From: EPI Inc.       Contact: tech@epi-eng.com

 

  Race Engine Technology Magazine

Race Engine Technology
The Premier Engine Magazine

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- Piston Engine Technology -

Articles Describing Technical Aspects of Engine Design and Operation

In early 1993, EPI began the development of a lightweight, 500 HP, liquid-cooled V8 aircraft powerplant for a high-performance, two-place tandem aircraft which EPI's CEO had designed.

Several products have resulted from that development program, including PSRU's, ignition systems, lubrication systems, accessory drives, and engine mounts.

The design and development of the EPI Gen-1 powerplant (engine, PSRU, and accessory drives) was the subject of a technical presentation which EPI's CEO gave at the 1996 Advanced Engine  Technology Conference (AETC). This section of the website expands on that presentation in order to make the basics of engine design, development and evaluation available to a wider audience.

In December, 2006, EPI's CEO gave another AETC presentation covering various loads and stresses imposed on reciprocating engine components. (The content of the 2006 AETC presentation are being added to this section as time allows.)

If you are considering the use of a non-certified engine for an aircraft you are designing or building, we strongly recommend that, in order to be as well informed as possible in the selection of an engine for your aircraft, you read and digest the information presented in the AIRCRAFT ENGINE CONVERSIONS section of this site.

Quoting from the INTRODUCTION page of that section:

"It is our opinion, based on real-life data, analysis and experience, that for engines up to about 325 HP, the best way to satisfy the requirements of (1) reliability, (2) power-per-pound, (3) ease of installation, (4) availability, and (5) support, is to use an appropriate certified engine (Lycoming, Continental, etc.)."

If you have decided to use a liquid-cooled V8, the next choice is whether to build it yourself or to buy it from one of the many current sellers of alternative powerplants.

Whatever the result of that decision, you need certain tools to evaluate either (a) the validity of your design decisions or (b) the validity of the (sometimes outrageous) claims of engine vendors. The Engine Technology information presented here is intended to provide information to assist in those evaluations.

The details about the EPI Gen-1 engine, as well as the EPI Gen-2 aircraft powerplant and a new engine EPI is developing, can be seen in the Aircraft Engine Products section.

Table of Contents

 1. Horsepower and Torque

ABSTRACT:
This document explains the difference between power and torque, and explains how power depends on torque and RPM.
IT IS ESSENTIAL THAT YOU UNDERSTAND THIS SUBJECT.

 2. Converting Fuel into Horsepower

ABSTRACT:
This document explains how engines convert fuel energy into mechanical energy, and the inherent limitations of that conversion, along with a yardstick to evaluate the claims of engine builders.

 3. The Importance of Volumetric Efficiency

ABSTRACT:
This document presents the concepts defining the efficiency of an engine's air-pumping capability, and how mass airflow is the critical determinant of engine performance.

 4. Brake Mean Effective Pressure (BMEP)

ABSTRACT:
This document explains one of the fundamental yardsticks of engine performance, and how to use it in evaluating the reasonableness of horsepower claims.

 5. Piston Motion

ABSTRACT:
This document explains the unusual way that a piston moves in its cylinder, and provides the basis for understanding subsequent subjects.

 6. Piston Velocity and Acceleration

ABSTRACT:
This document explains the critical yardsticks of piston velocity and acceleration, with primary and secondary components.

 7. Forces on Reciprocating Components      (PAGE UNDER CONSTRUCTION)

ABSTRACT:
This document explains the forces that are generated within an engine during key portions of the intake-compression-combustion-exhaust cycles.

 8. Camshaft and Valvetrain Fundamentals

ABSTRACT:
This document presents the basics of valve operation, describing cams and the associated valve-moving componentry.

 9. Valvetrain Velocity and Acceleration      (PAGE UNDER CONSTRUCTION)

ABSTRACT:
This document describes the phenomenal forces, accelerations and vibrations which are common in today's high performance engines.

10. Port Flow and Combustion Chambers      (PAGE UNDER CONSTRUCTION)

ABSTRACT:
This document describes the basics of achieving and verifying high levels of flow while maintaining high flow quality.

11. Bearings and Lubrication Systems         (PAGE UNDER CONSTRUCTION)

ABSTRACT:
( Page Still Under Construction ) This document explains engine lubrication systems and requirements, with a discussion of oil pumps and pump hype.

12. Cooling and Heat Rejection                  (PAGE UNDER CONSTRUCTION)

ABSTRACT:
This document explains the cooling problems faced by a high-power engine operating continuously at a high percentage of max output.

13. The Torsional Output of Piston Engines

ABSTRACT:
This document describes the origins and severity of the torque spikes which occur every time a cylinder fires.

14. Crankshaft Torsional Absorbers

ABSTRACT:
This document explains the purpose and operation of the torsional absorbers (misnamed "dampers") on the free end of an engine crankshaft.

15. Reversing the Rotation of an Engine

ABSTRACT:
This document explains the issues which need to be addressed when the direction of crankshaft rotation of an engine is changed.

16. Comparison of the Ultimate V8 Engines

ABSTRACT:
This document compares the world's Definitive V8 engines (NASCAR Cup and Formula-One) using several important criteria. It is an expanded version of an article which originally appeared in issue 029 of Race Engine Technology magazine.
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