted, splined input shaft adapter, removed the mounting bolts and look at the end of the shaft/input shaft hub assembly. If the main shaft has short male splines and the shaft hub assembly has corresponding female splines and a C-clip retainer, it is a model D-312/512. The D-316/516 is virtually the same as the D-312/512, but has a smooth bore hub adapter keyed onto the main shaft.

All of the above models are single-trunnion units with alloyed aluminum construction and some spare parts are still in production. If you have any questions, your Go Power Systems Sales Representative will be happy to assist you.

Yes. Contact Go Power Systems for the latest installation, operation, service, and repair manuals for all of our equipment.
The D-100 utilizes a flexible coupling, most commonly a Love-Joy: or equivalent flexible coupling to attenuate vibrations associated with engine output that would otherwise migrate into the dynamometer and cause damage. Go Power Systems can supply an interface coupling if the customer specifies the engine output shaft dimensional data. However, due to the variety of couplings used and engines that can be tested using the D-100 model, there is no standard coupling utilized for all applications.

A driveshaft can be used for setups that require additional clearance; However, if using this method of testing, Go Power Systems recommends supporting the driveshaft with bearings after alignment. Also, the driveshaft must be torsionally compliant and, for safety purposes, must have a driveshaft guard.

Unfortunately, without taking the dynamometer apart, there isn’t a concrete way to tell what condition the dynamometer is in. One method is to use a flexible borescope to look inside at the wear on the shaft rotor assembly and stators. Heavy pitting at the inlet/outlet fitting bosses indicates cavitation has occurred or the brake unit has seen a lot of action over the years. Keep in mind that Go Power Systems has supplied dynamometers to the industry for over 50 years. Most of our units are still being used today due to one fact—they’re built to last.

If you are considering purchasing a used dynamometer and don’t have a chance to inspect it before buying, you can check several items after it is in your possession. Try to rotate the shaft/rotor assembly by hand. It should have a reasonable amount of resistance due to the spring pressure of the mechanical seals working against you, but it should rotate somewhat freely.

Next, turn the unit upside down (with the inlet/outlet fittings pointing up) and support it in this position. Grease all bearing fittings, flushing the old grease out until it is expelled from the bearing races. Fill the absorption module with antifreeze or ethylene glycol and let it set for about an hour. If dry, the seals will expand and the internals will have a nice lubricating coating. Try to slowly rotate the shaft/rotator assembly several times in both directions (remember that all Go Power Systems portable dynamometers, with the exception of the DT-3000, are bi-directional units). Repeat this step several times over the course of a day. If the dynamometer still does not free up at this point, it may be in need of an overhaul kit. Contact Go Power Systems for more information.

CAUTION: You must dispose of the antifreeze or ethylene glycol fluid in a manner consistent with your local environmental protection requirements. This includes flushing the dynamometer several times with clean water to remove residual antifreeze. Do not dispose water containing antifreeze or ethylene glycol into a city sewer system or on the ground. This can lead to ground water contamination.

Ask these fundamental questions:

  • How many runs has it performed and for how many hours?
  • When is the last time this dynamometer was loaded on an engine run?
  • Are you the original owner? If not, is the person you obtained it from the original owner?
  • Has this dynamometer been overhauled? If yes, what work was done and What was replaced? Was the work performed by Go Power Systems?
  • Did the dynamometer have any problems prior to removing it from service? Is it in need of an overhaul?
  • Does the dynamometer leak from anywhere?.
Depending on the model, a strain gauge upgrade may be available; however, the unit must be sent to our factory for the upgrade because of modifications our engineers must make. Contact Go Power Systems for pricing.
To interface a hydraulic system to a digital device such as a Go Power Systems DC-200 console or a GPS-2508/5000 data acquisition system, a torque transducer assembly must be used. This assembly allows the operator to bleed air from the hydraulic system and interface directly with our torque harnesses. The torque transducer assembly converts the hydraulic pressure to a proportional electronic signal (1- to 6-volt DC or in certain applications 0–30mv) which then transmits to the torque input channel and displays as a torque reading. Go Power Systems has interface kits for every dynamometer model we manufacture that utilizes a hydraulic load cell system.

The only hydraulic fluid Go Power Systems recommends is Dow Corning 200 silicone fluid. Any other fluid, such as ATF, may contain detergents that chemically attack the diaphragms and cause leaks or premature failure. Load cell diaphragms are available through Go Power Systems; we also manufacture a load cell refill kit for recharging the fluid system. For ease with the bleeding procedure, make sure your dynamometer is equipped with bleed screw assemblies at the top of each load cell Canister. If you have an older model and have no way to bleed and recharge the system, Go Power Systems also manufactures a torque line assembly upgrade with the correct fittings for purging air and refilling your hydraulic load cell system.

CAUTION: You must take care when replacing load cell diaphragms. To avoid tears or improper installation, contact Go Power Systems or refer to the Service section of your owner’s manual. If your diaphragms have failed, the most likely cause is age, improper fluid, or improper installation.

Yes. The DC-200 has replaced this console with a digital display for remote testing away from the dynamometer through 30-ft. torque and tachometer harnesses. A data acquisition system is also a great upgrade for these older consoles. However, the DA-300/500, 302/502 models have parts that require conversion components to interface them with electronic controls and/or data acquisition systems. Call Go Power Systems for more details.
Many of the above mentioned consoles cannot be serviced or repaired because parts are no longer available or manufactured. The DC-200 digital console is the current replacement for all of those Go Power Systems console models. We also manufacture turnkey data acquisition systems built to your specific testing requirements.