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 Last Update: 14 Aug 2017

- Modern Aircooled 4-Cylinder Aircraft Engine
Using Contemporary Engine Technology -

126 HP, 186-pound, O-200 Replacement

NOTE: All our Products, Designs and Services are ORGANIC, GLUTEN-FREE, CONTAIN NO GMO's, and will not upset anyone's precious FEELINGS or delicate SENSIBILITIES.

In early 2013, the CEO of a well-known aircraft component company contacted EPI to inquire about the feasibility of designing and developing a clean-sheet aircooled engine to replace the ancient, expensive and underpowered Continental O-200.

Those discussions resulted in the commencement of an intensive engine design program at EPI, with consultation and review input from the chief engineer at a well-known and respected supplier of PMA engine parts for Continental and Lycoming engines.

The engine that resulted from this program is a 200 cubic inch, horizontally-opposed 4-cylinder engine which is a bolt-in replacement for the O-200, and which (as of current dynamometer testing) produces 126 HP at 2700 RPM, corrected to accepted sea-level, standard conditions (59°F ambient temperature and 29.92 in-hg ambient pressure). The prototype engines weigh 191 pounds, but there is a weight-loss program underway which looks as if it will reduce the weight by an additional 5 pounds with no effect on reliability or power output.

Although the power output of this new engine is 26% greater than the ADVERTISED 100 HP of the O-200, our engine, in reality, produces over 32% more power than the O-200. We say that because, of the several brand-new O-200-D engines (advertised at "100 HP" ) that we have tested on the same dyno facility, NONE has ever exceeded 95 HP (corrected to the same 59°F, 29.92" standard).

Please note that this apparent discrepancy is NOT due to any inherent misrepresentation on the part of the certified engine manufacturer. Instead, the discrepancy arises from a biased correction procedure which the FAA allows to be used on all reciprocating engines certificated under FAR-Part-33. If the dyno-tests for this new EPI engine were corrected to the accepted FAA standards for certified engines, the result would be 134 HP. (We prefer to advertise actual, standardized power measurements.).

The following picture shows one of the prototype engines being built up for a testing session.

Prototype Engine Build-Up

Prototype Engine Build-Up

This engine embodies innovative technology and features which provide high output, low fuel consumption, and extremely reliable operation in aircraft service. These features include:

  1. High strength-and-stiffness crankcase cast from a premium heat-treated alloy;
  2. Optimized multi-gallery lubrication system with full-flow spin-on filter, oil cooler ports, and integrated oil thermostst;
  3. Custom-designed high-strength, high-stiffness crankshaft that has an integrated 4-inch propeller extension, allowing better cowling aerodynamics;
  4. High-strength H-beam connecting rods;
  5. Pistons forged from a high-strength aluminum alloy (which was developed by Rolls-Royce for aircraft engines) and tailored specifically for the air-cooled cylinders on this engine;
  6. High-pressure oil jets to cool the underside of the pistons;
  7. Alloy-steel camshaft with custom-designed lobes, tailored to produce high opening and initial closing velocity (for more area under the lift curve) together with low seating velocity (for prolonged valve and seat life), and which have extremely smooth first, second and third derivative profiles;
  8. Hydraulic roller cam followers;
  9. High-strength progressive "beehive" valvesprings which dramatically reduce sensitivity to vibration excitations from higher harmonics of the lift and acceleration profiles;
  10. Stiff pushrods;
  11. Very strong and stiff rocker arms on needle-bearing trunnions;
  12. Intake and exhaust valves made from very-high-temperature and very-high-strength alloys;
  13. High-flow intake and exhaust ports;
  14. Combustion chambers with high-squish and rapid flame-front propagation properties;
  15. All sealing between static components done with O-rings;
  16. High-grade fasteners throughout;
  17. Unusually-high heat-rejection capabilities engineered into the cylinders and heads;
  18. Contemporary electronically-controlled fuel injection and ignition, with optimized maps;
  19. A custom-designed redundant ECU which will be certified to existing standards;
  20. .......and MORE.

Many of the internal components are purchased from manufacturers that (a) have track-records of producing engine parts and subsystems that survive brutal testing scenarios and (b) that have robust and proven QC systems in place.

Unfortunately, the vendor initially selected for machining the crankcase and cylinder castings (which, BTW, came highly recommended and alleged to be producing components for certified engines) proved to be incapable of demonstrating the remotest comprehension of basic machining skills and quality standards {never mind aircraft quality standards}. That (very expensive) experience convinced the client to move as much of the critical manufacturing processes as is practical to in-house facilities in order to assure the highest quality standards.

The following pictures show a few of the internal components.

Crankcase Half

Finished Crankcase Half (Port Side)

Camshaft in Measurement System

Prototype Camshaft Being Measured for Lift, Velocity, Acceleration and Jerk Profiles

Piston and Connecting Rod

Piston, Pin and Connecting Rod

Finish-Machined Cylinder

Finish-Machined Cylinder

This engine was completely designed in 3D-CAD (SolidWorks). We subjected all critical components to extensive FEA in order to maximize reliability and to provide sufficient strength margins for future developments, including a 160+ HP turbocharged version with a constant-speed hydraulic propeller.

The following pictures show a tiny sample of the many FEA studies done on the crankshaft, pistons, rods and wristpins. The first picture shows one of the many cases run on the crankshaft. In this case, we applied combined overloads from all major sources (117% of peak combustion pressure, 125% of peak inertial loads, 125% of maximum possible propeller thrust, and the gyroscopic load generated by a propeller with 125% of the mass moment of inertia of the service propeller turning at 2700 RPM under the influence of a 2.5 radian-per-second pitch (or yaw) rate. In this case, the max stress was a modest 56 ksi, located (as expected) in the rod journal fillet radii.

Crankshaft FEA

Crankshaft at 12° ATC with 1400 PSI Combustion Pressure,
Plus 125% Max Inertial, Gyroscopic and Thrust Loads

Piston, Pin and Rod with asymmetric combustion pressure

Piston, Pin and Rod with Asymmetrically-Applied Peak Combustion Pressure

The first run of the first prototype engine occurred on 23 November 2016, and was very successful. After careful break-in and thorough in-process evaluations (spanning several weeks), the engine was finally subjected to an extended run at full power. During that run, it produced 126 corrected HP at 2700 RPM using fuel and spark maps that had not yet been optimized. Further increases in peak HP are expected as development continues.

Watch a short movie of the first run of the engine and the first full power test HERE.

As with any completely new engine, we have experienced some minor problems. Those are being addressed in preparation for an extended full-power dyno-testing program, followed by in-flight testing as soon as the targeted reliability has been confirmed by ground-testing and teardown inspections.

The great news about this engine is that the targeted sales price is less than half that of a Continental O-200-D.

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