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  Last Update: 15 May, 2023

- Aircraft Engine Conversions -

Design Considerations and EPI Conversions

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EPI, Inc. has worked on several engine conversion programs, including programs to develop STC'd retrofit packages to install the Orenda™ certified 600 HP liquid-cooled powerplant into the Aero-Commander 685 and the Air Tractor 401 aircraft.

One very interesting conversion project (2011) was the development of the V8-powered, EPI-Mark-9-Gearbox equipped Periera GP-5 Reno Racer, which competed successfully in the 2012 Reno Air Races. Others include the development of a firewall-forward 600-HP liquid-cooled powerplant system to retrofit onto existing airframes which are currently using the ancient P&W R-1340 radial engine. This powerplant is designed to run on 92-octane pump gas and to perform like a turbine-powered aircraft at less than half the hourly cost of a turbine.

The knowledge gathered during several engine conversion projects, both experimental and for STC, together with general design considerations which apply to any aircraft engine conversion program, are presented in the following sub-sections.

Table of Contents

 1. Introduction and Background The concepts and issues which must be considered when planning to convert an aircraft from an existing engine to a different one, and when selecting an engine for an experimental aircraft.

 2. The Primary Consideration in a Conversion The most-frequently misunderstood consideration with regard to planning an engine conversion.

 3. Evaluating The Wisdom of an Engine Conversion A few more harsh realities to be considered regarding aircraft engine conversions, with a handy comparison table at the end.

 4. Other Important Engine Conversion Criteria Several other important considerations involved in an engine conversion, including CG considerations, engine mount structure, cooling capacity, turbochargers, etc.

 5. Engine Conversions on Certified Aircraft    "Can you help me put a V8 in my Bonanza / 210 / 421 / whatever ?"    This article presents the issues surrounding this type of inquiry. If you are considering such a project, please read here first and consider the realities.

 6. Whirl Mode Issues An introduction to WHIRL MODE: an important issue in engine mount design which is often-ignored but extremely important to your health.

 7. Engine Mount Structure Design EPI's methodology and standards for designing and producing an engine mount structure.

 8. Custom Mount for Spacewalker-2 Detailed description of the design and analysis of a custom mount to solve a severe aft-CG problem.

 9. GP-5 Reno Racer Powerplant upgrade program for the Periera GP-5 Race Plane and its success at the 2012 Reno Air Races.

10. The 21st Century Cropduster The replacement of an aging R-1340 on an Air Tractor-301 with a modern, efficient, and inexpensive engine package.

11. Orenda V8 onto an Air Tractor 401 The replacement of an aging R1340 on an Air Tractor-401 with a heavy, expensive engine package.

12. Orenda V8 Engines on an Aero-Commander 685 An engine conversion which produced a high-performance but unfortunately full-fuel, zero-person aircraft.