:. Projects
:. Asteroseismology
:. Dark Matter Galaxies
:. EPR
:. Gravitophotons
:. Hybrid Rocket Engine
:. Pulse-Ram Induction

:. Sections:
:. Introduction
:. Purpose
:. Problem
:. Test
:. Theory
:. Analysis
:. Design Parameters
:. Concepts
:. Final Design
:. Evaluation
:. Conclusion
:. Appendix A
:. Appendix B
:. Appendix C
:. Appendix D

:. Data:
:. Torque Power Data
:. Compression Data

:. Feedback:
:. thegraben@gmail.com

:. Sponsors
:. The Graben

Importance of Intake Optimization:

As mentioned earlier, engine performance depends on the delivery of an adequate amount of air/fuel mixture for combustion. In theory, by increasing the mass of trapped charge at the time of ignition, one can obtain a proportional increase in output. The upper limit of this effect is dictated by the mechanical robustness of the engine and by the detonation limit of the air/fuel mix.

Volumetric efficiency (VE) is defined as the mass of charge trapped in the cylinder on each compression stroke divided by the mass of charge that would fill the cylinder if it were open to the undisturbed atmosphere at steady state. In simplest terms, VE is directly proportional to output torque. Since power is defined as torque times the engine speed (in radians per second), VE is also proportional to power output. Due to the inertial effects of the air in the induction tract, VE tends to decrease with increasing engine speed. Thus, when the highest output is demanded of the engine (at high engine speeds), the engine is the least capable of producing it. Proper design of the induction system can attenuate this detrimental effect and even allows the designer to create a custom powerband tailored to the particular engine’s use.

   
   
   
   

There are many ways to improve VE. Some high-performance engines make use of forced-induction devices such as exhaust or crank driven compressors. While very effective, such devices must balance benefit against the additional load placed on the engine, back work in the case of a supercharger or exhaust backpressure in the case of a turbocharger. In addition, a high level of artificial supercharge can raise the temperature of the air/fuel mixture high enough to cause spontaneous combustion or detonation, which causes engine damage and loss of performance. A more subtle approach to improving VE is optimization of the intake system. By reducing restriction and using the engine’s own intake pressure phenomena, VE can be increased significantly. Also, since in such a naturally-aspirated engine there exists always a partial vacuum in the intake tract, pressure-heating of the mixture is rarely a problem. Optimization of the induction system to reduce restriction and make use of pressure-pulse phenomena was the approach used for this project.