Once you are comfortable with the formulas and concepts presented in this book, you can take advantage of more sophisticated tools that let you actually model and test your engine-building ideas on your home computer. Engine-simulation software has been around for more than 20 years, and it has steadily improved. Current programs are very robust and surprisingly affordable. Those presented here represent the cream of the crop and you can expect accurate and instructive results from all of them. We’ll take a brief look at the top engine simulators first and then a number of support programs that allow you to test your engine models on the dragstrip and at Bonneville or any of the other top speed venues such as El Mirage and shorter one-mile tracks. In the end you will undoubtedly end up purchasing some of these programs and you will thoroughly enjoy using them to test your ideas. They give you unparalleled freedom to design and test endless engine combinations while sitting around the house in your underwear and without spending a dime on dyno time.
This Tech Tip is From the Full Book, PERFORMANCE AUTOMOTIVE ENGINE MATH. For a comprehensive guide on this entire subject you can visit this link:
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Advanced computer skills are not required to operate these programs. They are all compatible with contemporary 32-bit operating systems up to and including Windows Vista and Windows 7. Most current home computers have the memory and processing speed to run them easily, although some advanced simulations may take a few minutes. If you bought your computer within the last decade you should have no trouble running these simulations. They walk you through all the steps, they provide excellent support and documentation and in some cases, online updates. For most applications, you fill in the blanks with the appropriate specs and/or choose components from extensive menus. It’s very easy and surprisingly instructive to the point that most programs will expand your knowledge and your engine planning skills just from using them.
Performance Trends (www.performancetrends.com) offers three versions: Engine Analyzer, Engine Analyzer Plus, and Engine Analyzer Pro. All of them simulate almost any engine combination you can conceive, including bore and stroke sizes from 1 to 10 inches and up to 16 cylinders with multiple valves (2 to 6) and an RPM range from 500 to 30,000.
The basic version runs simulations for gasoline and alcohol in normally aspirated mode or with turbocharged, supercharged, or nitrous options. It uses wave tuning algorithms for VE prediction and includes spark settings and detonation simulation. Supercharged applications can be modeled with and without intercooling and they include provisions for both centrifugal- and Roots-type superchargers. More than 70 engine specifications can be input to describe your proposed engine to the program. From this the simulation delivers up to 23 data outputs per RPM and 18 special calculations, such as displacement, valve flow areas, dynamic compression ratios, etc. The program estimates a cylinder head flow curve generated from a percentage-based “flow efficiency” that you choose from a table, or you can input up to three flow data points from actual flow bench data.
The program includes utility calculation screens that help you model compression ratios and other auxiliary calculations needed to support the simulator. It plots torque and horsepower per RPM graphically with up to seven overlays for run-to-run comparisons. From input or selected cam data it shows valve lift per crankshaft degree to help you evaluate cam profiles. It uses ASCII (American Standard Code for Information Interchange) text so data can be written to a file with use-defined options for importing to spreadsheets such as Microsoft Excel. An optimize feature automatically chooses best port or runner size and length and can spec for best peak torque and horsepower or average torque and horsepower. You can input any 0.050-inch-lift cam value or a specified value including advertised timing plus lift, lash, rocker ratios, centerlines, ramp ratings, and so on.
Engine Analyzer Plus The mid-level program has ten additional features, including diesel and alternate fuel modeling. Gasoline and alcohol can be modeled at standard and enriched air/fuel ratios for detonation control and you can also simulate with propane gas, propane LPG, or CNG (methane) fuels. The software adjusts spark for best power and predicts knock and retard timing to prevent detonation. This version incorporates 20 additional inputs including the ability to check valve-to-piston clearance and full cylinder head flow data. You can input flow volumes with up to 8 valve-lift increments. Each of the 23 outputs calculated for each RPM can also be graphed with 7 overlays. And you can substitute new engine mods right in the graph screen and immediately see changes to the power curve.
Engine Analyzer Pro
This version incorporates intake and exhaust port pressures based on Finite Difference wave simulation. It specifies net flow over the entire valve event including net trapped fresh mass charge and heat transfer to all chamber components. Simulations take longer in this version because of the greater number of calculations requested of the processor. Precise information calculated includes piston position, valve opening and flow, cylinder pressure, instantaneous torque, and piston thrust in onetenth- degree increments up to 720 degrees to complete a full cycle. Successive cycles are repeated to obtain a constant result based on wave tuning that splits intake and exhaust runners into small sections to precisely calculate pressure, velocity, momentum, friction losses, heat transfer, and other pertinent information that can require up to 60 seconds or more of calculation time, depending on the degree of accuracy you have specified.
The program auto-selects best spark advance or you can input a forced spark curve with 6 break points that you can specify produces best power for the desired burn rate. It also calculates a knock index so you can model with trace detonation. While no program can fully predict conditions that may cause intermittent detonation in one or more cylinders, Engine Analyzer Pro delivers highly accurate predictions based on qualified assumptions.
This advanced version offers up to 50 outputs per RPM including some only applicable to special valvetrain dynamics or turbo/supercharger applications. With up to 42 special calculations, it includes cam specs at 0.200-inch tappet lift and lift at TDC. You can also specify metric inputs and outputs and graph 25 different types if you have cycle data including valve lift, piston thrust, port pressure, valve flow versus crank angle and cylinder volume (pressure/ volume diagrams). In this version you can overlay up to 12 different tests for comparison purposes.
The “Chain Calculation” feature lets you increment one to six engine mods through two to six selected settings that may require several hours to calculate depending on your processor. Upon completion you can pinpoint the best power output and identify the components and optimum tuning specs that produced them. Another unique feature is the ability to optimize for the Engine Masters Challenge requirements so you can predefine and model your proposed entry.
Engine Analyzer Pro is one of the most robust, affordable simulation programs available. All versions of the program create power curves that integrate into Performance Trends’ vehicle simulation programs such as Drag Race Analyzer, Circle Track Analyzer, or a fuel economy calculator. The best part is an auto-linking component that automatically provides an ET, 60-foot time, MPH, lap time, and miles per gallon right in the Engine Analyzer program for instant verification of results. When visiting www.performancetrends.com, also check out the Rotating Inertia Calculator, which helps you predict the effects of an engine’s rotating components on the overall “effective weight” of the vehicle.
Racing Systems Analysis
Racing Systems Analysis (www.quarterjr.com) offers a junior and a pro version of its engine simulator. Racing Systems Analysis (RSA) is best known for its Quarter Jr. drag racing analysis program that has been serving the drag racing community for more than 20 years. Quarter Jr. and Quarter Pro are two of the most popular drag racing simulators available for race modeling especially for those two have accurate dyno data on their engine combination. Engine Jr. and Engine Pro build on that solid reputation.
Engine Jr. Engine Jr. is based on extensive collation of existing dyno test data matched with known engineering theory and fundamentals. It requires input of basic information including bore, stroke, rod length, compression ratio, cam specs, manifold type, valve specs, carb specs, carb type, and fuel. In return it provides peak horsepower, torque, power per cubic inch, and recommended redline and shift points. It also calculates minimum port cross-sectional area, mean flow velocity, and CFM per square inch of cross section. Four auxiliary worksheets help you calculate compression ratio and estimate carb and throttle body flow, cylinder head flow, and minimum cross section at the intake valve throat. In addition to performance results it also provides a graphic dyno curve with tabular horsepower and torque in 100-rpm increments. It’s a very powerful program for entry-level enthusiasts who want to model performance engine combinations.
Engine Pro takes it to the next level with an intake port flow worksheet that accommodates bench data input. It helps you model intake and exhaust systems and allows you to examine intake ramming and wave tuning occurring in both tracts. It models port data and makes recommendations on valve size based on your inputs. It also provides extensive mechanical details regarding piston speed versus RPM and piston position versus crank angle. The intake flow detail screen uses your input data to determine piston flow demand relative to valve timing. You can also infer tips on how to obtain greater accuracy from your flow bench testing by using a higher test pressure than the standard 28 inches of water.
Once you have modeled your best engine combination, you can import test results to RSA’s other performance software for drag racing and speed trails. These programs use your modeled data to predict track performance and they also accept actual dyno data if you have it. RSA also has an air density program (see Chapter 10) that helps with final tuning at the track.
Comp Cams/ProRacing Sim
Comp Cams is the parent company of ProRacing Sim. It’s software is available via both of their Web sites: www.compcams.com and www.proracingsim.com.
DeskTop Dyno 5 This engine simulation software delivers extensive component testing at a high level of accuracy. It can model 4-cycle engines with up to 12 cylinders and displays horsepower, torque, VE, and other results on customizable fullcolor graphs and tables. ProRacing Sim claims accuracy to within 5 percent of actual dyno results. Extensive menus provide instant access to specs on thousands of engine components or you can input your own custom specs. The program features powerful auxiliary calculators for detailed analysis including an airflow pressure-drop calculator, induction flow calculator, and cam math calculator. Like most simulation programs, you can simply input your specs or select stored specs and watch the results materialize in seconds.
The “Quick Iterator” function provides automated testing that seeks optimum component combinations for any application. This handy tool selects components, performs virtual dyno tests, and pinpoints the ideal combinations. You can test engine speeds from 1,000 to 14,500 rpm and get results with scalable graphs of power, toque, and pressure curves. Then retest with alternate fuels or nitrous oxide if you wish. Test at any desired air/fuel ratio with carbs or injectors and any manifold type. The simulator models multiple valves and permits full manipulation of cam timing events. It also includes flow data models and cylinder heads with input specs. The builtin component library contains specs for almost every domestic and foreign engine including thousands of predefined short-block assemblies. It also comes with a 160-page full-color manual which you can download for free and study before you buy.
DynoSim5 Like DeskTop Dyno 5, DynoSim5 performs full-cycle simulations using the standard Filling and Emptying model. DynoSim5 delivers even more sophisticated simulations that include environmental effects, combustion and chamber shape modeling, ignition timing with advance curve graphing, new forced-induction modeling, a rocker ratio and lash calculator, and data files exportable to Microsoft Excel for further analysis. The program contains even more choices for multi-valve cylinder heads and it allows selection and evaluation of specific combustion chamber configurations.
Another unique feature native to DynoSim5 is the built-in compression math calculator that features two modes: a known volume mode and a burette measured mode. Either mode accepts user input of known or measured values and the burette measured mode provides alternate input windows to accept burette measurements taken with the piston-down-the-bore method described in Chapter 3. The combustion chamber selector provides nine different combustion geometries based on chamber shape, burn rate characteristics and chamber timing requirements based on gasoline. DynoSim5 also incorporates an advanced ignition cycle model optimized for minimum advance best torque (MBT).
The amount of component selection and modeling in DynoSim5 is truly extraordinary. Be prepared to spend many hours simulating combinations while gaining a deeper insight into the dynamics of performance engines.
Motion Software is the originator of the DeskTop Dyno program. www.motionsoftware.com
Dynomation-5 Pro is the so-called Cadillac simulator based on extensive wave action simulation. It puts the user directly inside a running engine combination to view, analyze, and understand the powerful wave dynamics that influence induction and exhaust flow. It provides evaluation of specific intake runner lengths, section widths, port taper angles, header tubing and collector dimensions, and how they affect VE and the operational gas dynamics in the engine. Variations in pressure and flow velocities at the valve/chamber interface are displayed along with induction and exhaust pressure pulses and mass flow data.
The visual representation of these complex dynamics provides surprising insight into how torque and horsepower are manufactured inside a turning engine. A 3-D cutaway engine model shows mass flow, port velocities, and pressures all synchronized to crank angle for pinpoint analysis of camshaft profiles. It accepts test data from Cam Pro, Cam Pro Plus, S96, and Cam Doctor files. The 3-D model shows piston motion, gas dynamic flow, and visual representation of mass flow intake pressure waves and velocities and more throughout the entire four-cycle combustion process.
The seamless combination of the Filling and Emptying model and the wave dynamics in Method of Characteristics accurately predicts the interaction of complex pressure wave and gas particle flow. This pinpoints optimum port sizes, shapes, and lengths for both intake and exhaust plus integrated cam timing and valve motion analysis. Additional output data includes indicated horsepower, friction horsepower, pumping horsepower, mechanical efficiency, gas force on the piston, induction airflow, and piston speed. Pressure waves are shown on the 3-D engine, along with keys to the accompanying crank angle.
Dynomation also models most types of fuels and all boosted and nitrous-oxide applications with appropriate inputs for tight control of simulation characteristics. Full exhaust system modeling is also incorporated, including mufflers, catalytic converter backpressure, and stepped headers plus collector size, length, and taper. If your engine runs variable valve timing, Dynomation can simulate it while providing full lobe acceleration modeling and analysis.
More than 6,000 real cam profiles are available for selection or you can input your own custom specs. Even professional engine builders do not underestimate the powerful insight that Dynomation provides.
Some of the most pertinent support programs include Racing Systems Analysis’ DENSITY altitude program, Quarter Jr., Quarter Pro drag racing simulators, and Bonneville Pro, which uses real or simulated engine output data to model top speed efforts at Bonneville and other high-speed venues. RSA also offers Engine Pro: The Book with a free audio cassette for an in-depth tour of its engine simulation software.
Performance Trends backs up its Engine Analyzer series with multiple programs, including a comprehensive compression ratio calculator and fuel injector calculator that calculates injector size, pulse width and duty cycle, pressure corrections, EFI controllers, and other calculations unique to electronic fuel injection applications. They also offer Port Flow Analyzer for flow bench analysis and the Cam Analyzer for measuring and evaluating cam profiles.
And, finally, for the very hardcore among us, I recommend a visit to www.hi-techniques.com to check out the advanced engine analysis and data acquisitions components. While not for the home PC, its systems allow engine dyno operators to data log real-time cylinder pressure traces plotted against individual cylinder torque and horsepower output (see Chapter 5). This is the type of support that helps designers pinpoint deficiencies in various cylinders and redefine component relationships to bring individual cylinder power production in line with all contributing cylinders.
Written by John Baechtel and Posted with Permission of CarTechBooks