German Auto Solutions Dyno Services

 German Auto Solutions is in the final stages of the installation of our automotive in ground chassis dynamometer. The German Auto Solutions staff already has 15 years experience with dyno testing and tuning through our sister company FastBikes-USA. The automotive dyno will use the same Superflow data acquisition and control system as the current motorcycle chassis dyno. We will post pictures and dyno graphs once the installation is complete.

 Our Superflow chassis dyno is not just capable of measuring and plotting horsepower and torque, but also has a vast array of configurable digital and analog inputs for measuring data such as oil pressure, oil temp, exhaust temp, turbo boost, fuel and air consumption or any other parameter that can be measured via digital or analog inputs.

 The dyno automatically corrects all measured data to SAE standard sea level conditions based on atmospheric conditions, including air temp, barometric pressure, humidity and vapor pressure. The software doesn't just apply this data to the atmospheric horsepower calculations but even goes so far as to use the calculated air density to adjust the air drag losses of the dyno roll rotating through the air, applying plus or minus hundredths of a horsepower corrections for air drag on the roll to the already sophisticated SAE atmospheric correction.

 All this adds up to a truly astounding level of repeatability. We have proven that we can dyno test a vehicle on one day, then retest that same vehicle, days, weeks and sometimes even years later, under totally different weather conditions and receive exactly the same results. In fact the horsepower plots will virtually lay on top of each other if there have been no changes to the engine or drive train between tests. This gives us confidence that changes that show up on a dyno pull on a different day are valid and useful for diagnosing a loss in power or quantifying a gain made from modifications since the last dyno test day.

  Complementing our Superflow dyno is a four gas digital Exhaust Gas Analyzer (EGA) and a Wide Band O2 sensor which reads and plots in real time. We rely on both 4 gas EGA and O2 for all mapping procedures. Most dyno tuning centers rely solely on wide band 02 because of its ultra fast response time but do not realize that O2 readings can be erroneous at some combinations of throttle position and RPM, especially in situations with long duration performance camshafts.

Dynamometer Terminology

Chassis Dynamometer - A device for measuring horsepower produced by an engine by simultaneously measuring torque and rotational speed (rpm). A chassis dynamometer measures power at the wheel of the vehicle eliminating the need to remove the engine from the chassis of the vehicle.

Engine Dynamometer- A device for measuring horsepower produced by an engine by simultaneously measuring torque and rotational speed (rpm). An engine dynamometer measures power at the crankshaft of the engine which requires that the engine be removed from the vehicle and mounted to a test fixture. The test fixture provides a rigid structure to restrain the engine during testing plus all electrical, fuel and ignitions requirements to operate the engine.

Dyno Roll - The large roll or rolls on a chassis dyno. The vehicle engine transfers power through the drive train, to the wheels, and then through the tires to the dyno roll. The dynamometer uses the inertial mass of the dyno roll and the rate of acceleration to calculate horsepower and torque.

Eddy Current Brake - A computer controlled electromagnetic braking system that allows the dynamometer to control the rate of acceleration or deceleration of the vehicle during testing. An Eddy Current Brake can also be used to hold an engine at a steady rpm regardless of throttle setting. Although they are essential for carburetor tuning and fuel injection mapping not all dynamometers are equipped with Eddy Current Brakes.

Acceleration Test - A simple dynamometer test in which the vehicle is accelerated from a low rpm to a high rpm (typically redline) at a fixed throttle position (typically wide open). The dynamometer uses the inertial mass of the dyno roll and the rate of acceleration to calculate horsepower. This is the quickest and simplest dyno test for measuring horsepower.

Controlled Acceleration Test - A dynamometer test in which the vehicle is accelerated from a low rpm to a high rpm (typically redline) at a fixed throttle position (typically wide open). During this test the dynamometer uses a computer controlled Eddy Current Brake to control the rate of acceleration during the test. The dynamometer uses the inertial mass of the dyno roll and the rate of acceleration to calculate the inertial component of the horsepower measurement, and then adds the power dissipated by the Eddy Current Brake during the test to calculate the total horsepower. This test is useful for testing high horsepower vehicles which would otherwise accelerate to quickly during an "Inertia Acceleration Test" to properly load the engine.

Controlled RPM Test - A dynamometer test where the vehicles engine speed is held at a constant rpm by a computer controlled Eddy Current Brake. The dynamometer operator sets the engine speed via the dynamometers controller. He is then able to test the vehicle at any throttle position while the dyno constantly varies the load applied to the dyno roll via the Eddy Current Brake to maintain a constant rpm. This type of test is essential for fuel injection mapping. Through the use of an Exhaust Gas Analyzer to monitor fuel mixture in real time during this test, the dynamometer operator can check (and adjust if necessary) every aspect of the fuel delivery map.

Step Test - A dynamometer test in which the vehicle is accelerated from a low rpm to a high rpm (typically redline) at a fixed throttle position. The dynamometer uses a computer controlled Eddy Current Brake to control acceleration in fixed rpm increments (steps). The dynamometer holds the rpm steady at each step for a fixed period of time before advancing to the next step. Both the rpm step increment and the step hold time are predetermined by the operator and entered into the dynamometers controller before the start of the test. A typical example would be an rpm increment of 1000rpm per step and a hold period of 5 seconds per step. Step testing is useful in conjunction with an Exhaust Gas Analyzer for testing air/fuel mixture since the pauses at each step allow the analyzer time to record a stable reading. Step tests also result in more accurate hp and torque measurements to due to increased loading of the engine and the elimination of engine and drive train inertial losses.

Air Drag Coefficient Test - A dynamometer test in which a computer controlled load is applied to the dyno roll via an Eddy Current Brake. The amount of load applied is calculated and constantly updated by the dyno's computer, based on roll speed (mph) and the air drag coefficient of the vehicle. The dynamometer operator enters a value in square feet equal to the frontal area of the vehicle prior to the start of test (usually a rough approximation). This test actually simulates driving a vehicle on the open road. As the vehicle is accelerated through the gears the dyno calculates what the actual air resistance would be based on speed, and applies that amount of breaking force to the rear wheel through the dyno roll. If the vehicle is accelerated through all gears it will eventually encounter enough braking force (simulated air drag) to reach a top speed. This maximum speed would be equal to the top speed achievable by the vehicle on the open road. This test has many applications such as new engine break in, diagnosing drivability or intermittent problems and in conjunction with an exhaust gas analyzer, tuning carburetors. Air drag is a velocity squared equation, meaning that it takes four times the horsepower to double the top speed. If a vehicle develops 200hp and reaches a top speed of 130mph, the same vehicle would need 800hp to reach 260mph.

Air/Fuel Ratio - The amount of air relative to the amount of fuel in the air/fuel mixture expressed as a ratio. Measured by mass (weight) not volume.

Dyno Test - To use a dynamometer to measure parameters such as horsepower, torque, fuel mixture, etc. Never tell a shop you want your car dyno'ed, always use the terms "dyno tested" or "dyno tuned". Dyno Tune - To use a dynamometer to adjust engine parameters to achieve maximum performance. Typical parameters include fuel mixture (carburetor jetting of fuel injection mapping), ignition timing, cam timing, and intake and exhaust modifications. Never tell a shop you want your car dyno'ed, always use the terms "dyno tested" or "dyno tuned".

ECU - Engine Control Unit. A computer controlled device which monitors and controls all electrical functions of an engine. Typical functions which an ECU controls include ignition timing and firing, fuel injector pulse width control and firing, cold start enrichment, idle speed, rev limiter, etc. Typical parameters which an ECU monitors include, engine rpm, crankshaft and cam shaft position, engine temperature, air inlet temperature, exhaust oxygen sensors, barometric pressure, etc.

EGA - Exhaust Gas Analyzer. A device which samples the exhaust gasses produced by the vehicle engine to determine the percentage levels of individual gasses in the exhaust stream. For high performance engine tuning the gasses of interest are O2, CO,CO2 and HC.

Fuel Injector - A device located in the intake tract of a fuel injected engine. A fuel injector is basically an electronic "on/off" valve for fuel. Pressurized fuel is plumbed to the injector inlet and the injector is cycled on for a short period of time during each engine intake cycle. The length of time the injector is held open is called the "injector pulse width" and determines the amount of fuel allowed to pass into the intake air stream. The injector sprays a very fine pattern of fuel to help ensure that the fuel is uniformly mixed with the incoming air. The injector is controlled by the ECU.

HP - Horsepower. A measure of work performed. When applied to an engine the formula is (Torque x rpm)/5252.

Injector Pulse Width - The length of time a fuel injector is held open per intake cycle expressed in milliseconds (ms). Injector pulse width is controlled by the ECU to ensure the proper amount of fuel is delivered during each engine intake cycle typically based on throttle position and rpm.

Lambda - Lambda is the measure of an air/fuel mixture as referenced to stoichiometric. A Lambda value of 1.0 equals stoichiometric (14.7/1 for gasoline engines), lambda values less than 1.0 represent rich mixtures, lambda values greater than 1.0 represent lean mixtures.

Lean Mixture - An air/fuel mixture that has too much air compared to the amount of fuel in the mixture, a lambda measurement greater than 1.0, an air fuel ratio greater than 14.7/1 for gasoline engines.

MAP - A table stored in the ECU (Engine Control Unit) of a fuel injected vehicle. The table contains the data necessary for the ECU to determine the proper amount of fuel to deliver to the engine at any specific rpm and engine load.

O2 Sensor - Oxygen Sensor, also called a Lambda Sensor. A sensor located in the exhaust stream of the engine to determine the amount of residual oxygen remaining in the engine exhaust.

Rich Mixture - An air/fuel mixture that has too much fuel compared to the amount of air in the mixture, a lambda measurement less than 1.0, an air fuel ratio less than 14.7/1 for gasoline engines.

RPM - Revolutions per Minute. A measure of rotational speed.

Stoichiometric - An ideal air/fuel mixture that contains exactly enough oxygen to completely burn all the fuel in the mixture. A stoichiometric mixture theoretically leaves no residual fuel or oxygen in the exhaust after combustion. An air fuel ratio of 14.7/1 for gasoline engines.

Throttle Position - The amount of rotation of the throttle plate expressed in percentage from 0-100%.

Torque - A measure of rotational force expressed as force times distance. Example - imagine a 1 foot long lever, welded to and perpendicular to a drive shaft. 1 pound of force applied to end of the 1 foot lever would result in 1 ft-lb of rotational force at the end of the drive shaft. 2 lbs applied to a 1 foot lever, or 1 lb applied to a 2 foot lever would both yield 2 ft-lbs of force. Torque combined with speed (rpm) is used to calculate horsepower (hp).

CO - Carbon Monoxide, an exhaust gas useful in dyno tuning for determining Air/Fuel Ratio.

CO2 - Carbon Dioxide, an exhaust gas useful in dyno tuning for determining combustion efficiency and optimum ignition timing.

HC - Hydrocarbons, exhaust gases useful in dyno tuning for determining combustion efficiency and detecting misfires.

O2 - The natural state of oxygen in the atmosphere, two oxygen atoms bonded as an O2 molecule, useful in dyno tuning for determining air/fuel ratio.