RED Image

Four Stroke Simulation Introduction

The following is an outstanding summary of the four stroke simulation process.  It is quoted directly from the introductory page of the Dynomation Handbook.

          "What makes this program unique?"

          "It probably requires little effort to convince the engine builder of the benefits of engine simulation. The sheer number of variables which have an influence on the internal combustion engine make the development process a long and costly procedure. This truth is nowhere greater than in the research and development stage for engine manufacturers. Considerable capital is expended on design, prototype models, and testing before the manufacturer can release its engine to the general public. A technique which would help engineers and researchers analyze various engine designs without the expense and time of producing one off prototypes would be an invaluable asset. This "asset" is the computer simulation and its use in industry has been a mainstay for over 30 years."

          "There has always been (and always will be) an effort by engine researchers to develop computer models which will more accurately represent the true physical process occurring within the internal combustion engine. For many years now sufficient knowledge of the thermodynamic and fluid mechanic process has been known to develop simulation models which are sufficiently accurate to help with design optimization. Needless to say, these models vary in their complexity and ability to incorporate critical phenomena."

          "In general there are three types of engine simulation models that incorporate varying levels of completeness. Moving from the least to most complete are Quasi-Steady Flow models, Filling and Emptying models, and Wave Action models."

          "Quasi-Steady models are relatively simple models that rely heavily on empirical data to determine restriction values for interconnected components such as air cleaners, throttle, port, and valve systems. This method is easily recognized by the fact that it cannot predict power levels at various engine speeds. It can only predict maximum power potential. It also completely ignores the important wave tuning effects created by intake and exhaust ducting dimensions and cannot calculate the inertia ram effect of the gas particles which occurs before the intake valve closes."

          "Filling and Emptying models are next in the line of sophistication. These models use the finite volume of the manifold sections and then calculate the mass flow rates across these sections. Filling and Emptying models are capable of predicting power levels across differing engine speeds. However, like the Quasi-Steady models they also ignore the wave tuning phenomena and cannot calucate the inertia ram effect of the gas particles which occurs before the intake valve closes."

          "For may years researchers as well as engine builders have known of the significant influence of "tuning effects" created by intake and exhaust ducting dimensions. The Wave Action models were developed to take these effects into account. The pioneering work in this field was conducted in Great Britain during the early 1940's. By the middle of the 1950's a mathematical technique was developed which would describe the wave motion phenomena. This technique was known as the "method of characteristics". Unfortunately, the arithmetic involved was nothing short of horrendous and this added little help for the design engineer of the day. Fortunately, in 1964 a breakthrough occurred when researcher Roland Benson develped a solution of the method of characteristics using a digital computer. Now it was possible to let the computer "grind" through the tedious mathematics, thus giving engineers a practical method for analyzing the effects of wave dynamics."

          "Wave Action simulators are the most sophisticated of the simulation models available for analysis of the gas exchange process. They are extensively used in industry for engine research and development and should likewise be of extreme value to the high performance engine builder. In fact, wave tuning effects play such an important role in the high performance engine that the Wave Action simulation technique is the only logical choice for development of these engines. The Dynomation program was developed just for this purpose. It is a true Wave Action simulation program which will allow the "high tech" engine builder to conduct research and development at a new level."

          "Only recently has the personal computer developed adequate processing power to solve the complex wave action calculations in a reasonable time. The use of a math co-processor is a requirement and a 486 or Pentium chip is highly recommended. A 486-50 MHz machine using a math co-processor can usually conduct a complete powerband sweep simulation in about 6 minutes. If there is a downside to the Wave Action simulation, it is the required processing time. However, with the computer industry's trend toward more and more processing power this will cease to be a problem shortly. Meanwhile, the high level of information provided by Wave Action simulation certainly outweighs the required waiting times."

          My labor rate is $60 per hour.  I charge just for data input/analysis time... the computer running time is without charge.  This is significant since each simulation requires typically 6 to 40 minutes of dedicated running computer time (or more) to accomplish.  If that seems like a long time, consider how long it might take to separately build and test each individual proposed set-up change...  I can generally get you accurate results in one to three hours of actual data input/analysis time... sometimes less.  It all depends on how far you care to look into a given project.  Most folks give me a dollar limit not to be exceeded without further approval and a communication of results overview to that point.

           Methods of payment are business or bank check.  Sorry, I do not accept personal checks or credit cards.  You may freely submit your information using the form that follows.  I will then contact you by e-mail or phone and clarify any needed details while also establishing a spending limit.  You will be required to pay me before any written data summaries or graphs of the simulations can be forwarded to you.  Payment can be sent to the address at the top of the Homepage.  Please submit any other questions by e-mail here.

          Please proceed by clicking here.


Auto Harley Vintage Jap Bike Two Stroke Int-Exh Syst Outboard History Ref's Links Search Home