“Dyno Tech Talk” web pages

A new technical article section has been added to the Land & Sea web site. Reach it from the www.land-and-sea.com home page by selecting “Dynamometer” on the main menu, and then clicking on “Dyno Tech Talk”. Some of the covered topics include:

• Corrected Horsepower -Correcting dynamometer hp to SAE, DIN, or other atmospheric condition standards.

• Dampening Data -When to average, dampen, or otherwise filter the display of dynamometer test data.

• Determining Inertia -Using DYNO-MAX 2000 and your dyno to self-calculate the engine's polar-moment-of-inertia.

• Dyno Hp Limits -What limits the maximum power you can accurately read from a roller chassis dyno?

• DYNO-MAX "Hot Keys" -Special PC accelerator function keyboard shortcuts speed dynamometer testing.

• EGT Response Time -Attaining quicker reaction times from EGT thermocouples via DYNO-MAX 2000.

• How Dynos Work -Reprint from Kart Racer magazine on the basics of dynamometer operation.

• Inertia Compensation -Using Channel Dampening in conjunction with Inertia Compensation.

• Inertial vs. Steady State Hp -See why your dynamometer shows an engine's inertial and steady state Hp will not always match.

• Parasitic Losses -Step-by-step instructions on determining driveline parasitic loss values for any chassis dynamometer.

• PID Tuning -Tips on tuning a dynamometer's electronic load control Gain, Drift, and Rate (PID) settings.

• Race Simulation -Requirements for performing high power race track simulations on a chassis dynamometer.

• RFI Troubleshooting -Reducing problems with ignition systems interfering with sensitive data acquisition systems.

• Recalibration -Why, when, and how to perform recalibration of the dynamometer's torque readings.

• Repeatability -Suggestion for improving the repeatability of any dynamometer installation or test session.

• Smart Ratio -Automatically enters the correct DYNO-MAX overall gear ratio for simplified chassis dyno setup.

• Sweep Rate -Tips on selecting the optimum test sweep rate for evaluating real world performance on the dyno.

• Tire Damage -Goodyear Tire's interesting comments on tire safety and chassis dynamometer roll diameters.

• Tire Slippage -Tips on improving traction on older chassis dynamometer rolls.

• Torque Hysteresis -Reducing the water brake's plumbing hose loads to improve the dyno's repeatability.

• Using BSFC #'s -Utilizing the Brake Specific Fuel Consumption data to help tune the engine.

• Water Supply Tanks -Basics of selecting water supply tanks for engine or chassis dynamometers.

“How can I verify my flow transducer's calibration?”

While the default calibration values for each model of DYNOmite flow transducer provide reasonable accuracy, flow testing your individual unit insures maximum precision.

Frequency based turbine style flow transducers use a Flow Factor (gain multiplier) to scale their raw channel output frequency (whether in RPM or Hertz) into a high level final flow reading. Most liquid transducers are fairly linear (except when used above or below their recommended flow ranges). Note: Non-linear models require an exponential multiplier and/or an Edit Correction Table.

If you have an accurate electronic transducer, mechanical (sight glass style) flow meter, or test flow bench you can use it (in series with your device) to adjust DYNO-MAX's Flow Factor (until both devices’ readings match). If you do not have access to such calibration equipment, your transducer can be calibrated with a simple volume (or weight) vs. time flow test -as follows:

WARNING: To prevent fire or explosion, do not perform the following test using gasoline (or other fuels) without appropriate safety precautions.

1) Disconnect the fuel line (after your flow transducer) from the fuel rail or carburetor. Route that output to spare catch pail #1.

2) Turn on the fuel pump and wait for the pressure to stabilize and all bubbles to clear.

3) Quickly switch the hose to a 2nd (clean and dry) sample pail #2 while you simultaneously press DYNO-MAX's Record button to capture fuel flow data. Note: Do not use “A -B” for this test, you just want what is running thought the single “A” transducer alone. Also, if the flow is not steady, you may need to add a discharge restriction orifice to raise the fuel system’s testing pressure slightly.

4) After approximately 60 seconds, quickly switch the hose back to pail #1 and simultaneously press Pause to end the recording.

5) Measure the volume (or weight if you have an accurate grams scale) of fuel that was flowed -and also note the duration of the recording. Note: If you are comparing results by weight, you must also enter the fuel's correct specific gravity into DYNO-MAX.

6) Graph the results and compare your average bucket test measurement's flow rate with the average graph data points flow.

7) Adjust DYNO-MAX's flow factor up or down (as required) by the percentage of error. Tip: Repeat the test for verification -if results vary, or require large adjustments to the transducer's default Calibration Flow Factor, you are doing something wrong!

Example: If in 60 seconds the test flows 2 pounds of fuel, that equals 120 pounds per hour. If DYNO-MAX’s Fuel PPH data was hovering at 117 pounds per hour during the test, you would need to adjust its channel calibration gain (flow factor) by 2.5%.

Tip: A DYNOmite-Basic board's “Final Reading” is in Pounds per Hour (so the Specific Gravity must also be correctly pre-set before recalibration). However, DYNOmite-Pro board's “Final Reading” is in Gallons per Hour.

Powertech Dyno Service

...located in St Johns Michigan, specializes in high performance snowmobile engine testing and research. Carl Galloway, the company’s founder and a former General Motors manufacturing engineer, has been a snowmobile enthusiast since the early 70s. After a long automotive career, he decided to retire and pursue his interests in performance snowmobile engine research.

In 1999, after years of trail riding and tinkering, Carl decided to open a test facility focused around a dedicated snowmobile dynamometer. He knew he wanted to be able to test engines (accurately) either with them in or out of the chassis, plus handle the power of today's biggest drag race and hill climb engines. Carl's research revealed that a DYNO-MAX equipped DYNOmite system was the only professional sled dyno solution.

After taking delivery of a fully equipped DYNOmite 13" absorber and data accusation system, Carl took over custom fabrication of the unique (in or out of chassis) docking station below. Today, Powertech boasts one of the most versatile snowmobile dynamometer test facilities around. Consequently, Carl has become one of the Midwest's premier high performance snowmobile dynamometer experts and Powertech the dyno shop of choice for many of the region’s top drag race, lake race, snow cross and oval competitors. In fact, Carl regularly tests large drag race engines that exceed 300 hp!

Carl considers the shop a hobby (being officially retired), but notes that this “hobby” consumes almost all of his free time. Carl also is quick to point out that “...without the right piece of equipment, this would not have been possible. The accuracy, repeatability, and ease of use of the DYNOmite is one of the keys to my success.” Carl's paid us back though! Some of his own insights are part of DYNO-MAX 2000 today -back in 2000 he was one of the beta testers for this state-of-the-art software.

PO Box 96 North Salem, NH 03073