The Results are In

Dec 2, 2009

When your speed shop offers quality dynamometer testing to your hardcore racing customers, it does more than set your company apart from the discount auto parts store down the street. It literally drives business to your door.

“If properly displayed and promoted, a professional dynamometer and the credibility it provides the speed shop allows for selling more product, charging more per-hour and attracting more upscale drivers,” says Bob Bergeron, president of Land & Sea DYNOmite Dynamometer. “It is truly an investment and insurance policy for the long-term success of any speed shop.”

It follows this basic business premise: The more information you have to give your customers, the easier it will be to sell your products.

“When deficiencies are uncovered during dynamometer testing (in power output, fuel efficiency, emissions, drivability, etc.) the technician can suggest solutions,” Bergeron continues. “Selling upgrades or additional services, proven on the dyno, is always easier. No driver wants to leave power or economy on the table, and the extra cost of dyno time is trivial compared to how much money they have invested in the engine. Drivers should be made aware that dyno-tuning their completed engine, with all of its individually purchased components working together, is the only way to realize those pieces’ full potential.”

Nelson Lee of Dynojet agrees.

“The biggest benefit to speed shop owners offering dyno testing it that it drives more business through the door by cross-selling dyno tests with tuning and performance part sales,” he says. “From a sheer technical standpoint, it’s all about capturing useful data. When armed with quality data from dyno testing, then assessing whether or not those new speed parts made a positive gain (or loss, I suppose) is very easy. This data is also crucial when creating a custom tune for late-model EFI vehicles. You can’t just take a stab in the dark and expect more power at the tires-it’s just not going to be the safe thing to do in the long run.”

Understanding the Results

Dynamometers are used to test all aspects of an engine’s overall performance.

“Most dynos test for horsepower and torque,” says Allison Blackstein, director of sales and marketing for Dynocom. “Our dyno also can in real-time plot distance, acceleration, speed, engine rpm, air/fuel, timing, OBDII channels, analog input channels (boost, temperature, etc.), derived formula channels (formula based on the sum, difference or mathematical equation of other channels) as well as others.”

But after the engine or the car gets off the dyno, the work really begins.

“Shops should explain what they will be looking for even before testing begins,” Bergeron explains of dyno results. “After the runs, the data analysis session should last longer than the testing session itself. The focus is never simply on power peaks, but rather on what the shapes of the curves and related channels are trying to tell you. Follow-up calls can be used to tie the data (once the customer has had time to digest it all) to modification plans to improve performance. By keeping the data at the center of discussions, you really pull the customer into the master plan you outline.”

Lee suggests the shops that run his dynos take the results to another level.

“We encourage our dyno centers to put the dyno run data files on a USB thumb drive (memory stick) for their customers. Our WinPEP 7 software is posted on our Web site, and is free to download. The dyno test results can then been easily viewed with the full flexibility that the dyno owner enjoys.

Many of our shop owners have found that comparing the current dyno run with other dyno runs of the same engine type and size can be a valuable tool in helping to sell your customers additional performance products,” he continues. “You can show how a different set of headers, or cam, or perhaps a bit of nitrous might increase their power output. Having graphical data of the age-old parable, ‘Speed costs, how fast do you want to go?’ is a great sales tool.”

The information can get quite technical, Blackstein explains.

“Our company’s software can output results in printed graphs, detailed report, numerical data plots, electronic spreadsheets, email, database file, and a proprietary data file,” she says. “It is typical to give the printed report and graph. However, it is also common to give them the data file that represents all the data during the run and have the customer download a Dynocom viewer so they can open the file to see all the numbers in graph and tabular form.”

And all manufacturers interviewed for this story agreed on one thing: the details matter when doing dyno testing.

“To get the most consistent results, attention to detail is critical,” Lee says. “Too often, simple things can be overlooked, and when not paid attention to, the resulting data may be erroneous. A simple ‘pre-flight inspection’ before dyno testing can go a long way toward increasing your consistency.”

To make dyno tests comparable, he suggests checking tire pressure, fluid levels and air and fuel filters, always using the same fuel and lubricants (unless testing new fuels or fluids), monitoring engine, coolant and intake air temperatures, and using the same SAE atmospheric correction factor each time.

“Attention to these items, and a few others, will go a long way toward improving the quality of your results, if not the horsepower numbers,” he says.

Apples to Apples

The popular disclaimer “results may vary” is true when comparing dynamometer results-particularly if the tests were performed at separate facilities.

“Drivers tend to look at A/F, torque and power. These numbers tend to be big for them,” Blackstein says. “However, tuners and real engine builders will look at all the numbers to formulate a good combination of high power and longevity of the engine.”

The biggest challenge facing both shop owners and customers are car owners who question the horsepower and torque numbers from one dyno to another, says Matt Schultz of Stuska Dynamometers.

“It’s funny how the only number the customer wants to believe is the biggest they’ve seen or heard,” he says. “There are many variables involved that can affect the horsepower numbers a dyno gives: air quality, air intake system, exhaust system, the SAE correction factor being used, friction loss calculations, proper calibration, inertia factor for sweep testing and the inertia compensation calculations, to name only a few.”

And perhaps the biggest variable is the dyno operator himself.

“After all is said and done, it comes down to the honesty of the guy running the dyno,” Schultz says. “Unfortunately, you can make the numbers look however you want, and they can be very easy to manipulate. That being said, even with an honest operator, it is not uncommon to see a difference in horsepower of up to 10 percent from one dyno to another.”

The most accurate results of performance improvements come from comparing equal tests, says Blackstein.

“When using a dyno, do not compare load tests with inertia tests,” she explains. “They are two different tests, and are like comparing apples to oranges. It is important to compare tests of the same kind when doing comparisons. Also, never look at the maximum power or torque. It is better to go with the higher average numbers, but many shops just look at the maximum power to give the customer.”

Under Control

Testing control is a big issue, adds Steve Matthieson of  SuperFlow.

“The user interface, dyno accuracy, what the user sees, touches and sells to his customers is what makes a dyno valuable and worth paying for the time on the dyno,” he says. “While having the data in a graph is good information, being able to view the data in a spreadsheet form is extremely valuable, too. When you see a dip in a power curve, for example, and all you have to look at is the power/torque graph, a clue to the cause of the dip may be elsewhere, such as in airflow or timing or engine water temp. When we see a dip in power, we look first at the airflow and fuel flow numbers to make sure there is not a corresponding drop. If you see airflow and fuel flow dip at the same engine speed where the torque dipped, then you may have an intake manifold problem or a turbo boost issue. These are a few examples of the diagnostic tools that a dyno operator can sell to his customers.”

The biggest error shops make, according to Matthieson, is to not have enough airflow in their dyno test area.

“Adequate airflow is especially important when using a chassis dyno,” he says. “We provide a very complete software tool that will calculate the airflow requirements for a given range of cars and power levels. Most people tend to ignore the amount of air needed and end up chasing air/fuel ratios and poor repeatability of the tests simply because the ECM is backing out timing or injector dwell due to elevated under-hood temps. In engine dyno test cells we recommend at least 14,000 cfm, which requires a 5- to 7-hp tubeaxial fan. The same fan would work well for most chassis dynamometer testing, but few people are willing to spend the amount of money to properly control the test environment.”

What They Get

Beyond the technical data, shops will want to fully market the value of a dyno test to customers beforehand, Stuska’s Shultz believes.

“Besides the numbers you get, there is a whole other side to getting the most out of your dyno. This is from a marketing perspective. Many shops fail to market their dyno, and the benefits of having one, to their full potential.”

One main benefit, he says, is quality control.

“Not only are you verifying the performance of the engine,but you can also checkfor leaks and resolve fine-tuning issues or potential problems before the customer receives the engine,” he says. “A dyno builds customer confidence in your workmanship. Use the dyno as a showpiece and attention-grabber for your shop. Have an open house in the off-season and run an engine for potential customers. When they hear the engine and smell the burned race fuel, they will get motivated to buy. Dyno every engine,whether it’snewor arebuild, and have the fee built into the package price. In the long run, this will make you more money, increase quality and customer satisfaction.”

 SuperFlow’s Matthiesen breaks it down into a pair of core user groups.

“There are two groups of users who rely on one or the other for their testing needs. Obviously what one group needs (engine dyno) with regards to information is not what the other group (chassis dyno) needs. In the case of the chassis dyno, we see a lot of users looking at peak horsepower numbers and peak torque numbers more or less bragging rights. But it is the area under the curve that is the most important and will best relate to the performance of the car.”

All the technical information can be boiled down into one specific sales point for your customers.

“It has been stated that one day on the dyno is worth five days on the track,” he says. “If you race NASCAR, renting a track for a day is very expensive, so what you want to have is all the preparation of the engine out of the way and it tuned as well as it can be before you take it to the track. We have many teams that use both the engine dyno and a chassis dyno for their testing and then when they have the chassis and the engine tuned together they go the track.”

Mainly, Blackstein says, shop owners can use the dyno results as a way to suggest customers invest in further performance enhancements.

“It is not the numbers that are important, but the change in numbers from when modifications are done,” she says. When a shop is working with a customer who is ready to invest in performance, “it’s easier to test a vehicle in-house and quickly perform modifications and re-test. After all, it is a little difficult doing full throttle testing in traffic for long periods of time—not to mention the non-legal aspects.”