The time is fast approaching when pc-based software will become commonplace in the selection, matching and evaluation of engine components. Software systems for suspension adjustment and on-track performance analysis are also evolving. Take note, because these programs can save both time and money.
Like it or not, our reliance upon personal computers is growing by megabytes. While the hard-core racer or engine builder may, so far, have overlooked the benefits of including the family PC in his racing activities, times are changing. Winning teams and engine builders who have cultivated an interest in “electronic performance evaluations” are rapidly discovering the benefits.
Initial Thoughts Perhaps one of the most complex aspects of engine building is the selection of properly matched parts for specific racing conditions. Access to engine and chassis dynamometers merely shortcuts the process by providing power evaluations of packages that are already assembled. Evaluating engine parts packages electronically can, in fact, save money by eliminating mistakes before you purchase the parts.
Today, virtually any strategy which reduces the cost of racing is worthwhile, particularly if the process paves a clearer path to optimizing engine power and on-track performance. That “balance” may take the form of well-written, user-friendly PC-based software packages that are becoming increasingly comprehensive and cost-effective. And, given the fact that personal computers are an occupational benefit to everyday life, it is no surprise they’re becoming commonplace in the world of racing.
The fact is manufacturers in the passenger automobile industry have used such software packages for years—although they are normally much more complex and expensive. For example, engines can be designed and “run” on computers before any tangible prototype pieces are even built. While the cost of such software may be high, it isn’t nearly as expensive as beginning the manufacturing process with a flawed design.
Today, if you had access behind the closed doors of leading Winston Cup engine shops, you’d see an array of PCs and sub-mainframes stuffed with software that does everything from model engine components to dynamically dissect material stresses, aerodynamic loads, and fluid flow...all on a computer screen. “Cut and try,” it ain’t. And when you load the picture with decades of hands-on experience and blend it with state-of-the-art engineering expertise, woven with in-depth computer software and processing speed, what do you get? A championship race team.
What are the cost-to-benefits of PC-based software for the Saturday- night racer? We posed this question to four software developers and an engine builder. Consensus opinion showed that racers need to optimize their parts investment by reducing selection errors. If time can also be saved in the process, so much the better.
“You’re trying to optimize resources (money and time) by investing in items that appear to have the highest probability for success. It makes no difference what the size of your operation. This is a universal problem,” Curt Leaverton of Dynomation says.
John Block of Auto-Ware, a provider of multiple types of performance evaluation software, says, “Racers should think of software in the same way they think about hand or power tools. Once you do a job with the ‘right’ tool, you wonder how you got by before.”
Kevin Gertgen of Performance Trends breaks down the benefits into three categories.
“Some programs save time, some save time and money, and others make the racer think and help in the learning process,” Gertgen says. “In any case, the underlying intent of these packages is to help abbreviate the parts selection and evaluation process, all of which can amount to a significant cost savings.” Next, we turned to Dennis Wells of Wells Racing Engines. After 25 years, Wells has logged thousands of combined hours on the flow bench, engine dyno and inertia chassis dyno. Are contemporary software packages of any value to someone like himself?
“I think they are,” Wells says. “What I first found valuable was a way to verify some of the things I’d seen over the years but wasn’t quite certain what caused the results.
“Experienced engine builders tend to rely on what they’ve learned from simply doing the work year after year. But if these same people will just step back and examine what some of these programs can tell you, it opens up new areas of thought and investigation that might not otherwise be considered.”
What skill level is required to see benefits from the use of “performance software?” Careful study of available packages indicates there are many levels of software. The wide variety offers something for racers from the beginner to professional. Those just becoming familiar with the essentials of engine building will find value in learning how various components interact with each other. In particular, the software helps establish a sense of which components may be more critical than others. For example, running comparisons of valve overlap versus total event duration can quickly establish which has the most influence on power and where in the rpm range the influence occurs.
Programs designed for professional engine builders typically provide more comprehensive results but also require more input and knowledge from the user. It is most important that you have clear-cut objectives in mind before choosing a software package to make sure it fits both your needs and resources. What are the limitations to substituting PC-based analysis to engine dynamometer or track results? Patrick Hale, owner of the software company Racing Systems Analysis, provides an interesting perspective to this question.
As an engineer/racer who earned his stripes in the aerospace industry, he says, “Initially, I was reluctant to get into internal combustion engine simulation due to the extremely unsteady behavior of the aerodynamic processes in the intake and exhaust tracks and the intermittent combustion process.
“Fortunately, motorsports people are only concerned with predicting wide-open-throttle torque and horsepower curves over an rpm range somewhere below peak torque to a little beyond peak horsepower. Therefore, engine- performance PC software does not need to be concerned with a lot of other complex ‘Detroit’ issues like emissions, noise and fuel economy. Racers are only concerned about power and being competitive. Engines that don’t make power don’t qualify or win races, so they are of no interest. As it turns out, this makes the job of the motorsports engineer and software developer much easier.
“Today, I have a high level of confidence in engine performance prediction software—certainly from the standpoint of racers or engine builders using it to cut corners and save money when they start choosing and buying parts.”
What level of accuracy can be expected from these software packages? In a discussion with Block some relevant points were raised. First, it’s worth noting that this probably is the question most often asked about performance simulation/evaluation programs.
“Not only do engine dynamometers vary from system to system, engines typically exhibit variations in output from consecutive tests,” Block says. “It’s important to understand that while engine output at any given rpm may vary, it is the trends in power represented on either an engine dyno or a simulation program that’s of value in selecting and combining parts.”
In this context, a couple of additional points are worth mentioning. First, many engine builders and racers tend to look at maximum power values. If wide-open throttle racing at a constant rpm is the objective, then perhaps an rpm-limited horsepower number is important. But race cars must accelerate; therefore, an ability to produce torque over a specific range of rpm becomes critical to on-track performance. So the shape of a torque curve within a span of rpm is often more important than maximum power. This takes us back to looking at power trends.
Through the selection of engine components, it’s possible to “shape” a torque curve into the desired pattern through a specific rpm range. For example, as we pointed out in previous articles, dimensional changes to intake and exhaust systems can affect the torque curve. Plugging assorted values for these systems into various engine software packages enables rapid and cost-effective determination of correct parts for a “proper” torque curve. And you’ll notice that we’re not focusing on specific torque values or program accuracy but only the shape of a torque curve vs. engine speed. PC-based packages have become good at this task.
The last point, relative to accuracy, is the axiom about input data vs. output data.
“The more information you can provide these programs, the more detailed the results will be,” Block says. “Plus, the more complex the program, the higher its cost tends to be. It’s best to select a program based on the level of detail desired and how much information you are willing, or able, to provide. At one end of the spectrum, a weekend racer can probably get sufficient help by purchasing a package that’s not as precise (but also less expensive) as one typically used by a professional engine builder. Additional information required by the high-end packages will result in a tighter prediction, relative to a live dyno test.”
Are the more complex software packages worthwhile? This depends how much time and money you want to invest versus the level of information required. For example, if you’re really interested in studying the dynamics of engine airflow, understanding components and how they interact is best done by pressure crank angle data. This is the basis for engine cycle analysis (ECA).
